THE EYE

The human eye is the organ which gives us the sense of sight, allowing us to learn more about the surrounding world than we do with any of the other four senses.  We use our eyes in almost every activity we perform, whether reading, working, watching television, writing a letter, driving a car, and in countless other ways.  Most people probably would agree that sight is the sense they value more than all the rest.

The eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world by processing the light they reflect or emit.  The eye is able to see in bright light or in dim light, but it cannot see objects when light is absent.

process of vision

Light waves from an object (such as a tree) enter the eye first through the cornea, which is the clear dome at the front of the eye.  The light then progresses through the pupil, the circular opening in the center of the colored iris.  Next, the light passes through the crystalline lens, which is located immediately behind the iris and the pupil.

Initially, the light waves are bent or converged first by the cornea, and then further by the crystalline lens, to a nodal point (N) located immediately behind the back surface of the lens.  At that point, the image becomes reversed (turned backwards) and inverted (turned upside-down).

The light continues through the vitreous humor, the clear gel that makes up about 80% of the eye’s volume, and then, ideally, back to a clear focus on the retina behind the vitreous.  The small central area of the retina is the macula, which provides the best vision of any location in the retina.  If the eye is considered to be a type of camera, the retina is equivalent to the film inside of the camera, registering the tiny photons of light which interact with it.

Within the layers of the retina, light impulses are changed into electrical signals and then sent through the optic nerve, along the visual pathway, to the occipital cortex at the posterior or back of the brain.  Here, the electrical signals are interpreted or “seen” by the brain as a visual image.  When the light entering the eyes is bright enough, the pupils will constrict (get smaller), due to the pupillary light response.

Actually, then, we do not “see” with our eyes but, rather, with our brains.  Our eyes merely are the beginnings of the visual process.

eye growth

The average newborn’s eyeball is about 18 millimeters in diameter, from front to back (axial length); it grows slightly to a length of approximately 19½

millimeters as an infant; and it continues to grow gradually to a length of about 24-25 millimeters, or about 1 inch, in adulthood.  (A ping-pong ball is about 1½ inch in diameter, which makes the average adult eyeball about 2/3 the size of a ping-pong ball.)  The eyeball is set in a protective cone-shaped cavity in the skull called the “orbit” or “socket.”

extraocular muscles

The orbit is surrounded by layers of soft, fatty tissue which protect the eye and enable it to turn easily.  Three pairs of extraocular muscles regulate the motion of each eye: the medial/lateral rectus muscles, the superior/inferior rectus muscles, and the superior/inferior oblique muscles.

eye structures

Among the most important components of the human eye are the cornea, conjunctiva, iris, crystalline lens, vitreous humor, retina, macula, optic nerve, and extraocular muscles.  Click on the names of each of these 9 ocular structures on the left (either in the upper picture or in the lower frame of links) to learn more about them.  Then take the three short quizzes at the end, if you wish.

Eye Anatomy

A guide to the many parts of the human eye and how they function.

The ability to see is dependent on the actions of several structures in and around the eyeball.  The graphic below lists many of the essential components of the eye's optical system.

                   

When you look at an object, light rays are reflected from the object to the cornea, which is where the miracle begins.  The light rays are bent, refracted and focused by the cornea, lens, and vitreous. The lens' job is to make sure the rays come to a sharp focus on the retina. The resulting image on the retina is upside-down.   Here at the retina, the light rays are converted to electrical impulses which are then transmitted through the optic nerve, to the brain, where the image is translated and perceived in an upright position!

Illustration by Mark Erickson

Think of the eye as a camera.  A camera needs a lens and a film to produce an image.  In the same way, the eyeball needs a lens (cornea, crystalline lens, vitreous) to refract, or focus the light and a film (retina) on which to focus the rays.  If any one or more of these components is not functioning correctly, the result is a poor picture.  The retina represents the film in our camera.  It captures the image and sends it to the brain to be developed. The macula is the highly sensitive area of the retina.  The macula is responsible for our critical focusing vision.  It is the part of the retina most used.  We use our macula to read or to stare intently at an object.

Buzzwords for eye anatomyorbit: This cone shaped cavity in the skull is formed by the frontal, maxilla, zygomatic, sphenoid, ethmoid, lacrimal and palatine bones. These bones are thin and are often subject to fractures. The eye occupies the front portion on the cavity with the rest being filled with fat, nerves, blood vessels, muscle and the lacrimal (tear) gland.

anterior chamber: This front chamber of the three found in the eyeball itself is found between the cornea and the iris.

posterior chamber: This chamber occupies space between the iris and the lens.

aqueous humor: This fluid fills the anterior and posterior chambers. It is made by cells of the ciliary body and circulates from the posterior chamber, over the lens, to the anterior chamber and exits via the Canal of Schlemm. It

is similar to plasma but contains very little protein.

vitreous space: This chamber occupies the space behind the lens to the retina. It is filled with a gelatinous substance called the vitreous body.

sclera: This a fibrous protective covering of the eyeball that is seen as the white of the eye. It is made mostly of the structural protein collagen.

cornea: Transparent, colorless anterior one sixth of the covering of the eyeball. The cornea consists of 5 layers with the outer one being a layer of epithelium composed of 5-6 layers of cells that turnover every 7 days or so. This layer and the internal endothelium are responsible for keeping the cornea transparent. They do this by keeping the middle layers relatively dehydrated which keeps the parallel collagen fibers present there from being opaque. The cornea contains no blood vessels and gets its nutrients from those in the anterior chamber fluid and surrounding vessels.

Schlemm's canal: This canal drains fluid from the anterior chamber. Obstruction of this canal leads to an increased intraocular pressure which can damage the retina. This condition is also called glaucoma.

choroid: This is the vascular layer of the eye.

retinal pigment epithelium: This layer lying betwen the retina and choroid, contains melanocytes that make for its characteristic black color. This pigment allows the inside of the eye to absorb stray rays of light like the black paint inside a camera or within a dark room.

ciliary body: This is an expansion of the choroid at the front of the eye at the level of the lens. The lens is attached to the ciliary body which has smooth muscle within it. Contraction of this smooth muscle changes the shape of the lens and allows the eye to focus on objects. Part of the ciliary body is specialized to make aqueous humor.

iris: Another expansion of the choroid that partially covers the lens formed by pigment cells, fibroblasts, blood vessels, contractile pigment cells. The pigment found in the iris prevents light from entering the eye except through the pupil. The melanocytes (pigmented cells) are responsible for the color of the eyes. If there is little pigment in the cells the light reflected from the choroid at the back of the eye will make the iris appear blue. As the amount of pigment increases the iris appears greenish-blue, gray or brown.

pupil: Round opening in the iris that allows light to pass through. Pupil size changes based on the amount of light present. More light causes the pupil to contract while the pupil widens in the dark to collect as much light as possible.

lens: This biconvex structure is very elastic, at least in the young. With age the lens looses its elasticity and therefore the ability to focus on near objects decreases. The center of the lens is formed by elongated cells (fibers) that have lost all organelles and are filled with special proteins called crystallins.

These fibers are replaced throughout life but the regeneration slows down with age. Mature cataracts occur when these fibers accumulate pigment granules so that they are less transparent.

retina: The photosensitive part of the eye lies between the vitreous body and the choroid layer at the back of the eyeball and is a complex network of photosensitive cells and various types of neurons. Light that reaches the retina must travel through several layers of transparent neurons at the front of the retina before reaching the photosensitive rods and cones. The photosensitive part of rods and cones is housed in extensions of the cells that look just like their names. The rods are responsible for black and white vision while the cones detect color. The neurons within the retina act to integrate the visual signals received by the rods and cones and transfer the information to the optic nerve.

fovea: This specialized area of the retina is for the most acute vision. When a person is actively focusing or attending to an object the eyes are moved so that the image is focused on the fovea. It is thinner, containing only the cones necessary for detection of sharp images. The cones in this area are long and thin resembling rods so that they can be closely packed. Blood vessels are absent as well. Each foveal cone is directly connected to a neuron in the optic nerve.

blind spot: There are no photosensitive cells in this area of the retina. This is where the optic nerve and blood vessels enter the eye through the optic disc.

Physiology of Vision

The eyes convert light energy in the wavelengths of 397 to 723 nanometers into electrical signals in the optic nerve. Images of objects are focused on the retina where the photosensitive cells convert the light energy to action potentials. Rods contain the protein rhodopsin which contains a derivative of Vitamin A. Light bleaches the visual pigments which causes photochemical reactions to occur that amplify the signal. This information is transferred to the associated neurons which integrate the signals and transfer the information to the brain. A single rod is able to detect a single photon of light but the rods are low resolution detectors so that images are formed but without much detail. The human retina contains about 120 million rods. They very sensitive and are the receptors used when low levels of light are encountered. Peak sensitivity to light for rods is 505 nm which is roughly green light.

Color VisionIn the human, some 6 million cones are responsible for filling in the details and colors in a visual image. The cone photopigment is called iodopsin. There are three types of cones (red, green, and blue) based on their maximum sensitivity to the visible light spectrum which is determined by the particular variety of iodopsin produced by that cone. It is important to note that the sensation of any color can be derived from the proper mix of these three primary colors. Cones require a higher light intensity to illicit a response than the rods because they have a higher threshold for stimulation.

Dark AdaptationThe human eye can see things in quite a remarkable range of light intensity, bright sunshine to a moonless sky. This is due to dark adaptation, which is due to a change in the visual threshold. For instance, when a person comes inside to a movie theater from a bright sunny day their eyes gradually adapt to the darker environment. It takes about 20 minutes for full adaptation. The reverse process, adaptation from dark to light, takes about 5 minutes. Pilots, radiologists and others who need maximal visual sensitivity in the dark can avoid the 20 minute dark adaptation period if they wear red glasses or goggles in the light. Red lighting is used in photographic print development as well because the photographer can see acutely without ruining the print. This is because the rods are only minimally simulated by red light and they are chiefly involved in dark adaptation. The time required for dark adaptation is due to the time required to build up rhodopsin stores within the rods.

