Occupational

eye disorders

History

vision before and after the injury

visual loss was sudden or gradual

presence of a foreign body is suspected, the worker should be asked about the

type of material that might be involved (a magnetic metal such as iron or steel, a

nonmagnetic metal such as aluminum or copper, or an organic material such as

wood) because this information is helpful for determining the method of

treatment and for prognosis

Soluble metallic salts from iron-or copper-containing foreign bodies can cause

irreversible toxic damage to the retina, best prevented by their prompt removal.

Less-soluble materials, such as aluminum, plastic, or glass, are associated with a

better prognosis

Organic foreign bodies, such as pieces of wood or splinters of plant

material, may introduce an intraocular infection that frequently is

difficult to treat and has a very poor prognosis

ocular pain, irritation, itching, or periocular swelling. Severe pain

and photophobia (light-induced pain) in a red eye suggest

intraocular involvement and warrant immediate ophthalmologic

evaluation. Discharge from the eye is caused by conjunctival

irritation or conjunctivitis. Itching is typical of allergic reactions.

Blurred vision, difficulties in seeing, ergonomic and spectacle

problems are other common complaints

Evaluation

evaluation prior to employment is important to

determine the worker’s capacity to perform in that

work

In the evaluation not only are measurements made

but also the worker’s vision is assessed in terms of

the requirements of each particular occupation.

Examination

A. External Eye Examination:

1. Eyelids

symmetry of the lids of both eyes

lacerations that cross the lid margins

Except in the case of a suspected ruptured or lacerated globe, the lid can be everted to

search for foreign bodies on the upper tarsus.

2. Orbits

Palpate the orbital rims, and note discontinuities and

crepitus caused by subcutaneous air from fractures of the paranasal sinuses

3. Conjunctiva

o examine the conjunctiva, evert the lids by applying gentle pressure over the

superior orbital rim of the upper lid or over the malar eminence of the lower lid,

Inflammation caused by trauma usually produces a watery discharge (tears), in

contrast to the purulent mucoid discharge of bacterial conjunctivitis. Viral or

chlamydial conjunctivitis is characterized by lymph follicles in the inferior fornix

of the conjunctival sac along with a watery discharge

4. Corneas

light reflection on the normally smooth corneal surface

A fluorescein paper strip moistened with sterile saline or a topical anesthetic can be

used to stain the tears on the surface . The stain diffuses into any area of disrupted

epithelium and stains it bright green

5. Anterior chambers

Hyphema (hemorrhage into the anterior chamber) is almost

always a sign of significant injury

Hypopyon (purulent material in the anterior chamber) is

characterized by a white or gray layer of inflammatory

cells at the chamber bottom

6. Pupils

round, black, and equal in size

Pupillary reactions to light

B. Test of Ocular Motility

Limitation of upward or downward gaze occurs frequently

in orbital floor fractures and may be the result of

accompanying edema or mechanical restriction

C. Ophthalmoscopic Examination

1. Red reflex

darkened room with the instrument set at 0 or +1, and the eyes should be observed

at arm’s length, approximately 60 cm (2 ft), so that the reflex in both of them can

be seen at the same time and compared

2. Optic discs

presence of papilledema. Optic discs usually are well vascularized and have a

good pink color

3. Optic cups

The width of each optic cup is usually one-third or less the diameter of the whole

optic disc. If it is as large as half the diameter, or if the optic cups are not similar

in both eyes, there is an increased risk for glaucoma

4. Retinal vessels

The vessels should be examined along the upper and lower arcades

proceeding from the optic disc, and the presence of

hemorrhages, exudates

5. Maculae and foveae

Each macula should be checked for alterations in its usual

relatively featureless appearance. Its center, the fovea, always can be

located 2.5 disc diameters temporal to the optic disc. Its concave

center usually shows a small, bright foveal light reflex

D. Measurement of Intraocular Pressure

measured with a Schiotz tonometer or with an applanation tonometer

Angle-closure glaucoma accounts for only approximately 5% of all

glaucoma; it usually presents with acute aching pain in the involved eye

with moderate redness of the globe and blurred vision, sometimes

described as colored halos around bright lights

Angle-closure glaucoma can occur only in eyes with anatomically

shallow anterior chambers and narrow chamber angles .pilocarpine 1–4%

every 15 minutes for 1–2 hours The production of aqueous humor is

reduced with a topical ophthalmic β-adrenergic blocker and a carbonic

anhydrase inhibitor

Intravenous urea or mannitol infusions are effective, but oral ingestion of glycerin is as effective, safer, and more easily available

Open-angle glaucoma accounts for most cases of glaucomatous visual loss (90%). Its onset is insidious, there is no pain, and visual symptoms are noticed only after severe irreversible loss of visual field has occurred

Open-angle glaucoma accounts for most cases of glaucomatous visual loss (90%). Its onset is insidious, there is no pain, and visual symptoms are noticed only after severe irreversible loss of visual field has occurred

E. Test of Visual Acuity

measured with a Snellen chart, if possible, or with a near-acuity card

and recorded appropriately. Each eye should be tested separately,

first without correction (glasses or contact lenses) and then

with correction;

The Landolt C optotype and number charts are universally accepted,

but the EDTRS and the old Snellen chart are also acceptable in the

United States. Luminance at the chart needs to be 80 candelas per

square meter or higher.

