Keep Your Eyes on the Future

7/31/2019 Keep Your Eyes on the Future

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KEEP YOUR EYES ON THE FUTURE!Dr. S.M.Sadikot.Hon. Endocrinologist,Jaslok Hospital and Research Centre,Mumbai 400026

Look at the picture below on the left hand side. This is what you would see if you were walking alongthe road. Now look at the picture on the right. This is what you would see if your eyes are affectedwith severe diabetic retinopathy!

Terrible, is it not?

Normal Vision Vision affected by diabetic retinopathy

This is in no way meant to frighten you. But you must realize that unless you are careful aboutmanaging your diabetes, this could happen to you.

If you have diabetes this does not necessarily mean that your sight will be affected, but there is ahigher risk. If your diabetes is well controlled then you are less likely to have problems, or they mayremain at a mild level.

Although giant strides have been made in the treatment of diabetic retinopathy, the best treatmentstill remains "prevention" and even if one cannot completely avoid getting the retinal complications,


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one can definitely slow down its progression, so that it never reaches a level serious enough to cause"blindness"!

But a large part in saving your eyes lies in your hands!

Before, we discuss these aspects, let us first understand what is diabetic retinopathy.

Diabetic retinopathy is a general term for all disorders of the retina caused by diabetes. This iscommonest complication of diabetes to do with the eyes. It is a progressive disease that destroyscapillaries (the smallest blood vessels linking arteries to veins) in the eye by depositing an abnormalmaterial along the walls of the tiny blood vessels in the retina. Blurred vision and often blindnessfollow.

How can diabetes affect the eye?

Your eye has a lens and an aperture (opening) at the front, which adjust to bring objects into focus onthe retina at the back of the eye. The retina is made up of a delicate tissue that is sensitive to light,rather like the film in a camera.

At the centre of the retina is the macula which is a small area about the size of a pinhead. This is themost highly specialised part of the retina and it is vital because it enables you to see fine detail andread small print. The other parts of the retina give you side vision (peripheral vision). Filling the cavityof the eye in front of the retina is a clear jelly-like substance called the vitreous.

The retina is a light-sensitive tissue at the back of the eye. When light enters the eye, the retinachanges the light into nerve signals. The retina then sends these signals along the optic nerve to thebrain. Without a retina, the eye cannot communicate with the brain, making vision impossible.

To view an interactive lesson in the functions of the various parts of the eye,click here

How does the eye "see"?

Thinking of a camera can help you understand how the eye works. macular or retinal damage.
http://www.diabetesindia.com/diabetes/process/eye.htmhttp://www.diabetesindia.com/diabetes/process/eye.htm


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The lens of the camera in yellow,

the film in blue The lens of the eye in yellow,the retina in blue

A camera lens focuses a picture onto a film inside the camera. In our eyes the same thing happens,but the film is replaced by the retina. The retina 'makes' the pictures of the world that we see,converting the light into electrical signals that are then sent on to the brain.

The eye as a camera. Above, the image of thehouse focusing on the retina. The central part of any image, a house or a person's face for instance, will be clear if the maculais healthy.

The retinal cells stand next to each other, a bit like houses in a street. The main cells are the rods andcones: these are the cells that take up light and convert it into electrical messages, which are then

sent onto the brain.

These cells receive their oxygen and other nutrients from tiny blood vessels nearby. These bloodvessels are like pipes which pass nearby the cells; imagine a largish pipe passing past your house,containing blood. The walls of these pipes/blood vessels are very thin, and so nutrients can passthrough them. These nutrients are the 'food' for the cells.


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Light ...in yellow... falls onto the retina. The retinal cells are rods (the long straight cells) and cones (the cells with thepointed end). There are tiny blood vessels (capillaries) on the surface of the retina ...the red ovals.

As you read on, you will understand the major role played by a part of the retina called the "macula"

The macula is the most sensitive part of the retina. It makes out the fine details of the things we lookat, peoples' faces, bus numbers, reading and writing, and everything lese we see.

If the macula is damaged all these things you see in fine detail are misty. The picture is still there butyou cannot make out any of the detail.

A healthy retina will produce a clear image, like a normal film in a camera. But in macular damage the

image will not be clear.

For example if the film was scratched in the middle, the 'scratch' would show up in the middle of thephotograph like a black mark or blot of ink. This is similar to damage caused by macular disease suchas diabetic maculopathy.

Everything will appear blurred of the macular area of retinais damaged. This shows the importance of the "macula".

Diabetes causes damage to the blood vessels that nourish the retina, the seeing part at theback of the eye.


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What is Diabetic Retinopathy?There are two types of diabetic retinopathy, non-proliferative or proliferative.