AccommodationThe lens in the eye is an elastic structure that changes shape in order to focus things near or far onto the retina. Optically, the greater the curvature of the lens, the greater its refractive power. To bring close objects into focus on the retina the lens must have a greater refractive power than in its resting state. This is accomplished via contraction of the ciliary muscles that hold the lens in place. When these muscle fibers contract, the lens, via its elasticity, springs into a more convex shape allowing a focused image of near objects. This is an energy requiring process since muscular effort is necessary, and therefore can be tiring.

Near PointThe nearest point to the eye that an object can be brought into clear focus is called the near point of vision. The near point gets farther away throughout life due to a loss of lens elasticity. For example, the near point at age 10 might be 9 cm and 83 cm at age 60. The loss of accommodation is often sufficient by age 40-45 to make close work and reading difficult. This can corrected by wearing glasses with convex lenses.

The eye manifests its refracting power via several curved surfaces, each separated by media with different indices of refraction. The most significant refractive surfaces are the anterior and posterior cornea and the anterior and posterior crystalline lens.

In the emmetropic eye (which has no refractive error), the range of corneal refracting power is between 39 and 48 diopters, while the range of lenticular refracting power is between 15 and 24 diopters.  In the emmetropic eye, the axial length (from the posterior corneal surface to the retina) varies from 22 to 26 millimeters, or approximately an inch.

The following are the clear ocular media and structures (through which light passes before it reaches the retina) and their respective indices of refraction:

• pre-corneal tear film• cornea• aqueous humor• crystalline lens• vitreous humor

   

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The Physical Structures of the Eye

Items refer to the human eye unless otherwise specified. This section leans heavily on Wyszecki and Stiles (1982) an excellent book.

Cornea Sclera Aqueous Humor Iris Pupil Lens Vitreous Humor Retina - gross anatomy

o The primary layers of the retina from outermost surface to innermost surface:

CARE OF THE CLIENTS WITH EYE DISORDERS

Diagnostic Assessment1) Snellen’s Chart

- tests visual acquity- normal result is 20/20- result of 20/20 indicates legal blindness

2) Ishihara Plate- test color vision

3) Retinoscopy- determines refractive error of an eye

4) Cover – Uncover test- differentiates various types of strabismus

5) Tonometry- indirect measure of IOP- normal is 11 – 21 mmHg

6) Gonioscopy- a biomicroscopic examination that visualizes the anterior chamber

angle- diagnoses congenital and secondary glaucoma

7) Perimetry- measurement of the peripheral vision field

8) Bjerrum Tangent Screen- measures central vision

9) Ophthalmoscopy- examines the fundus of the eye

10) Slit Lamp Biomicroscopy

- assesses the eye’s anterior portion under high magnification and in optical section.

- It can diagnose astigmatism

Vision Protection and General Eye Care- Regular ocular and physical examinations- Avoid dangerous items (toys, gums, arrows, fireworks, rocks,etc)- Early identification and treatment of strabismus in children- Routine eye assessment programs in school- Early treatment when eye symptoms occur- Routine instillation of appropriate drops in the eyes of every

newborn- Blood tests during pregnancy to identify syphilis- Inoculation against rubella- Regulation of oxygen concentrations administered to premature

infants- Avoid habitual rubbing of the eyes- Have adequate lighting when reading- Periodically rest eyes during prolonged periods of close work,

reading or watching television- Reduce glare and wear protected goggles- Keep eye glasses clean, protected from scratching and breakage

and properly aligned- Do not use eyewashes, eye drops, or any medications in the eyes

unless prescribed by a doctor- Never use a soiled wash cloth around eyes- Use care when using aerosol sprays- Maintain a state of good health and eat well – balanced diet with

adequate vitamins A, B and C.- Use care when using solvents, lye solutions, ammonia, caustic

solutions to avoid splashing or spilling into eyes

Common Ocular Medications- Local Anesthetics- Parasympathomimetic drugs – used as miotics

▪ Pilocarpine HCl 0.5 – 10% ▪ Carbachol 1.5 – 3% ▪ Acetylcholine Cl 1%

- Parasympatholytic drugs – used mydriatics ▪ Neo – Synephrine 2.5 / 10% ▪ Atrophine SO4 0.%, 1, 4% ▪ Scopolamine Hydrobromide 0.25% ▪ Cyclopentolate HCl (Cyclogyl) 1%, 2% ▪ Tropicamide (Mydraicyl) 0.5, 1%

- Antimicrobials ▪ Gentamycin 0.3% ▪ Neosporin ▪ Chloroptic eye drop

- Steroids- Carbonic anhydrase inhibitors – reduce aqueous humor production

▪ Diamox (Acetazolamide)

- Beta – Blockers – reduce aqueous humor production ▪ Timolol Maleate (Timoptic)

UVEITIS (Iritis)

DefinitionUveitis means "inflammation of the uvea", or the middle layer of the eye. The uvea consists of three structures: the iris, the ciliary body, and the choroid. The iris is the colored structure surrounding the pupil, visible in the front of the eye. The ciliary body is a structure containing muscle and is located behind the iris which focuses the lens. The choroid is a layer containing blood vessels that line the back of the eye and is located between the inner visually sensitive layer, called the retina, and the outer white eye wall, called the sclera. Inflammation occurring in any of these three structures is termed "uveitis".

Inflammation in uveitis may involve any but not necessarily all of these three structures. Depending upon which structures are inflamed, uveitis may be further subcategorized into one of three main diagnoses, these include:

iritis or anterior uveitis, iridocyclitis or intermediate uveitis, and choroiditis or posterior uveitis.

Uveitis may develop following eye trauma or surgery, in association with diseases which affect other organs in the body, or may be a condition isolated to the eye itself. Severe and permanent visual loss can result from uveitis. In addition, uveitis can lead to other ocular complications, which may produce vision loss, including glaucoma, cataracts, or retinal damage. Early detection and treatment is necessary to reduce the risk of permanent vision loss.

SymptomsDepending on which part of the eye is inflammed in uveitis different combinations of these symptoms may be present.

Redness Light sensitivity Floaters Blurry vision Pain

These symptoms may come on suddenly, and you may not experience any pain. The symptoms described above may not necessarily mean that you have uveitis. However, if you experience one or more of these symptoms, contact your eye doctor for a complete exam.

TreatmentTreatment may include steroid eyedrops, injections, or pills, as well as eyedrops to dilate the pupil and reduce pain. More severe cases of uveitis may even require treatment with chemotherapeutic agents to suppress the immune system.

CONJUNCTIVITIS (Pink Eye)

Overview

Conjunctivitis, commonly known as pink eye, is an infection of the conjunctiva (the outer-most layer of the eye that covers the sclera). The three most common types of conjunctivitis are: viral, allergic, and bacterial. Each requires different treatments. With the exception of the allergic type, conjunctivitis is typically contagious.   The viral type is often associated with an upper respiratory tract infection, cold, or sore throat. The allergic type occurs more frequently among those with allergic conditions. When related to allergies, the symptoms are often seasonal. Allergic conjunctivitis may also be caused by intolerance to substances such as cosmetics, perfume, or drugs. Bacterial conjunctivitis is often caused by bacteria such as staphylococcus and streptococcus. The severity of the infection depends on the type of bacteria involved. Signs and Symptoms   Viral conjunctivitis          Watery discharge          Irritation          Red eye          Infection usually begins with one eye, but may spread easily to the fellow eye   Allergic conjunctivitis          Usually affects both eyes          Itching          Tearing          Swollen eyelids   Bacterial conjunctivitis          Stringy discharge that may cause the lids to stick together, especially after sleeping          Swelling of the conjunctiva          Redness          Tearing          Irritation and/or a gritty feeling          Usually affects only one eye, but may spread easily to the fellow eye   Diagnosis   Conjunctivitis is diagnosed during a routine eye exam using a slit lamp microscope. In some cases, cultures are taken to determine the type of bacteria causing the infection.   Treatment  Conjunctivitis requires medical attention. The appropriate treatment depends on the cause of the problem.   For the allergic type, cool compresses and artificial tears sometimes relieve discomfort in mild cases. In more severe cases, non-steroidal anti-inflammatory

medications and antihistamines may be prescribed. Some patients with persistent allergic conjunctivitis may also require topical steroid drops.   Bacterial conjunctivitis is usually treated with antibiotic eye drops or ointments that cover a broad range of bacteria.   Like the common cold, there is no cure for viral conjunctivitis; however, the symptoms can be relieved with cool compresses and artificial tears (found in most pharmacies). For the worst cases, topical steroid drops may be prescribed to reduce the discomfort from inflammation. Viral conjunctivitis usually resolves within 3 weeks.   To avoid spreading infection, take these simple steps:          Disinfect surfaces such as doorknobs and counters with diluted bleach solution          Don’t swim (some bacteria can be spread in the water)          Avoid touching the face          Wash hands frequently          Don’t share towels or washcloths          Do not reuse handkerchiefs (using a tissue is best)          Avoid shaking hands

MACULAR DEGENERATION

Overview

Age-related macular degeneration (ARMD) is a degenerative condition of the macula (the central retina). It is the most common cause of vision loss in the United States in those 50 or older, and its prevalence increases with age.  AMD is caused by hardening of the arteries that nourish the retina. This deprives the sensitive retinal tissue of oxygen and nutrients that it needs to function and thrive. As a result, the central vision deteriorates.

Macular degeneration varies widely in severity.  In the worst cases, it causes a complete loss of central vision, making reading or driving impossible.  For others, it may only cause slight distortion.  Fortunately, macular degeneration does not cause total blindness since it does not affect the peripheral vision.

What is the difference between wet and dry macular degeneration?AMD is classified as either wet (neovascular) or dry (non-neovascular). About 10% of patients who suffer from macular degeneration have wet AMD. This type occurs when new vessels form to improve the blood supply to oxygen-deprived retinal tissue. However, the new vessels are very delicate and break easily, causing bleeding and damage to surrounding tissue.

