Published in "Panorama"
Diabetes & the Eye
Patients with diabetes are more likely to develop eye problems such as cataract and glaucoma but the most common and serious eye complication of diabetes, which could be vision-threatening, is diabetic retinopathy, says Dr.Saleem Moopen, Specialist Ophthalmologist, Dr.Moopen’s Polyclinic, Deira.
Diabetes increases the risk of cataracts, a condition in which the lens of the eye becomes cloudy. Also, people with diabetes tend to get cataracts earlier than people without the disease. A severe form of glaucoma, a disorder in which the pressure inside the eye is increased, is also linked to diabetes.
Diabetic retinopathy is a condition where there is damage to the retina which is the light-sensing area in the back of the eye. It usually occurs in both eyes though the condition may be at different stages in the two eyes. Explaining the condition, Dr.Moopen states, “Diabetic Retinopathy occurs when diabetes damages the tiny blood vessels in the retina. The condition develops through different stages. In non-proliferative retinopathy, or background diabetic retinopathy, these blood vessels leak fluid and distort sight.
Background diabetic retinopathy itself does not usually damage the vision, but it signals that all is not well with the body’s vascular system and specifically of the eye. In many people with diabetic retinopathy, the disease remains mild and doesn’t cause visual problems. However, a complication of background diabetic retinopathy, and also of more severe forms of diabetic retinopathy, is diabetic macular edema, a swelling of the retina. “But in some people, a continuous leakage from the retinal blood vessels may lead to macular edema which is a build-up of fluid in the macula, the part of the retina responsible for the sharp, clear vision used in reading, driving and other such activities. When critical areas of the macula swell up with excess fluid, the patient complains of blurred vision and may find difficulty in reading, driving, et al.”
Some people with diabetes develop an even more vision-threatening condition called proliferative retinopathy, reveals Dr.Moopen. “While this may occur in people with macular edema, it can also develop in those without it. In proliferative retinopathy, new and abnormal blood vessels grow on the surface of the retina. These vessels are fragile and can rupture and bleed into the middle of the eye, blocking vision. Scar tissue may also form near the retina and this may also cause the retina to detach from the back of the eye. Severe visual loss and even permanent blindness can result from this, though this happens in a very small percentage of people.”
What are the risk factors of diabetic retinopathy? Who is at risk of developing this disorder?
1. Anyone with diabetes (Type I or Type 2) is at risk of developing retinopathy, though not every diabetic need develop the condition. About 50-55% of diabetics get the condition. Of these, only 3% get vision-threatening complications.
2. The duration for which an individual has been having diabetes is another important risk factor, risk increasing in direct proportion to the length of time for which the patient has been having diabetes. Usually after 10-15 years of diabetes, 75% of people show some signs of diabetic retinopathy.
3. Diabetic Retinopathy is uncommon before puberty, even if a child is diabetic or has juvenile diabetes.
4. Diabetes Complications and Control Trial (DCCT) study, a very reputed study in the field has proved that good control of diabetes prevents diabetic retinopathy. Prior to this study, it was believed that Diabetic Retinopathy is not preventable. However, the good news, as proved by the DCCT study is that, the condition is preventable.
5. Systemic Hypertension co-existing with diabetes, increases the risk of diabetic retinopathy.
6. Pregnancy in diabetic women can lead to the progression of diabetic retinopathy. This does not refer to cases of gestational diabetes, but of individuals who already have diabetes and become pregnant. These patients who already have a slight diabetic retinopathy, have the condition progress faster when they become pregnant.
The important factor to be considered is that Diabetic Retinopathy may be totally symptomless for a long period of time, says Dr.Moopen. Occasionally, patients may complain of floaters – of something floating in front of their eyes. In background diabetic retinopathy, there are no symptoms. If macular edema develops, the patient may complain of blurred vision. But when it is proliferative diabetic retinopathy, the symptoms manifest suddenly as loss of vision, when the vessels bleed and the blood blocks the vision.”
How is Diabetic Retinopathy diagnosed?
A thorough eye examination by an eye specialist is important. Initially a plain fundus examination is done to detect early stages of the condition wherein the pupils are dilated and examined. Dr.Moopen explains, “This is the basic examination through which we can detect most of the Background Diabetic Retinopathy. However, where the clinical diagnosis significantly reveal macular edema, and also where we suspect there are some new vessels, diagnosis to confirm the conditions involve doing a Fluorescein Angiogram. The fluorescein dye, pigmented dye is injected into an arm vein and photographed as it passes through the retinal blood vessels. This helps to determine the source and extent of fluid leakage.
Is the sudden loss of vision reversible with prompt medical attention?
The sudden loss of vision is due to the advanced case of diabetes. So the question of reversing diabetic retinopathy is not possible, emphasizes Dr. Moopen. “Whatever damage has been done, cannot be reversed. But by detecting the condition early, vitrectomy, surgery for removing the clot, can help to save some amount of vision in the person. So it is better to prevent diabetic retinopathy than treat it. Laser photocoagulation is done to prevent further progression of the disease, not to cure the condition. However, I repeat, that the best treatment for diabetic retinopathy is the prevention of diabetes and control of diabetes when it has occurred.”
What are the risks of photocoagulation? In the first instance, before doing laser photocoagulation, a fluorscein angiogram is done to identify the exact vessel to burn. Dr.Moopen is forthright in labeling photocoagulation itself as a destructive procedure in that it can cause night blindness. “The process itself can cause retinal detachment as a complication. But normally, such complications from the procedure are very rare. However, even after photocoagulation, if the patient does not maintain strict control over his diabetes, eye complications can occur.”
How does one prevent Diabetic Retinopathy? All people with diabetes should take precautions to help reduce their risk of developing eye problems, emphasizes Dr.Moopen.
1. People with background diabetic retinopathy should be examined once every 6 months.
2. Schedule regular appointments with your eye doctor so that any eye problem can be detected early and treated.
3. Maintain control of your blood glucose level.
4. Keep blood pressure under control. High blood pressure by itself can lead to eye disease, so if you have hypertension along with diabetes, it is especially important that you take measures to control both.
5. Eat a healthy diet.
6. Avoid Smoking
7. Exercise regularly.