Nonproliferative retinopathy is the common, mild form. It accounts for about 80 percentof all cases.It usually has no effect on vision and needs no treatment. But after it isdiagnosed, have your eyes checked at least yearly to make sure it's not getting worse.

For an excellent interactive look at all these retinal changes from the normal to the mostserious, click here .

In nonproliferative retinopathy, capillaries balloon and form pouches. Although retinopathydoes not usually cause any vision loss at this stage, the retinal vessels weaken and developbulges (microaneurysms) that may leak blood (hemorrhages) or fluid (exudates) into thesurrounding tissue.

A healthy capillary, a tiny blood vessel .Nutrients pass out of the capillary to reach the

retinal cells, and waste products from the retina

pass into it to be taken away.

In diabetic retinopathy the damaged capillaries start to leakfluid.

The ability to control the passage of substances between the blood vessels and the retinamay be lost. As a result, the retina becomes swollen and fatty deposits form within it. If thisswelling affects the center of the retina, the "macula", this called macular edema and visionloss can result, as we have seen above.

Your doctor must have either sent examined the inside of your eyes or sent you to an "eye"specialist to have a fundus examination. This is nothing but examining the retina in your eyewith the help of an instrument called the "ophthalmoscope" .

This is how the retina appear to the doctor if your eyes have not been affected by diabetes.
http://www.diabetesindia.com/diabetes/process/dmret.htmlhttp://www.diabetesindia.com/diabetes/process/dmret.html


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A Normal eye

In order to understand this more clearly, this is a schematic view of a normal eye

When you have non proliferative, (or "background") retinopathy, this is what the doctorwould see.

The small red dots are 'microaneurysms', tiny damaged capillaries. The red lines are small haemorrhages, littleflecks of blood.

The number of microaneurysms, the little red dots the doctor sees, indicate the likelihood of


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more severe problems in the years to come.

If you are not careful in some people, retinopathy progresses to a more serious form calledproliferative retinopathy.

Initially, there is a stage which has been variously thought of as being a late nonproliferative stage or as an early proliferative stage.

For an excellent interactive look at all these retinal changes from the normal to the mostserious, click here .

Let us call it a prepropliferative stage.

In this stage the retina has been damaged by the higher than normal sugar levels overseveral years. Small haemorrhages (flecks of blood) and tiny abnormal blood vessels are

present.

If this progresses and many new vessels start developing in the retina, one has progressedto the proliferative stage.

The blood vessels can make a special growth chemical (VEGF= vascular endothelial growthfactor) that makes other tiny, tiny blood vessels grow. These are called 'new' bloodvessels.These new vessels are very delicate and very easily bleed, and this blood can (if theeye is not lasered) damage your eye badly.


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The damaged capillaries start to make a special growth chemical that makes other capillaries grow.

If the blood vessels are severely damaged, they close off. In response again, new bloodvessels start growing in the retina.

The capillaries start to close up and block. Theretinal cells nearby can become damaged, and

the sight reduced.New blood vessels growing on the retinal surface and slightly in

front of the surface

This is ' proliferative retinopathy'.

Usually in this condition, without laser treatment ( see below), the sight is very badlyaffected and people may become blind.

laser: 1000 burns in a typical session Usually inthis condition, without laser treatment, thesight is very badly affected and people may

become blind.

proliferative retinopathy 'new blood vessels' grow on thesurface of the retina and can bleed. This process is shown in the

animation (exaggerated).

These new vessels are weak and can leak blood, blocking vision, which is a condition calledvitreous hemorrhage. The new blood vessels can also cause scar tissue to grow. After thescar tissue shrinks, it can distort the retina or pull it out of place -- this is called retinaldetachment.

If the macula is involved, this is a very serious matter. We have seen above that when themacula is involved, the central vision is affected!But this can still be treated in its early stages with laser therapy.


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An excellent composite view of the changes which take place in the vessels as retinopathyprogresses is given below.

For an excellent interactive look at all these retinal changes from the normal to the mostserious, click here.

Why are regular checkups so important?

You must always remember that your retina can be badly damaged before you notice anychange in vision. Most people with nonproliferative retinopathy have no symptoms. Evenwith proliferative retinopathy, the more dangerous form, people sometimes have nosymptoms until it is too late to treat them.

And yet, retinopathy is easily diagnosed through an ophthalmoscopic examination. If yourdoctor sees any evidence of retinal changes, he may then ask you to undergo more tests so


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that he can treat the problems and prevent further progression to a severe state whenvision is seriously affected. There is also some evidence that if diagnosed at an early stage,some of the damage can even be reversible!

For this reason, you MUST have your eyes examined regularly.

Who is most likely to get diabetic retinopathy?

Anyone with diabetes. The longer someone has diabetes, the more likely he or she will getdiabetic retinopathy. Nearly half of all people with diabetes will develop some degree of diabetic retinopathy during their lifetime.