Patient with wet macular degeneration develop new blood vessels under the retina.  This causes hemorrhage, swelling, and scar tissue but it can be treated with laser in some cases.

Illustration by Mark Erickson

Dry macular degeneration, although more common, typically results in a less severe, more gradual loss of vision.

The dry type is much more common and is characterized by drusen and loss of

pigment in the retina. Drusen are small, yellowish deposits that form within the layers of the retina.

What causes macular degeneration?Macular degeneration may be caused by variety of factors. Genetics, age, nutrition, smoking, and sunlight exposure may all play a role. Signs and Symptoms

Loss of central vision. This may be gradual for those with the dry type. Patients with the wet type may experience a sudden decrease of the central vision.

Difficulty reading or performing tasks that require the ability to see detail

Distorted vision (Straight lines such as a doorway or the edge of a window may appear wavy or bent.)  

Detection and Diagnosis  Eye physicians usually diagnose AMD. Vision testing, Amsler grid test, ophthalmoscopy, fundus photography and fluorescein angiography are some common tests performed during a retinal exam.

Treatment  There is no proven medical therapy for dry macular degeneration.  In selected cases of wet macular degeneration, laser photocoagulation is effective for sealing leaking or bleeding vessels. Unfortunately, laser photocoagulation usually does not restore lost vision, but it may prevent further loss. 

Recently, photodynamic therapy has proven to be effective in stopping abnormal blood vessel growth in some patients with wet AMD. This new type of laser treatment is far less damaging than laser photocoagulation and is the treatment of choice in many cases.

Early diagnosis is critical for successful treatment of wet macular degeneration. Patients can help the doctor detect early changes by monitoring vision at home with an Amsler grid.

Nutrition and macular degenerationSeveral recent studies have indicated a strong link between nutrition and the development of macular degeneration.  It has been scientifically demonstrated that people with diets high in fruits and vegetables (especially leafy green vegetables) have a lower incidence of macular degeneration.  More studies are needed to determine if nutritional supplements can prevent progression in patients with existing disease.

 Tips for AMD patients If you’ve been diagnosed with AMD, making a few simple lifestyle changes could have a positive impact on the health of your retina.  

Monitor your vision daily with an Amsler grid. By checking your vision regularly, changes that may require treatment can be detected early.

Take a multi-vitamin with zinc. (check with your eye physician for a recommendation). Antioxidants, along with zinc and lutein are essential nutrients, all found in the retina.  It is believed that people with AMD may be deficient in these nutrients.

Incorporate dark leafy green vegetables into your diet. These include spinach, collard greens, kale and turnip greens.  Always protect your eyes with sunglasses that have UV protection. Ultraviolet rays are believed to cause damage to the pigment cells in the retina.

Quit smoking. Smoking impairs the body’s circulation, decreasing the efficiency of the retinal blood vessels.

Exercise regularly. Cardiovascular exercise improves the body’s overall health and increases the efficiency of the circulatory system.

These are a few tips to make reading easier: Use a halogen light. These have less glare and disperse the light better than

standard light bulbs.  Shine the light directly on your reading material. This improves the

contrast and makes the print easier to see. Use a hand-held magnifier. A drugstore magnifier can increase the print size

dramatically. Try large-print or audio books. Most libraries and bookstores have special

sections reserved for these books. Consult a low vision specialist. These professionals are specially trained to

help visually impaired patients improve their quality of life. After a personalized consultation, they can recommend appropriate magnifiers, reading aids, practical tips, and many resources.

GLAUCOMA

Overview

Glaucoma is a disease caused by increased intraocular pressure (IOP) resulting either from a malformation or malfunction of the eye’s drainage structures.  Left untreated, an elevated IOP causes irreversible damage the optic nerve and retinal fibers resulting in a progressive, permanent loss of vision.  However, early detection and treatment can slow, or even halt the progression of the disease. 

What causes glaucoma?

The eye constantly produces aqueous, the clear fluid that fills the anterior chamber (the space between the cornea and iris).  The aqueous filters out of the anterior chamber through a complex drainage system.  The delicate balance between the production and drainage of aqueous determines the eye’s intraocular pressure (IOP). Most people’s IOPs fall between 8 and 21.  However, some eyes can tolerate higher

pressures than others. That’s why it may be normal for one person to have a higher pressure than another. 

Common types of glaucoma

Open Angle

Open angle (also called chronic open angle or primary open angle) is the most common type of glaucoma.  With this type, even though the anterior structures of the eye appear normal, aqueous fluid builds within the anterior chamber, causing the IOP to become elevated.  Left untreated, this may result in permanent damage of the optic nerve and retina.  Eye drops are generally prescribed to lower the eye pressure.  In some cases, surgery is performed if the IOP cannot be adequately controlled with medical therapy.  

Acute Angle Closure

Only about 10% of the population with glaucoma has this type.  Acute angle closure occurs because of an abnormality of the structures in the front of the eye.  In most of these cases, the space between the iris and cornea is more narrow than normal, leaving a smaller channel for the aqueous to pass through.  If the flow of aqueous becomes completely blocked, the IOP rises sharply, causing a sudden angle closure attack.

While patients with open angle glaucoma don’t typically have symptoms, those with angle closure glaucoma may experience severe eye pain accompanied by nausea, blurred vision, rainbows around lights, and a red eye. This problem is an emergency and should be treated by an ophthalmologist immediately. If left untreated, severe and permanent loss of vision will occur in a matter of days.

Secondary Glaucoma

This type occurs as a result of another disease or problem within the eye such as: inflammation, trauma, previous surgery, diabetes, tumor, and certain medications.  For this type, both the glaucoma and the underlying problem must be treated.

Congenital

This is a rare type of glaucoma that is generally seen in infants. In most cases, surgery is required. Signs and Symptoms

Glaucoma is an insidious disease because it rarely causes symptoms.  Detection and prevention are only possible with routine eye examinations.  However, certain types, such as angle closure and congenital, do cause symptoms.

Angle Closure (emergency)

Sudden decrease of vision Extreme eye pain

Headache

Nausea and vomiting

Glare and light sensitivity

Congenital

Tearing Light sensitivity

Enlargement of the cornea

Detection and Diagnosis

Because glaucoma does not cause symptoms in most cases, those who are 40 or older should have an annual examination including a measurement of the intraocular pressure.  Those who are glaucoma suspects may need additional testing.  

The glaucoma evaluation has several components. In addition to measuring the intraocular pressure, the doctor will also evaluate the health of the optic nerve (ophthalmoscopy), test the peripheral vision (visual field test), and examine the structures in the front of the eye with a special lens (gonioscopy) before making a diagnosis. 

The above photos show progressive optic nerve damage (indicated by the cup to disc ratio) caused by glaucoma.  Notice the pale appearance of the nerve with the 0.9 cup

as compared to the nerve with the 0.3 cup.

The doctor evaluates the optic nerve and grades its health by noting the cup to disc ratio.  This is simply a comparison of the cup (the depressed area in the center of the nerve) to the entire diameter of the optic nerve.  As glaucoma progresses, the area of cupping, or depression, increases.  Therefore, a patient with a higher ratio has more damage. 

The progression of glaucoma is monitored with a visual field test.  This test maps the peripheral vision, allowing the doctor to determine the extent of vision loss from glaucoma and a measure of the effectiveness of the treatment. The visual field test is periodically repeated to verify that the intraocular pressure is being adequately controlled.

The structures in the front of the eye are normally difficult to see without the help of a special gonioscopy lens.  This special mirrored contact lens allows the doctor to examine the anterior chamber and the eye’s drainage system. 

At St. Luke’s, another test called the Arden Screening Test is used to confirm the diagnosis of glaucoma. This color test may show vision changes that occur before problems appear on the visual field test.

Treatment

Most patients with glaucoma require only medication to control the eye pressure. Sometimes, several medications that complement each other are necessary to reduce the pressure adequately.

Surgery is indicated when medical treatment fails to lower the pressure satisfactorily. There are several types of procedures, some involve laser and can be done in the office, others must be performed in the operating room. The objective of any glaucoma operation is to allow fluid to drain from the eye more efficiently. 

CATARACT

What is a cataract?

When cataracts are mentioned, people often think of a film that grows on their eyes causing them to see double or blurred images. However, a cataract does not form on the eye, but rather within the eye.

Eye without a cataract Eye with a cataract

A cataract is a clouding of the natural lens, the part of the eye responsible for focusing light and producing clear, sharp images. The lens is contained in a sealed bag or capsule. As old cells die they become trapped within the capsule. Over time, the cells accumulate causing the lens to cloud, making images look blurred or fuzzy. For most people, cataracts are a natural result of aging.

In fact, they are the leading cause of visual loss among adults 55 and older. Eye injuries, certain medications, and diseases such as diabetes and alcoholism have also been known to cause cataracts.

    

Normal VisionIllustration by Mark Erickson

 

DRY EYE SYNDROME

Overview  

Dry eye syndrome is one of the most common problems treated by eye physicians.  Over ten million Americans suffer from dry eyes.  It is usually caused by a problem with the quality of the tear film that lubricates the eyes. 

Tears are comprised of three layers.  The mucus layer coats the cornea, the eye’s clear outer window, forming a foundation so the tear film can adhere to the eye.  The middle aqueous layer provides moisture and supplies oxygen and other important nutrients to the cornea.  This layer is made of 98 percent water along with small amounts of salt, proteins and other compounds.  The outer lipid layer is an oily film that seals the tear film on the eye and helps to prevent evaporation.  

Tears are formed in several glands around the eye.  The water layer is produced in the lacrimal gland, located under the upper eyelid.  Several smaller glands in the lids make the oil and mucus layers.  With each blink, the eyelids spread the tears over the eye.  Excess tears flow into two tiny drainage ducts in the corner of the eye by the nose.  These ducts lead to tiny canals that connect to the nasal passage.  The connection between the tear ducts and the nasal passage is the reason that crying causes a runny nose. 