If visual acuity is poor and a refractive error is suspected, the chart or card can be read through a pinhole as a substitute for corrective lenses

If acuity is less than 20/200, the greatest distance at which fingers can be counted

the greatest distance at which hand movements

If vision is poorer than this, light perception can be tested

Metric visual acuity charts use 6 m as the standard test distance; therefore, 6/6 = 20/20

The peak of the light-sensitivity curve of the eye is at a wavelength of about 555 nm. This means that our best vision is in yellow-green light.

Snellen chart

EDTRS

Landolt c

Color vision Color vision appears to be particularly sensitive to toxic exposures, including a

number of different solvents, mercury, and certain pharmaceuticals

There are two types of color vision tests: screening tests and quantitative tests:

Screening tests such as Ishihara pseudoisochromatic plates and Waggoner H-R-R

plates are designed to detect even minor inherited deviations of color perception

The Ishihara plates detect only red–green confusion while the Waggoner H-R-R

plates detect blue–yellow defects also.

The severity of color vision deficiency of a healthy worker is assessed using the

Farnsworth Panel D-15 test, the Good-Lite 16 Hue test or the Lanthony

desaturated test that utilize arranging color pigments so they are adjacent to colors

of similar hue

Waggoner HRR

Farnworth D-15 Panel

Good-Lite 16 Hue test

Farnsworth-Munsell 100 Hue test is used in diagnostic

work when lesions in the retina or in the pathways are

suspected. Each eye is tested separately. This test is

more cumbersome and time consuming to administer

and more costly to run, but is helpful in assessing

changes due to neurotoxic substances

All color vision tests must be used under daylight type

During the last 10 years color vision changes have

continued to be reported due to exposure to styrene,

toluene, perchlorethylene, carbon disulfide, metallic

mercury, and mercury vapor.

F. Test of Visual Fields

Visual fields should be tested, especially in patients with

suspected head injury or a significant decrease in visual acuity.

Each eye is tested separately by confrontation. The patient is asked

to look at the examiner’s eye while the examiner’s hand moves

toward the center of the visual field.

Automated visual fields and Goldmann visual fields provide

quantitative techniques to evaluate visual fields; islands of loss of

vision (scotomas) within the visual field can be documented. Field

defects in the lower part of the visual field increase risk of accident,

Contrast Sensitivity Testing

Hamilton-Veale Contrast Sensitivity Test

Disorders of the cornea and conjunctiva

Allergic conjunctivitis Allergic conjunctivitis occurs in nearly all occupations and is caused

by a long list of workplace and other environmental allergens

If there are no known workplace antigens or irritants but symptoms

worsen at work, dry eyes from low humidity in the workplace or

decreased blinking during near work activities may be contributing

to the symptoms.

mucous discharge, dryness, itching, burning, foreign body

sensation, and tearing.

Thin threads of mucus in the lower fornix are almost pathognomonic

of an allergic reaction.

Chronic blepharitis is common and must be treated before diagnostic testing for allergic

conjunctivitis is possible. Treatment includes warm compresses and ointments, which

contain hydrocortisone, gently rubbed on the lid margin in the evening. If thick cheesy

discharge can be expressed from the meibomian glands the use of systemic tetracycline is

considered.

The case history is key in determining the likely etiology of allergic conjunctivitis. The type

and duration of symptoms during working days and weekends should be recorded

Environmental factors should be noted, including ventilation, sources of irritating and

allergic exposures, such as carpeting, cleaning agents, smoking, various chemicals used in

the workplace (including those used by adjacent workers)

artificial tears

n any treatment, avoidance of any preservatives in the medications used, especially

benzalconium chloride, is important. Topical mast-cell stabilizers and antihistamines are

effective

because of the possibility of increased intraocular pressure, potentiation of herpetic or

fungal keratitis, and of cataract formation, topical steroids should be prescribed only by an

ophthalmologist

Dry eye syndrome

the symptoms are often worsened by low humidity at the workplace

Symptoms are similar to those of allergic conjunctivitis and generally

worsen as the day goes on and with near vision tasks

Exposure to tertiary amines may cause corneal opacities. Trimethylamine

is used in the synthesis of choline, tetramethylammonium hydroxide, plant

growth regulators or herbicides, strongly basic anion exchange resins, dye

leveling agents and a number of basic dye

Triphenylamine is an organic compound with formula (C6H5)3N. In

contrast to most amines, triphenylamine is nonbasic. Its derivatives have

useful properties in electrical conductivity and electroluminescence, and

they are used in OLEDs as hole-transporters

Ultraviolet (UV) light-induced

keratoconjunctivitis

The symptoms first appear within hours after UV exposure and vary from a slight

irritation to severe sloughing of the epithelium with intense pain and tearing

UV light is absorbed in the cornea and the lens, with only minimal amounts

reaching the retina in normal eyes. Regular plastic lens materials absorb UV light.