Several factors influence whether you get retinopathy. These include your blood sugarcontrol, your blood pressure levels, how long you have had diabetes, and your genes.

The longer you've had diabetes, the more likely you are to have retinopathy. Almosteveryone with Type 1 diabetes will eventually have nonproliferative retinopathy. And mostpeople with Type 2 diabetes will also get it. But the retinopathy that destroys vision,proliferative retinopathy, is far less common.

What can be done to prevent serious eye problems?

There are steps you can take to avoid eye problems.

First and most important, keep your blood sugar levels under good control.

Many studies have shown the importance of a good control of your blood glucose levels. If you do not have diabetic retinopathy and do NOT keep your diabetes under control, yourhave FOUR times the chances of getting retinopathy as compared to someone who doeskeep his diabetes well controlled!

In people who already had retinopathy, the condition progresses in those with good controlonly half as often as those not well controlled.

In fact, it has been shown that for each 1% rise in the HbA1c, ( we have discussed HBA1c or

glycoisylated hemoglobin in the section on monitoring control) the retinopathy gets worse atthe rate of 32%. So if your HbA1c is 9%, your retina is getting damaged twice as fast assomeone with a level of 6% (3 x 32% = 92% additional deterioration).

High blood pressure is fairly common in people with diabetes. Again you should aim for agood control of your blood pressure 130/80 or less [lower still if there is protein in yoururine]). With blood pressure, for each 10mmHg rise, the retinopathy gets 11% worse. So if your blood pressure is 150/90, your retina is getting 22% worse that someone whose


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pressure is 130/80.

Similarly Smoking literally doubles the rate of damage that diabetes causes to the bodieslarger arteries, making amputations and heart disease far more likely. Smoking triples therate of retinopathy progression

These impressive results show that you have a lot of control over what happens to youreyes!

To sum up,

lifestyle

30-60 minutes exercise a day, moderate alcohol consumption only, avoidobesity if possible, balanced diet including 5 portions of vegetables or fruita day, with the minimal of animal or 'hard' vegetable fats, and very lowsalt.

bloodpressure

130/80 or less125/75 or less if protein in urine present

HbA1c6.5% or less with very few or preferably no hypos.If hypos develop, seeexpert advice.ACE inhibitors or AT11 unless young/pregnant/very lowblood pressure/poorly tolerated

cholesterol


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you have trouble reading signs or books you see double one or both of your eyes hurt your eyes get red and stay that way you feel pressure in your eye you see spots or floaters

straight lines do not look straight

you can't see things at the side as you used toBut as we said above, there are no signs or symptoms in the early stages of the disease.Vision may not change until the disease becomes severe. Nor is there any pain.

Even in more advanced cases, the disease may progress a long way without symptoms.

But to protect your vision, comprehensive eye exams are needed every year, or as directedby your physician. Remember, the most dangerous threats to vision in diabetes give little orno warning. Only by direct examination with an ophthalmoscope can these early changes beseen and treatment started before sight becomes seriously threatened.

That is why regular eye examinations for people with diabetes are so important.


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Although there are quite a few tests which your doctor may carry out, the most importantfrom the viewpoint of diabetic retinopathy detection is an ophthlmoscopic examination of theretina.

Your doctor will use an ophthalmoscope and look at your retina for early signs of thedisease, such as:(1) leaking blood vessels,(2) retinal swelling, such as macular edema,(3) pale, fatty deposits on the retina--signs of leaking blood vessels,(4) damaged nerve tissue, and(5) any changes in the blood vessels.

During this examination, your doctor may put in some eye drops to dilate your pupils so thathe gets a better view of the retina and also to prevent the pupil from contracting when thelight from the opthalmoscope falls on the retina. Your vision may be blurred for a few hours

after this examination and therefore, please take someone with you when you go for thisexamination and definitely do not drive to your doctor's clinic!

Your doctor may ask that you have a test called fluorescein angiography.

Fluorescein angiogram (FA)

Fluorescein angiography is an extremely valuable test that provides information about thecirculatory system and the condition of the back of the eye. FAs are useful for evaluatingmany eye diseases that affect the retina.

Retinal photograph of a patient complaining of decreased vision.

Fluorescein angiogram indicating fluid leakage within the retina


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The test is performed by injecting a special dye, called fluorescein, into a vein in the arm. In just seconds, the dye travels to the blood vessels inside the eye. A camera equipped withspecial filters that highlight the dye is used to photograph the fluorescein as it circulatesthough the blood vessels in the back of the eye. If there are any circulation problems,swelling, leaking or abnormal blood vessels, the dye and its patterns will reveal these in the

photographs. The doctor can then make a determination as to the diagnosis, and possibletreatments.