In addition to lubricating the eye, tears are also produced as a reflex response to outside stimulus such as an injury or emotion.  However, reflex tears do little to soothe a dry eye, which is why someone with watery eyes may still complain of irritation. 

Dry eye syndrome has many causes.  One of the most common reasons for dryness is simply the normal aging process.  As we grow older, our bodies produce less oil – 60% less at age 65 then at age 18.  This is more pronounced in women, who tend to have drier skin then men.  The oil deficiency also affects the tear film.  Without as much oil to seal the watery layer, the tear film evaporates much faster, leaving dry areas on the cornea.

Many other factors, such as hot, dry or windy climates, high altitudes, air-conditioning and cigarette smoke also cause dry eyes.  Many people also find their eyes become irritated when reading or working on a computer.  Stopping periodically to rest and blink keeps the eyes more comfortable.    Contact lens wearers may also suffer from dryness because the contacts absorb the tear film, causing proteins to form on the surface of the lens.  Certain medications, thyroid conditions, vitamin A deficiency, and diseases such as Parkinson’s and Sjogren’s can also cause dryness.  Women frequently experience problems with dry eyes as they enter menopause because of hormonal changes.  

 Symptoms

Itching Burning Irritation Redness Blurred vision that improves with blinking Excessive tearing Increased discomfort after periods of reading, watching TV, or working on a

computer

Detection and Diagnosis There are several methods to test for dry eyes.  The doctor will first determine the underlying cause by measuring the production, evaporation rate and quality of the tear film.  Special drops that highlight problems that would be otherwise invisible are particularly helpful to diagnose the presence and extent of the dryness.    Treatment A treatment option - BioTears™

When it comes to treating dry eyes, everyone’s needs are a little different.  Many find relief simply from using artificial tears on a regular basis.  Some of these products are watery and alleviate the symptoms temporarily; others are thicker and adhere to the eye longer.  Preservative-free tears are recommended because they are the most soothing and have fewer additives that could potentially irritate.  Avoid products that whiten the eyes – they don’t have adequate lubricating qualities and often make the problem worse. 

Closing the opening of the tear drain in the eyelid with special inserts called punctal plugs is another option.  This works like closing a sink drain with a stopper.  These special plugs trap the tears on the eye, keeping it moist.  This may be done on a temporary basis with a dissolvable collagen plug, or permanently with a silicone plug. 

There are also simple lifestyle changes that can significantly improve irritation from dry eyes.  For example, drinking eight to ten glasses of water each day keeps the body hydrated and flushes impurities.  Make a conscious effort to blink frequently – especially when reading or watching television.  Avoid rubbing the eyes.  This only worsens the irritation. 

Treating dry eye problems is important not only for comfort, but also for the health of the cornea.  

A treatment option (BioTears)

Watch the Dry Eye Syndrome video

More about Dry Eye Syndrome

Nutrition and Dry Eye Syndrome

BLEPHARITIS (Granulated Eyelids)

Overview

Blepharitis is a common inflammatory condition that affects the eyelids.  It usually causes burning, itching and irritation of the lids.  In severe cases, it may also cause styes, irritation and inflammation of the cornea (keratitis) and conjunctiva (conjunctivitis).  Some patients have no symptoms at all. 

Blepharitis is usually a chronic problem that can be controlled with extra attention to lid hygiene.  However, it is sometimes caused by an infection and may require medication. 

 Signs and Symptoms

Sandy, itchy eyes Red and/or swollen eyelids Crusty, flaky skin on the eyelids Dandruff

 Detection and Diagnosis

Blepharitis is detected during a routine examination of the eyelids and lashes using a slit lamp microscope. 

 Treatment

The key to controlling blepharitis is to keep the eyelids and eyelashes clean.  Begin by soaking a clean washcloth in hot tap water.  (You may also warm the washcloth by dampening it first and placing it in the microwave for 15-20 seconds.  Use caution, all microwaves heat at different intensities.  Hold the washcloth to your cheek to test for temperature before placing it on the eyes.)  Place the compress on closed eyelids for five minutes, and then repeat.  Next, gently scrub the eyelids with a washcloth or cotton swab soaked in a mixture of equal parts of baby shampoo and water.  Afterward, rinse the lids thoroughly with warm water.

This treatment should be repeated two to three times daily for two weeks, and then reduced to once daily.  Like dandruff, there is no cure for blepharitis; but it can be controlled.  In some cases, anti-inflammatory and antibiotic drops or ointments are necessary for flare-ups or more severe cases. 

HERPES SIMPLEX EYE DISEASE

Overview

Herpes simplex is a very common virus affecting the skin, mucous membranes, nervous system, and the eye.  There are two types of herpes simplex.  Type I causes cold sores or fever blisters and may involve the eye.  Type II is sexually transmitted and rarely causes ocular problems.   

Nearly everyone is exposed to the virus during childhood.  Herpes simplex is transmitted through bodily fluids, and children are often infected by the saliva of an adult.  The initial infection is usually mild, causing only a sore throat or mouth.  After exposure, herpes simplex usually lies dormant in the nerve that supplies the eye and skin.  

Later on, the virus may be reactivated by stress, heat, running a fever, sunlight, hormonal changes, trauma, or certain medications.  It is more likely to recur in people who have diseases that suppress their immune system.  In some cases, the recurrence is triggered repeatedly and becomes a chronic problem.  

When the eye is involved, herpes simplex typically affects the eyelids, conjunctiva, and cornea.  Keratitis (swelling caused by the infection), a problem affecting the cornea, is often the first ocular sign of the disease.  In some cases, the infection extends to the middle layers of the cornea, increasing the possibility of permanent scarring.  Some patients develop uveitis, an inflammatory condition that affects other eye tissues.

Signs and Symptoms

Pain Red eye

Tearing

Light sensitivity

Irritation, scratchiness

Decreased vision (dependent on the location and extent of the infection)

Detection and Diagnosis

Herpes simplex is diagnosed with a slit lamp examination.  Tinted eye drops that highlight the affected areas of the cornea may be instilled to help the doctor evaluate the extent of the infection.  

Treatment

Treatment of herpes simplex keratitis depends on the severity.  An initial outbreak is typically treated with topical and sometimes oral anti-viral medication.  The doctor may gently scrape the affected area of the cornea to remove the diseased cells.  Patients who experience permanent corneal scarring as a result of severe and recurrent infections may require a corneal transplant to restore their vision.

DIABETIC RETINOPLASTY

Overview

Diabetes is a disease that occurs when the pancreas does not secrete enough insulin or the body is unable to process it properly. Insulin is the hormone that regulates the level of sugar (glucose) in the blood. Diabetes can affect children and adults.

How does diabetes affect the retina?

Patients with diabetes are more likely to develop eye problems such as cataracts and glaucoma, but the disease’s affect on the retina is the main threat to vision. Most patients develop diabetic changes in the retina after approximately 20 years. The effect of diabetes on the eye is called diabetic retinopathy.

Over time, diabetes affects the circulatory system of the retina. The earliest phase of the disease is known as background diabetic retinopathy. In this phase, the arteries in the retina become weakened and leak, forming small, dot-like hemorrhages. These leaking vessels often lead to swelling or edema in the retina and decreased vision.

The next stage is known as proliferative diabetic retinopathy. In this stage, circulation problems cause areas of the retina to become oxygen-deprived or ischemic. New, fragile, vessels develop as the circulatory system attempts to maintain adequate oxygen levels within the retina. This is called neovascularization. Unfortunately, these delicate vessels hemorrhage easily. Blood may leak into the retina and vitreous, causing spots or floaters, along with decreased vision.

In the later phases of the disease, continued abnormal vessel growth and scar tissue may cause serious problems such as retinal detachment and glaucoma.

Signs and Symptoms

The affect of diabetic retinopathy on vision varies widely, depending on the stage of the disease. Some common symptoms of diabetic retinopathy are listed below, however, diabetes may cause other eye symptoms.

Blurred vision (this is often linked to blood sugar levels

Floaters and flashes

Sudden loss of vision 

Detection and Diagnosis

Diabetic patients require routine eye examinations so related eye problems can be detected and treated as early as possible. Most diabetic patients are frequently examined by an internist or endocrinologist who in turn work closely with the ophthalmologist.

The diagnosis of diabetic retinopathy is made following a detailed examination of the retina with an ophthalmoscope. Most patients with diabetic retinopathy are referred to vitreo-retinal surgeons who specialize in treating this disease.

Treatment

Diabetic retinopathy is treated in many ways depending on the stage of the disease and the specific problem that requires attention. The retinal surgeon relies on several tests to monitor the progression of the disease and to make decisions for the appropriate treatment. These include: fluorescein angiography, retinal photography, and ultrasound imaging of the eye.

The abnormal growth of tiny blood vessels and the associated complication of bleeding is one of the most common problems treated by vitreo-retinal surgeons. Laser surgery called pan retinal photocoagulation (PRP) is usually the treatment of choice for this problem.

With PRP, the surgeon uses laser to destroy oxygen-deprived retinal tissue outside of the patient’s central vision. While this creates blind spots in the peripheral vision, PRP prevents the continued growth of the fragile vessels and seals the leaking ones. The goal of the treatment is to arrest the progression of the disease.

Vitrectomy is another surgery commonly needed for diabetic patients who suffer a vitreous hemorrhage (bleeding in the gel-like substance that fills the center of the eye). During a vitrectomy, the retina surgeon carefully removes blood and vitreous from the eye, and replaces it with clear salt solution (saline). At the same time, the surgeon may also gently cut strands of vitreous attached to the retina that create traction and could lead to retinal detachment or tears.

Patients with diabetes are at greater risk of developing retinal tears and detachment. Tears are often sealed with laser surgery. Retinal detachment requires surgical treatment to reattach the retina to the back of the eye. The prognosis for visual recovery is dependent on the severity of the detachment.