UV burns of the cornea should be treated with sterile ointment, tight bandaging

and pain medication

subacute damage may also occur from lower levels of exposure to UV light.

Symptoms include dryness or foreign-body sensation in the late night and early

morning hours. Chronic exposure may lead to thickening of the conjunctiva and

changes in the corneal surface.

Disorders of the lens

correlation between a high level of exposure to UV-B light and

cortical and posterior subcapsular cataracts

most eyeglass materials effectively absorb UV light, workers who

wear regular glasses are less exposed to environmental UV radiation

outside their working hours than are those who do not use spectacles

or sunglasses

Exposure to organic nitrate explosives has been reported to be

associated with cataract formation

prevalence of cataracts was noted in glass and metal workers, felt to

be related to short-wave infrared radiation

Disorders of the retina and optic pathways

Light-induced retinal damage can occur from

phototoxicity or thermal injury .The former is typically

caused by short-wavelength light, the latter by visible and

infrared light.

Blue light seems to have particularly unfavorable effects

on the elderly retina

Exposure to lasers can cause serious, permanent loss of

central vision

Laser burns

Grade 1, retinal edema;

Grade 2, retinal coagulation necrosis;

Grade 3, necrosis with hemorrhage;

and Grade 4, hemorrhage bursts into the vitreous

Extended exposure to very low-level laser energy may

cause subtle damage to the retina; this has been reported in

ophthalmologic surgeons who perform laser coagulations

regularly over a period of several years.

A number of solvents have been reported to cause altered color

vision, most commonly in the blue–yellow axis

chronic exposure to styrene, toluene, perchloroethylene, n-hexane,

carbon disulfide and solvent mixtures.

Carbon disulfide has also been reported to cause changes in the

retinal capillary bed resembling diabetic retinopathy

Eye strain and visual ergonomics

Symptoms of eyestrain include sore eyes, headaches, and fatigue, often associated

with intensive close work, including reading and use of video display terminals

Poor contrast or small text may force workers to function too close to their visual

threshold

If the direction of gaze is too high, blinking decreases, and dry spots appear now

and then on the cornea, causing discomfort

Poor placement of a video display terminal may cause glare from a window or

artificial lighting

When visual targets are placed lower, not only is the head posture better, but also

eye irritation becomes less common as the lid aperture becomes smaller, blinking

more frequent, and thus the tear layer on the cornea more stable

Accidents

The CDC indicates that eye injuries are a leading cause of

work-related diseases and injuries in the United States

Between 5% and 19% of all industrial accidents involve

eye injuries 84% of which were considered minor

only 1.5% were wearing safety glasses

Superficial foreign bodies

Superficial foreign bodies are the most commonly

occurring work-related eye injuries.

After it is removed, antibiotic ointment is applied. Corneal

abrasions usually heal within 48 hours but it is wise to use

ointment nightly for a week

Complications of corneal abrasions include infection and

recurrent erosions

Penetrating ocular foreign bodies

If a penetrating injury is suspected, the eye should

be covered with a sterile patch when the patient is

sent to the emergency clinic

21% occurred at the workplace,

fewer than 10% of the injured were wearing

eyeglasses or goggles,

and only 1.5% were wearing safety glasses

Chemical injuries

strong acids and bases

Immediate irrigation is essential to minimize permanent vision loss

Irrigation is continued while transporting the patient to an emergency room for further treatment

protective eyewear should always be worn when handling corrosive or caustic fluids and gases, preferably behind a protecting window or screen

Electromagnetic radiation

Visible and ultraviolet wavelengths have been associated

with pterygium and macular degeneration

Infrared exposure in glass and metal workers has been

associated with cataract formation

Microwaves may be associated with cataract formation

Workers should have an eye examination and

photographic documentation of any eye pathology prior to

working in places where there is risk of exposure to laser

Prevention 60% of workers who suffer eye injuries did not wear eye protection at the

time of the injury; 40% of those who wore protection wore the wrong kind

of protection.

(1) making an assessment of operations and exposures that pose a risk;

(2) checking for visual problems in routine health exams;

(3) reducing exposures by requiring the use of appropriate protective

eyewear, and worksite and engineering modifications;

(4) planning for eye emergencies;

(5) reviewing written procedures and strategies for preventing and dealing

with eye injuries

neurotoxic chemicals in the environment should be known and carefully

avoided in the workplace