How is it treated?

There are two treatments for diabetic retinopathy. They are very effective in reducing visionloss from this disease. In fact, even people with advanced retinopathy have a 90 percentchance of keeping their vision when they get treatment before the retina is severelydamaged.

This again shows the importance of regular eye checkups!

These two treatments are laser surgery and vitrectomy. It is important to note that althoughthese treatments are very successful, they do not cure diabetic retinopathy.

Laser Surgery

Laser surgery is performed in a doctor's office or eye clinic. Before the surgery, your ophthalmologistwill: (1) dilate your pupil and (2) apply drops to numb the eye. In some cases, the doctor also maynumb the area behind the eye to prevent any discomfort.

The lights in the office will be dim. As you sit facing the laser machine, your doctor will hold a speciallens to your eye. During the procedure, you may see flashes of light. These flashes may eventuallycreate a stinging sensation that makes you feel a little uncomfortable.

In laser treatment, the doctor makes tiny burns on the retina with a special laser. These burns seal theblood vessels and stop them from growing and leaking.


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In scatter photocoagulation (also called panretinal photocoagulation), the doctor makes hundreds of burns in a polka-dot pattern on two or more occasions. Scatter photocoagulation reduces the risk of blindness from vitreous hemorrhage or detachment of the retina -- but it only works before bleeding or

detachment has progressed very far.

Side effects of scatter photocoagulation are usually minor. They include several days of blurred visionafter each treatment and possible loss of side (peripheral) vision.

In focal photocoagulation, the eye care professional aims the laser precisely at leaking blood vessels inthe macula. This procedure does not cure blurry vision caused by macular edema. But it does keep itfrom getting worse.

For the rest of the day, your vision will probably be a little blurry. If your eye hurts a bit, your doctorcan suggest a way to control this.


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You may leave the office once the treatment is done, but you will need someone to drive you home.Because your pupils will remain dilated for a few hours, you also should bring a pair of sunglasses.

laser for proliferative retinopathy (white for illustration) a common type of laser for maculopathy (burns are shown white for illustration)

When the retina has already detached or a lot of blood has leaked into the eye, photocoagulation is nolonger useful.

Vitrectomy

The next option is vitrectomy, which is surgery to remove scar tissue and cloudy fluid from inside theeye. The earlier the operation occurs, the more likely it is to be successful. When the goal of theoperation is to remove blood from the eye, it usually works. Reattaching a retina to the eye is much

harder and works in only about half the cases.

How Common Are the Other Diabetic Eye Diseases?

If you have diabetes, you are also at risk for other diabetic eye diseases. Studies showthat you are twice as likely to get a cataract as a person who does not have thedisease. Also, cataracts develop at an earlier age in people with diabetes. Cataracts canusually be treated by surgery.

Glaucoma may also become a problem. A person with diabetes is nearly twice as likelyto get glaucoma as other adults. And, as with diabetic retinopathy, the longer you havehad diabetes, the greater your risk of getting glaucoma. Glaucoma may be treated withmedications, laser, or other forms of surgery.Self-Testing The Eye

At times, someone who has diabetes can detect changes in their vision that warn of problems. These changes can be found using a simple Amsler grid. Testing with anAmsler grid helps to detect vision changes caused by poor control, macular edema, or adetached retina. The grid is used by doctors to detect eye problems, but it only detectsproblems in the macula and cannot check other regions of the eye.

Your doctor may ask you to test yourself with an Amsler's Chart.

Anyone who has been told they have significant eye changes caused by diabetes shouldtest each eye daily. If you notice any changes in your vision, see your eye doctorimmediately.


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Instructions for the test using the Amsler grid:

1. Look at the square (grid).

2. Wear your reading glasses (if you use one) and cover one eye.3. Focus on the center dot for one full minute.4. While looking directly at the center, be sure that all the lines are straight and clear,and all the small squares are the same size.5. Repeat the test in the other eye.6. If any lines or squares appear distorted, wavy, blurred, discolored, or otherwiseabnormal, call your eye doctor right away.7. In healthy eyes the lines are straight.The Amsler's chart is very useful for early detection of macular problems and thus isvery important as this may be an early sign of macular problems and lead to a loss of central vision! But one must know its limitations.The Amsler grid will NOT detectproliferative diabetic retinopathy, most preproliferative changes and other types of damage that may threaten vision, nor is it useful for detecting any of the early changes.Remember: a normal Amsler grid test does not rule out the presence of retinopathythat can threaten your vision.It cannot replace routine eye exams. Only regular eyeexams can do this.

Finally,

You will realize that protecting yourself against serious diabetes eye complications is in yourhands.

Even if one cannot "see" INTO the future, at least one can "see" in the future!!

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