Prevention

Researchers have found that diabetic patients who are able to maintain appropriate blood sugar levels have fewer eye problems than those with poor control. Diet and exercise play important roles in the overall health of those with diabetes.

Diabetics can also greatly reduce the possibilities of eye complications by scheduling routine examinations with an ophthalmologist. Many problems can be treated with much greater success when caught early.

RUBEOSIS 

Overview

Rubeosis is a term that describes abnormal blood vessel growth on the iris and the structures in the front of the eye.  Normally there are no visible blood vessels in these areas.

When the retina has been deprived of oxygen, or ischemic, as with diabetic retinopathy or vein occlusion, abnormal vessels form to supply oxygen to the eye.  Unfortunately, the formation of these vessels obstructs the drainage of aqueous fluid from the front of the eye, causing the eye pressure to become elevated.  This usually leads to neovascular glaucoma. Signs and Symptoms

Patients' primary symptom associated with rubeosis is a gradual loss of peripheral vision related to the secondary problem of glaucoma.  Rubeosis is usually undetectable with the naked eye. Detection and Diagnosis

The doctor can diagnose rubeosis with a slit lamp microscope.  Often, a special mirrored gonioscopy lens is used to examine the blood vessel growth in the front of the eye. Treatment

The primary concern with rubeosis is the treatment of the secondary problem of glaucoma.  It is often difficult however, to control the intraocular pressure with this type of glaucoma.  Both medical and surgical treatment are often required.

 KERATOCONUS 

Overview

Keratoconus is a degenerative disease of the cornea that causes it to  gradually thin and bulge into a cone-like shape.  This shape prevents light from focusing precisely on the macula.  As the disease progresses, the cone becomes more pronounced, causing vision to become blurred and distorted.  Because of the cornea's irregular shape, patients with keratoconus are usually very nearsighted and have a high degree of astigmatism that is not correctable with glasses.

Keratoconus is sometimes an inherited problem that usually occurs in both eyes.

Signs and Symptoms

Nearsightedness Astigmatism

Blurred vision - even when wearing glasses and contact lenses

Glare at night

Light sensitivity

Frequent prescription changes in glasses and contact lenses

Eye rubbing

Detection and Diagnosis

Keratoconus is usually diagnosed when patients reach their 20's.  For some, it may advance over several decades, for others, the progression may reach a certain point and stop.  

Keratoconus is not usually visible to the naked eye until the later stages of the disease.  In severe cases, the cone shape is visible to an observer when the patient looks down while the upper lid is lifted.  When looking down, the lower lid is no longer shaped like an arc, but bows outward around the pointed cornea.  This is called Munson's sign.

Special corneal testing called topography provides the doctor with detail about the cornea's shape and is used to detect and monitor the progression of the disease.  A pachymeter may also be used to measure the thickness of the cornea.

 Treatment

The first line of treatment for patients with keratoconus is to fit rigid gas permeable (RGP) contact lenses.  Because this type of contact is not flexible, it creates a smooth, evenly shaped surface to see through. However, because of the cornea's irregular shape, these lenses can be very challenging to fit.  This process often requires a great deal of time and patience.

When vision deteriorates to the point that contact lenses no longer provide satisfactory vision, corneal transplant may be necessary to replace the diseased cornea with a healthy one.

RETINAL TEAR & DETACHMENT

Overview

Retinal Tear

Retinal tears commonly occur when there is traction on the retina by the vitreous gel inside the eye. In a child’s eye, the vitreous has an egg-white consistency and is firmly attached to certain areas of the retina. Over time, the vitreous gradually

becomes thinner, more liquid and separates from the retina. This is known as a posterior vitreous detachment (PVD).

PVDs are typically harmless and cause floaters in the eye; but in some cases, the traction on the retina may create a tear. Retinal tears frequently lead to detachments as fluids seep underneath the retina, causing it to separate and detach.

Retinal Detachment

A retinal detachment occurs when the retina’s sensory and pigment layers separate. Because it can cause devastating damage to the vision if left untreated, retinal detachment is considered an ocular emergency that requires immediate medical attention and surgery. It is a problem that occurs most frequently in the middle-aged and elderly. 

There are three types of retinal detachments. The most common type occurs when there is a break in the sensory layer of the retina, and fluid seeps underneath, causing the layers of the retina to separate. Those who are very nearsighted, have undergone eye surgery, or have experienced a serious eye injury are at greater risk for this type of detachment. Nearsighted people are more susceptible because their eyes are longer than average from front to back, causing the retina to be thinner and more fragile.

The second most common type occurs when strands of vitreous or scar tissue create traction on the retina, pulling it loose. Patients with diabetes are more likely to experience this type.

The third type happens when fluid collects underneath the layers of the retina, causing it to separate from the back wall of the eye. This type usually occurs in conjunction with another disease affecting the eye that causes swelling or bleeding.  Signs and Symptoms

          Light flashes

         “Wavy,” or “watery” vision

         Veil or curtain obstructing vision

         Shower of floaters that resemble spots, bugs, or spider webs

        Sudden decrease of vision

Detection and Diagnosis

Retinal detachments are usually found because the patient calls the doctor’s office with a symptom listed above. It is critical that these problems are reported early, because early treatment can greatly improve the chance of restoring vision.

The doctor makes the diagnosis of a retinal detachment after thoroughly examining the retina with ophthalmoscopy. The retinal surgeon’s first concern is to determine

whether the macula (the center of the retina) is attached. This is critical because the macula is responsible for the central vision. Whether or not the macula is attached determines the type of corrective surgery required and the patient’s chances of having functional vision after the operation.

Ultrasound imaging of the eye is also very useful for the doctor to see additional detail of the condition of the retina from several angles.  Treatment

There are a number of ways to treat retinal detachment. The appropriate treatment depends on the type, severity and location of the detachment.

Pneumatic retinopexy is one type of procedure to reattach the retina. After numbing the eye with a local anesthesia, the surgeon injects a small gas bubble into the vitreous cavity. The bubble presses against the retina, flattening it against the back wall of the eye. Since the gas rises, this treatment is most effective for detachments located in the upper portion of the eye. In order to manipulate the bubble into the ideal location, the surgeon may ask the patient to keep his or her head in a specific position.

The gas bubble slowly absorbs over the next 1-2 weeks. At that time, an additional procedure is usually performed to “tack down” the retina. This can be done either with cryotherapy, a procedure that uses nitrous oxide to freeze the retina, sealing it in place, or with laser. Local anesthesia is used for both procedures.

Some types of retinal detachments, because of their location or size, are best treated with a procedure called a scleral buckle. With this technique, a tiny sponge or band made of silicone is attached to the outside of the eye, pressing inward and holding the retina in position. After removing the vitreous gel from the eye with a procedure called a vitrectomy, the surgeon usually seals a few areas of the retina into position with laser or cryotherapy. The scleral buckle is not visible and remains permanently attached to the eye. This technique of reattaching the retina may elongate the eye, causing nearsightedness.

In rare cases where other types of retinal detachment surgeries are either inappropriate or unsuccessful, silicone oil may be used to reattach the retina. The vitreous gel is removed and replaced with silicone oil, which presses the retina into place. While the oil is inside the eye, the vision is extremely poor. After the retina has resealed itself against the back of the eye, a second procedure may be performed to remove the oil.

What you can do…

Early detection is key in successfully treating retinal detachments and tears. Awareness of the quality of your vision in each eye is extremely important, especially if you are in a higher-risk group such as those who are nearsighted or diabetic. Compare the vision of your eyes daily by looking straight ahead and covering one eye and then the other.

Notify your doctor immediately if you notice any of the following:

An obstruction of your peripheral vision (veil, shadow, or curtain) Sudden shower of floaters Light flashes Spider webs

Related surgical procedures:

    Vitrectomy

CYTOMEGALOVIRUS 

Overview

The cytomegalovirus (CMV) is related to the herpes virus and is present in almost everyone. Normally, most people’s immune systems are able to fight the virus, preventing it from causing problems in their bodies. However, when the immune system is suppressed because of disease (HIV), organ or bone marrow transplant, or chemotherapy, the CMV virus can cause damage and disease to the eye and the rest of the body.

 Photographs of retinas affected with CMV retinitis

CMV is the most common type of virus that infects those who are HIV positive. It affects the eye in about 30% of the cases by causing damage to the retina. This is called CMV retinitis. The likelihood of developing CMV retinitis increases as the CD4 cell count decreases.

 Normal (unaffected) retina

CMV retinitis may affect one eye at first, but usually progresses to both eyes and becomes worse as the patient's ability to fight infection decreases. The virus is sight threatening and usually requires the care and treatment of a vitreo-retinal surgeon. Patients with CMV retinitis are at risk of retinal detachment, hemorrhages, and inflammation of the retina that can lead to permanent loss of vision and even blindness.

Signs and Symptoms

CMV retinitis usually causes symptoms, but not always. Patients with a condition that suppresses the immune system should watch for the following eye symptoms while under the care of a physician.

         Floaters (spots, bugs, spider webs)

         Light flashes

         Blind spots

         Blurred vision

         Obstructed areas of vision

         Sudden decrease of vision

Detection and Diagnosis

Most patients with CMV retinitis are referred for eye treatment by another physician. The vitreo-retinal surgeon diagnoses CMV retinitis by thoroughly examining the back of the eye using ophthalmoscopy. Fluorescein angiography may be needed to evaluate the circulatory system of the retina.

Treatment

When managing CMV retinitis, the doctor’s goal is to slow the progression of the disease and to treat related eye problems. Anti-viral medications such as ganciclovir or foscarnet are often prescribed. These drugs can be administered orally, intravenously, injected directly into the eye or through an intravitreal implant.

COLORBLINDNESS

Overview

Color blindness may be a hereditary condition or caused by disease of the optic nerve or retina.  Acquired color vision problems only affect the eye with the disease and may become progressively worse over time.  Patients with a color vision defect caused by disease usually have trouble discriminating blues and yellows.   

Inherited color blindness is most common, affects both eyes, and does not worsen over time.  This type is found in about 8% of males and 0.4% of females.  These color problems are linked to the X chromosome and are almost always passed from a mother to her son.  

Color blindness may be partial (affecting only some colors), or complete (affecting all colors).  Complete color blindness is very rare.  Those who are completely color blind often have other serious eye problems as well.

Photoreceptors called cones allow us to appreciate color.  These are concentrated in the very center of the retina and contain three photosensitive pigments:  red, green and blue.  Those with defective color vision have a deficiency or absence in one or more of these pigments.  Those with normal color vision are referred to as trichromats.  People with a deficiency in one of the pigments are called anomalous trichromats (the most common type of color vision problem.)  A dichromat has a complete absence in one cone pigment.    Signs and Symptoms

The symptoms of color blindness are dependent on several factors, such as whether the problem is congenital, acquired, partial, or complete.  

Difficulty distinguishing reds and greens (most common)

Difficulty distinguishing blues and greens (less common)

The symptoms of more serious inherited color vision problems and some types acquired problems may include:

Objects appear as various shades of gray (this occurs with complete color blindness and is very rare)

Reduced vision

Nystagmus

 Detection and Diagnosis

Color vision deficiency is most commonly detected with special colored charts called the Ishihara Test Plates.  On each plate is a number composed of colored dots.   While holding the chart under good lighting, the patient is asked to identify the number.  Once the color defect is identified, more detailed color vision tests may be performed.   Treatment

There is no treatment or cure for color blindness.  Those with mild color deficiencies learn to associate colors with certain objects and are usually able to identify color as everyone else.  However, they are unable to appreciate color in the same way as those with normal color vision.

RETINITIS PIGMENTOSA

Overview

Retinitis pigmentosa (RP) is a rare, hereditary disease that causes the rod photoreceptors in the retina to gradually degenerate.  The rods are located in the periphery of the retina and are responsible for peripheral and night vision.  Cones, another type of photoreceptor, are densely concentrated in the macula.  The cones are responsible for central visual acuity and color vision.  

The disease may be X-linked (passed from a mother to her son), autosomal recessive (genes required from both parents) or autosomal dominant (gene required from one parent) trait.  Since it is often a sex-linked disease, retinitis pigmentosa affects males more than females.

People with RP usually first notice difficulty seeing in dim lighting and gradually lose peripheral vision.  The course of RP varies.  For some, the affect on vision may be mild.  Others experience a progression of the disease that leads to blindness.  

In many cases, RP is diagnosed during childhood when the symptoms begin to become apparent.  However, depending on the progression of the disease, it may not be detected until later in life. Signs and Symptoms

Difficulty seeing dim lighting Tendency to trip easily or bump into objects when in poor lighting

Gradual loss of peripheral vision

Glare

Loss of contrast sensitivity

Eye fatigue (from straining to see)

Detection and Diagnosis

Retinitis pigmentosa is usually diagnosed before adulthood.  It is often discovered when the patient complains of difficultly with night vision.  The doctor diagnoses RP by examining the retina with an ophthalmoscope.  The classic sign of RP is clumps of pigment in the peripheral retinal called "bone-spicules."  A test called electroretinography (ERG) may also be ordered to study the eye's response to light stimuli.  The test gives the doctor information about the function of the rods and cones in the retina. 

Illustration by Mark Erickson

 Treatment

There is currently no standard treatment or therapy for retinitis pigmentosa; however, scientists have isolated several genes responsible for the disease.  Once RP is discovered, patients and their families are encouraged to seek genetic counseling.

Current Research 

Scientists at Johns Hopkins University are developing a micro-computer chip prosthesis called the Multiple-unit Artificial Retina Chipset (MARC).  Once implanted in the retina, the chip transmits images to the brain that are captured from a small camera mounted on the patient's glasses.  The chip is still in development and is not yet available for widespread use.

Doctors continue to search for treatments for RP but have yet to find a cure.

CORNEAL ULCER

Overview

A corneal ulcer forms when the surface of the cornea is damaged or compromised.  Ulcers may be sterile (no infecting organisms) or infectious.  The term infiltrate is also commonly used along with ulcer.   Infiltrate refers to an immune response causing an accumulation of cells or fluid in an area of the body where they don't normally belong.

Whether or not an ulcer is infectious is an important distinction for the physician to make and determines the course of treatment.  Bacterial ulcers tend to be extremely painful and are typically associated with a break in the epithelium, the superficial layer of the cornea.  In some cases, the inflammatory response involves the anterior chamber along with the cornea.  Certain types of bacteria, such as Pseudomonas, are extremely aggressive and can cause severe damage and even blindness within 24-48 hours if left untreated.  

Sterile infiltrates on the other hand, cause little if any pain.  They are often found near the peripheral edge of the cornea and are not necessarily accompanied by a break in the epithelial layer of the cornea.

There are many causes of corneal ulcers.  Contact lens wearers (especially soft) have an increased risk of ulcers if they do not adhere to strict regimens for the cleaning, handling, and disinfection of their lenses and cases.  Soft contact lenses are designed to have very high water content and can easily absorb bacteria and infecting organisms if not cared for properly.  Pseudomonas is a common cause of corneal ulcer seen in those who wear contacts.  

Bacterial ulcers may be associated with diseases that compromise the corneal surface, creating a window of opportunity for organisms to infect the cornea.  Patients with severely dry eyes, difficulty blinking, or are unable to care for themselves, are also at risk.  Other causes of ulcers include:  herpes simplex viral infections, inflammatory diseases, corneal abrasions or injuries, and other systemic diseases.

Signs and Symptoms

The symptoms associated with corneal ulcers depend on whether they are infectious or sterile, as well as the aggressiveness of the infecting organism.

Red eye  Severe pain (not in all cases)

Tearing

Discharge 

White spot on the cornea, that depending on the severity of the ulcer, may not be visible with the naked eye

Light sensitivity

Detection and Diagnosis

Corneal ulcers are diagnosed with a careful examination using a slit lamp microscope.  Special types of eye drops containing dye such as fluorescein may be instilled to highlight the ulcer, making it easier to detect.  

If an infectious organism is suspected, the doctor may order a culture.  After numbing the eye with topical eye drops, cells are gently scraped from the corneal surface and tested to determine the infecting organism.

Treatment

The course of treatment depends on whether the ulcer is sterile or infectious.  Bacterial ulcers require aggressive treatment.  In some cases, antibacterial eye drops are used every 15 minutes.  Steroid medications are avoided in cases of infectious ulcers.  Some patients with severe ulcers may require hospitalization for IV antibiotics and around-the-clock therapy.  Sterile ulcers are typically treated by reducing the eye's inflammatory response with steroid drops, anti-inflammatory drops, and antibiotics. 

STRABISMUS

(CROSSED OR TURNED EYE)

Overview

Strabismus is a problem caused by one or more improperly functioning eye muscles, resulting in a misalignment of the eyes.  Normally, each eye focuses on the same spot but sends a slightly different message to the brain.  The brain superimposes the two images, giving vision depth and dimension.  Here's an easy way to see how the eyes work together:  hold your finger at arm's length.  While looking at your finger, close one eye, then the other.  Notice how your finger changes position.  Even though the images are slightly different, the brain interprets them as one.

Each eye has six muscles that work in unison to control movements.  The brain controls the eye muscles, which keep the eyes properly aligned.  It is critical that the muscles function together for the brain to interpret the image from each eye as a single one.

Strabismus must be detected early in children because they are so adaptable.  If a child sees double, his or her brain quickly learns to suppress or block out one of the images to maintain single vision.  In a very short time, the brain permanently suppresses vision from the turned eye, causing a weak or amblyopic eye.  Children may also develop a head tilt or turn to compensate for the problem and eliminate the double image.  Unlike children, adults with a newly acquired strabismus problem typically see double.

There are many causes of strabismus.  It can be inherited, or it may be caused by trauma, certain diseases, and sometimes eye surgery.  Signs and Symptoms

Adults are much more likely to be bothered by symptoms from strabismus than young children.  It is unusual for a child to complain of double vision.  Children should undergo vision screening exams to detect problems early.  The younger the child is when strabismus is detected and treated, the better the chance of normal vision.  The following are common signs and symptoms:

Turned or crossed eye Head tilt or turn

Squinting

Double vision (in some cases)

Detection and Diagnosis

Strabismus is detected with a comprehensive eye exam and special tests used to evaluate the alignment of the eyes such as: the Krimsky test and prism testing.  Treatment

The appropriate treatment for strabismus is dependent on several factors including the patient's age, the cause of the problem, and the type and degree of the eye turn.  Treatment may include patching, corrective glasses, prisms, or surgery.

With patching, the better eye is covered, forcing the child to use the weaker eye.  Over time, the brain adjusts to using the weaker eye and vision gradually improves.  For this treatment to be effective, it must be done at a young age before the child can develop amblyopia.

Surgery is sometimes performed for both adults and children to straighten a crossed eye.  The procedure may be done with local or general anesthesia.  There are several different surgical techniques used to correct strabismus.  The appropriate one is dependent on the muscle involved and the degree of the eye turn.

CHALAZION 

Overview

A chalazion (stye) is a small lump in the eyelid caused by obstruction of an oil producing or meibomian gland.  Chalazia may occur in the upper or lower lids, causing redness, swelling and soreness in some cases. 

 Signs and Symptoms

Raised, swollen bump on the upper or lower eye lid Often red May be tender and sore

 Diagnosis

Patients often request an examination after an episode of pain and swelling of the lid.  The doctor can make the diagnosis during a simple examination of the eyelids.   Treatment

In the early stages, chalazia may be treated at home with the repeated use of warm compresses for 15 - 20 minutes followed by several minutes of light lid massage.  This helps to reduce the swelling and makes the lid more comfortable. However, if the chalazion does not diminish or recurs, medical attention may be necessary.  This may include draining the chalazion along with the use of antibiotic and anti-inflammatory medications.

AMBYLOPIA

Overview

Amblyopia is a term used to describe an uncorrectable loss of vision in an eye that

appears to be normal.  It’s commonly referred to as “lazy eye” and can occur for a variety of reasons. 

A child’s visual system is fully developed between approximately the ages of 9-11. Until then, children readily adapt to visual problems by suppressing or blocking out the image.  If caught early, the problem can often be corrected and the vision preserved.  However, after about age 11, it is difficult if not impossible to train the brain to use the eye normally. 

Some causes of amblyopia include:  strabismus (crossed or turned eye), congenital cataracts, cloudy cornea, droopy eyelid, unequal vision and uncorrected nearsightedness, farsightedness or astigmatism.  Amblyopia may occur in various degrees depending on the severity of the underlying problem.  Some patients just experience a partial loss; others are only able to recognize motion.

Patients with amblyopia lack binocular vision, or stereopsis – the ability to blend the images of both eyes together.  Stereopsis is what allows us to appreciate depth.  Without it, the ability to judge distance is impaired.

Signs and Symptoms Poor vision in one or both eyes Squinting or closing one eye while reading or watching television Crossed or turned eye Turning or tilting the head when looking at an object

Note:  Children rarely complain of poor vision.  They are able to adapt very easily to most visual impairments.  Parents must be very observant of young children and should have a routine eye exam performed by the age of 2-3 to detect potential problems.

Detection and Diagnosis   When amblyopia is suspected, the doctor will evaluate the following:  vision, eye alignment, eye movements, and fusion (the brain’s ability to blend two images into a single image).    Treatment    The treatment for amblyopia depends on the underlying problem.  In some cases, the strong eye is temporarily patched so the child is forced to use the weaker eye.  For children with problems relating to a refractive error, glasses may be necessary to correct vision.  Problems that impair vision such as cataracts or droopy eyelids often require surgery.  Regardless of the treatment required, it is of utmost importance that intervention is implemented as early as possible before the child’s brain learns to permanently suppress or ignore the eye. 

ASTIGMATISM

Overview

Astigmatism means that the cornea is oval like a football instead of spherical like a basketball. Most astigmatic corneas have two curves – a steeper curve and a flatter curve. This causes light to focus on more than one point in the eye, resulting in blurred vision at distance or near. Astigmatism often occurs along with nearsightedness or farsightedness.

Illustration by Mark Erickson

 Signs and Symptoms

         Blurred vision (near and distance)

 Detection and Diagnosis

Astigmatism can be detected and measured with corneal topography, keratometry, vision testing and refraction.

 Treatment

Astigmatism can be corrected with glasses, contacts, or surgically. The most common surgeries used to correct astigmatism are astigmatic keratotomy (procedures that involve placing a microscopic incision on the eye) and LASIK. The objective of these procedures is to reshape the cornea so it becomes more spherical or uniformly curved.

COMPUTER VISION SYNDROME

Overview

Computer vision syndrome (CVS) is a term that describes eye-related problems and the other symptoms caused by prolonged computer use.  As our dependence on computers continues to grow, an increasing number of people are seeking medical attention for eye strain and irritation, along with back, neck, shoulder, and wrist soreness.  

These problems are more noticeable with computer tasks than other near work because letters on the screen are formed by tiny dots called pixels, rather than a solid image.  This causes the eye to work a bit harder to keep the images in focus.  

Magnified view of a printed letter

 

Magnified view of a letter on a computer

screen

There is no scientific evidence that computer screens are harmful to the eyes.  A common myth is that too eye strain caused by reading and close work is damaging to the eyes.  This is not true; however, those who work at computers often experience many frustrating symptoms. 

 

DACROCYSTITIS

Overview

Dacryocystitis is an infection of the tear sac that lies between the inner corner of the eyelids and the nose. It usually results from blockage of the duct that carries tears from the tear sac to the nose. The blocked duct harbors bacteria and becomes infected. Dacryocystitis may be acute (sudden onset) or chronic (frequently recurs). It may be related to a malformation of the tear duct, injury, eye infection, or trauma. 

This problem is most common in infants because their tear ducts are often underdeveloped and clog easily. Babies often have recurrent episodes of infection; however, in most cases, the problem resolves as the child grows. In adults, the infection may originate from an injury or inflammation of the nasal passages. In many cases, however, the cause is unknown.

 Signs and Symptoms

Generally affects one eye Excessive tearing

Tenderness, redness, and swelling

Discharge

Red, inflamed bump on the inner corner of the lower lid

 Detection and Diagnosis

During the exam, the doctor will determine the extent of the blockage. Cultures may be taken of the discharge to identify the type of infection. The doctor will also determine whether the infection has affected the eye.

 Treatment

The treatment for dacryocystitis is dependent on the person's age, whether the problem is chronic or acute, and the cause of the infection. 

Infants are usually treated first by gently massaging the area between the eye and nose to help open the obstruction along with antibiotic drops or ointments for the infection. Surgery may be necessary to clear the obstruction if medical treatment is not effective and the problem persists over several months.

Before surgery, the doctor may treat the child with antibiotics to make sure the infection is cleared. The operation is performed under general anesthesia. The tear duct is gently probed to open the passage.

For adults, the doctor may clear the obstruction by irrigating the tear duct with saline. Surgery is sometimes necessary for adults if irrigation, or antibiotics fail to resolve the infection or if the infection becomes chronic. In these cases, dacryocystorhinostomy (DCR) is performed under general anesthesia to create a new passage for the tear flow.

FARSIGHTEDNESS (Hyperopia)

Overview

Farsightedness or hyperopia, occurs when light entering the eye focuses behind the retina, instead of directly on it. This is caused by a cornea that is flatter, or an eye that is shorter, than a normal eye. Farsighted people usually have trouble seeing up close, but may also have difficulty seeing far away as well.

Young people with mild to moderate hyperopia are often able to see clearly because their natural lens can adjust, or accommodate to increase the eye’s focusing ability. However, as the eye gradually loses the ability to accommodate (beginning at about 40 years of age), blurred vision from hyperopia often becomes more apparent.

Signs and Symptoms

Difficulty seeing up close

Blurred distance vision (occurs with higher amounts of hyperopia) Eye fatigue when reading Eye strain (headaches, pulling sensation, burning) Crossed eyes in children

Detection and Diagnosis

Hyperopia is detected with a vision test called a refraction. Young patients’ eyes are dilated for this test so they are unable to mask their farsightedness with accommodation. This is called a wet refraction.

Treatment

The treatment for hyperopia depends on several factors such as the patient’s age, activities, and occupation. Young patients may or may not require glasses or contact lenses, depending on their ability to compensate for their farsightedness with accommodation. Glasses or contact lenses are required for older patients.

Refractive surgery is an option for adults who wish to see clearly without glasses. LASIK, Clear Lens Extraction And Replacement, LTK and intraocular contact lenses are all procedures that can be performed to correct hyperopia.

PTOSIS

Overview

Ptosis (pronounced toe' sis), or drooping of the upper eyelid, may occur for several reasons such as: disease, injury, birth defect, previous eye surgery and age. In most cases, it is caused by either a weakness of the levator muscle (muscle that raises the lid), or a problem with the nerve that sends messages to the muscle. 

Children born with ptosis may require surgical correction of the lid if it covers the pupil. In some cases, it may be associated with a crossed or misaligned eye (strabismus). Left untreated, ptosis may prevent vision from developing properly, resulting in amblyopia, or lazy eye.

Patients with ptosis often have difficult blinking, which may lead to irritation, infection and eyestrain.  If a sudden and obvious lid droop is developed, an ophthalmologist should be consulted immediately.  

Signs and Symptoms

The causes of ptosis are quite diverse.  The symptoms are dependent on the underlying problem and may include:

Drooping lid (may affect one or both eyes) Irritation  Difficulty closing the eye completely Eye fatigue from straining to keep eye(s) open Children may tilt head backward in order to lift the lid

Crossed or misaligned eye Double vision

 Detection and Diagnosis

When examining a patient with a droopy lid, one of the first concerns is to determine the underlying cause.  The doctor will measure the height of the eyelid, strength of the eyelid muscles, and evaluate eye movements and alignment.  Children may require additional vision testing for amblyopia. 

Treatment 

Ptosis does not usually improve with time, and nearly always requires corrective surgery by an ophthalmologist specializing in plastic and reconstructive surgery.  In most cases, surgery is performed to strengthen or tighten the levator muscle and lift the eyelid.  If the levator muscle is especially weak, the lid and eyebrow may be lifted.  Ptosis can usually be performed with local anesthesia except with young children. 

RETINAL VEIN OCCLUSION

Overview

Retinal vein occlusion occurs when the circulation of a retinal vein becomes obstructed by an adjacent blood vessel, causing hemorrhages in the retina. Swelling and ischemia (lack of oxygen) of the retina as well as glaucoma are fairly common complications.

The visual symptoms can vary in severity from one person to the next, and are dependent on whether the central retinal vein or a branch retinal vein is involved. Patients who experience a branch vein occlusion often notice a gradual improvement in their vision as the hemorrhage resolves. Recovery from a central vein occlusion is much less likely since it affects the macula.

This problem appears equally in males and females and is more common after the age of 60.  Symptoms

Sudden onset Blurred or missing area of vision (if a branch vein is involved)

Severe loss of central vision (if a central vein is involved)  

 Detection and Diagnosis

Vein occlusion is diagnosed by examining the retina with an ophthalmoscope. Fluorescein angiography may be performed in some cases to study the circulation of the retina and to determine the extent of macular edema or swelling.

Treatment

Following a vein occlusion, the primary concern is to treat the secondary complications. If areas of the retina are oxygen-deprived, LASER may be used to prevent growth of delicate vessels that could break, bleed or cause glaucoma.

The following are common risk factors for vein occlusion:

         Diabetes          Hypertension          Cardiovascular disease  

RESEARCHES / RELATED ISSUES

Januray 2005

Do Mobile Phones Cause Eye Cancer?

Eye Surgeons Question the Connection

Scientists have long questioned the possible link between certain types of brain cancer and cell phone use.  The concern surrounding mobile phones lies in the fact that they emit low levels of radiofrequency energy - the same type that radiates from microwaves.  However, despite extensive ongoing research, the Food and Drug Administration has yet to find scientific evidence supporting a link between the two.   

Cell Phones and Eye Cancer...

A recent study published in the journal Epidemiology, suggested a connection between a type of eye cancer called uveal melanoma and cellular phone use.  Uveal melanoma affects the eye's uveal tract:  the iris, ciliary body and choroid.  The study, conducted in Germany, compared the cell phone usage patterns of 118 people known to have the eye cancer and 475 people with healthy eyes.  The investigators did not know if they were examining a healthy person, or one with eye cancer.  

After questioning each group regarding their mobile phone use and habits, they concluded that those with eye cancer had used the phones at higher rates than those without cancer.  Even though the study was published, the head researcher admitted that further investigation is needed before concluding that the phones caused the cancer.

St. Luke's vitreo-retinal surgeon Dan Montzka, MD, agrees that more evidence is needed.  "I think it's quite a leap to make a correlation between uveal melanoma and cell phone use based on this study alone.  I think the FDA's case control studies will give us much more definitive information."

The FDA agrees that there has been precious little evidence that clearly supports the hypothesis.  Research done on rats and mice is very difficult to correlate to humans, and studies comparing the healthy to those with cancer have yet to turn up any conclusive evidence.

Until the ongoing research is complete, the FDA offers a few suggestions for concerned individuals:

Mobile phone with an antenna located outside the car Hand-held phone with a built-in antenna connected to an external antenna

mounted outside the car

Headset with a remote antenna (the phone is carried at the waist)

Sources:  The Sunday Times, Jan. 14, 2001; www.fda.gov

High Levels Of Amino Acid May Be Biomarker For Increased Risk Of Age-Related Macular Degeneration

People who have elevated homocysteine in their blood, an amino acid which is a known biomarker for cardiovascular disease, may also be at an increased risk of developing age-related macular degeneration (AMD), according to a study in the January issue of the American Journal of Ophthalmology.

Researchers measured the fasting plasma homocysteine levels of 934 individuals who were participating in an ancillary study of the Age-Related Eye Disease Study. Five hundred and forty seven people with AMD and 387 control subjects were tested at the Massachusetts Eye and Ear Infirmary (Boston, Massachusetts.) and Devers Eye Institute (Portland, Oregon).

“We found that elevated homocysteine in the blood may be another biomarker for increased risk of AMD,” said lead author Johanna M. Seddon, M.D., director of Epidemiology at the Massachusetts Eye and Ear Infirmary who is also an associate professor of ophthalmology at Harvard Medical School and at the Harvard School of Public Health. “Homocysteine can be reduced by dietary intake of vitamins B6, B12 and folate, so the relationship between this amino acid and AMD deserves further study.”

Dr. Seddon's finding adds to the growing body of evidence that there may be overlapping disease mechanisms between AMD and cardiovascular diseases.

Dr. Seddon and her colleagues first proposed this potential relationship between homocysteine and AMD in the mid-1990s and published this hypothesis in a review article in 1999. She and her team previously established that smoking and nutrition are modifiable factors associated with the development and progression of AMD. They are now also searching for the genes involved in the etiology of this increasing cause of blindness.

Adapted from the following source: Massachusetts Eye and Ear Infirmary

Dr. Seddon is an Ad Hoc member of the Scientific Review Committee for Macular Degeneration Research, a program of the American Health Assistance Foundation. We are proud to have previously funded Dr. Seddon’s research concerning biological markers of inflammation and their correlation with the progression of age-related macular degeneration.

Sutureless Technique Simplifies Retinal Surgery

Retina surgery patients enjoy the benefits of no-stitch incisions

Since the early 1990's, cataract surgeons have operated through incisions that didn't need to be sutured after the procedure.  Soon after it was introduced, the technique caught on, and practically revolutionized cataract surgery.  "No-stitch incisions opened the door for surgical innovations, new instrumentation and breakthroughs in anesthesia," explains Dr. Rowsey.  "Plus, the patients benefited by getting a safer procedure and faster recovery."  

Prompted by an interest in reducing patients' recovery time, doctors at St. Luke's integrated self-sealing incisions with vitrectomy - a procedure that is often performed along with other vitreo-retinal surgeries.  The tiny 2 millimeter incisions used for the procedure, known as sclerotomies, are made on the scleral tissue.  Most vitreo-retinal surgeries require 3 sclerotomies:  one for the line that keeps the eye inflated with fluid, a second for the light source, and a third for the surgical instrument.  Because of the way the incision is constructed, it seals naturally from the eye's internal pressure.  

After introducing the self-sealing sclerotomies in 1996 at the Vitreous Society Meeting in New Orleans, other vitreo-retinal surgeons adopted the technique.  Today, doctors at St. Luke's have performed self-sealing sclerotomies for more than 2,000 vitrectomy surgeries with no serious complications.  "Our goal is take

a minimalist approach to surgery.  That translates to less time in the operating room, and it reduces the recovery, swelling and discomfort,".  

The St. Luke's retinal team has also discovered that when applied to scleral buckling surgery, a procedure used to repair retinal detachment, patients enjoy similar benefits.  "We used to suture a band on the eye to push the retina into place.  Now, we thread the band like a belt through tiny stitchless scleral tunnels that resemble belt loops," explains Dr. Montzka.  

Aside from the benefits to the patient, this technique often makes surgery easier to perform.  "There are times that I need to work in very awkward positions," says Dr. Montzka.  "Sutureless incisions give me more flexibility because I can easily swap the position of the instruments from one sclerotomy to the other with no problem."

"It's always exciting to refine techniques that lead to better care for the patient and to share these with other surgeons looking for better ways to do things,".  The St. Luke's doctors plan to teach the technique to other surgeons at ophthalmic symposiums later this year. 

Cataract Formation Linked to Smoking

Study concludes that giving up cigarettes can reduce the risk of cataracts

In a study of nearly 21,000 U.S. male physicians, spanning an average of 13.6 years, researchers found a direct link between smoking and the development of cataracts.  The study, known as Physicians Health Study I, evaluated physicians between the ages of 40 and 84 who had no prior history of cataracts before 1982.  

Participants were asked to complete questionnaires that included information such as: number of cigarettes smoked daily, age when they started smoking, and their age if they stopped smoking.  Each participant received annual eye exams and were required to report the results to the study investigators.  The participants' ophthalmologists and optometrists confirmed the results.  Adjustments were made to account for other cataract risk factors.  

Decreased incidence of cataract among past smokers 

Past smokers were grouped by the number of years they had stopped smoking. The participants who were past smokers were found to have a 23% less risk of cataracts when compared with current smokers; however, they still had a greater risk of developing cataracts than those who had never smoked.  Also of interest is that the past smokers were found to be in better health than smokers and lead more healthy lifestyles.  

Smoking has also been linked to eye diseases such as age-related macular degeneration.  St. Luke's surgeon J. James Rowsey, MD hopes that research such as the Physicians Health Study will make smokers think twice before lighting up.  "We learn more every day about the harmful affects smoking has on the body, but not many people realize the connection between smoking and their vision.  Young people who quit while they're ahead are very lucky because much of the damage is reversible.  Long-time smokers on the other hand, aren't always as fortunate." 

What's in a Name?

Find out what the initials after your eye care professional's name mean

Ever wonder about the qualifications of the people who examine your eyes?  Confused by all those O's -- optician, optometrist, ophthalmologist, ocularist, orthoptist?  Find out what these titles mean and more.  

Ophthalmologist (MD or DO):  An ophthalmologist is a medical doctor whose training includes:  bachelor degree, 4 years of medical school, a 1-year internship, and a 3-4 year residency program.  Many doctors continue their education with a 1-2 year fellowship that concentrates on a particular subspecialty such as glaucoma or retinal disease.  Ophthalmologists are trained to diagnose and treat eye diseases and conditions with medications and surgery.  

Optometrist (OD):  An optometrist has acquired a bachelor's degree, and completed 4 years of additional education at an accredited school of optometry.  Optometrists specialize in prescribing and fitting glasses and contact lenses as well as the detection and diagnosis of eye diseases.  Optometrists often work with ophthalmologists to manage diseases and to care for patients following eye surgery.

Ocularist:  An ocularist is specially trained to fit prosthetic (artificial) eyes after surgery or to cover disfigurements.  Ocularists must complete a 5 year apprentice program and pass a board examination for certification.

Orthoptist (CO):  Orthoptists specialize in evaluating the visual system and muscle function, especially with infants, children, and young people.  They work along with optometrists and ophthalmologists to provide non-surgical treatments to correct muscle imbalances and associated eye problems.  An orthoptist must complete 2 years of specialized training as well as a board examination.  

Optician (ABOC - American Board of Opticianry Certified and NCLC - Certified National Contact Lens Examiner):  An optician is specially trained to make and fit eyeglasses.  Opticians require 2 years of training prior to sitting for a board examination.  Some opticians also become certified in contact lens fitting.

Allied health personnel (COA, COT, COMT):  Ophthalmic medical personnel assist the physician in the diagnosis of conditions, treatment of disease and injury, and care of patients.  The Joint Commission on Allied Health Personnel grants certification at three difference levels after passing a board examination and skill test:  certified ophthalmic assistant (COA), certified ophthalmic technician (COT), and certified ophthalmic medical technologist (COMT).  Each level of certification requires additional education, skill and experience over the previous level.  

Certified Ophthalmic Retinal Photographer (CRA):  Certified ophthalmic photographers specialize in photography of the eye used for diagnosis and documentation.  Individuals may become certified by sitting for a board examination and passing a skill evaluation. 

Ophthalmic Registered Nurse (ORN):  An ophthalmic registered nurse has received special training and certification ophthalmology in addition to his or her nursing education of 2-4 years.