Diabetic Eye Disease
Diabetic Eye Disease
Diabetes, especially after prolonged duration, may produce diabetic retinopathy in some patients. This is a serious and potentially blinding eye condition. Diabetic retinopathy is the number one cause of legal blindness in the country for patients under 64. [PHOTO: Non-Proliferative Diabetic Retinopathy. The small hemorrhages are signs of damaged capillary blood vessels and poor retinal blood flow.]
Diabetes affects the part of the eye called the retina. The retina is nerve tissue that lines the back of the eye. Visual images are formed on the retina much like on the film in a camera. Diabetes damages the retina by affecting its blood vessels. Some vessels become plugged, while others leak fluid. Sometimes, abnormal blood vessels grow along the surface of the retina and into the vitreous (the clear gel that fills the eye). Bleeding into the eye (vitreous hemorrhage) from these newly formed blood vessels and scarring or detachment of the retina are the main ways that diabetes causes severe impairment of vision. Blurring of vision may also be caused by fluid leaking out of the damaged blood vessel, which produces a thickening of the retina, i.e., macular edema. These and other changes are all included in the term diabetic retinopathy.
Regular eye examinations and appropriate laser therapy have been shown to prevent visual loss in many cases. Laser treatment reduces the risk of blindness with certain stages of diabetic retinopathy. [PHOTO: Proliferative Diabetic Retinopathy. This large pre-retinal hemorrhage came from abnormal blood vessels typical of proliferative diabetic retinopathy.]
Diabetic patients should have periodic eye examinations by an ophthalmologist. The following information underscores the importance of routine periodic eye exams:
- Severe diabetic retinopathy occurs more commonly in patients who have had diabetes for a longer period of time (i.e., 10 or 20 years). However, diabetic retinopathy can also occur early.
- The level and quality of diabetic control may not be related to the severity of the retinopathy.
- The severity of the diabetic retinopathy may not be related to the degree of other complications (e.g., kidney, neurological, etc.)
- The exact duration of the diabetes is usually unknown when diabetes is diagnosed in an adult.
- Diabetics have been shown to have a significantly increased incidence of other eye diseases (e.g., cataracts and glaucoma).
- Eye examinations for diabetic retinopathy are performed by experienced ophthalmologists such as retinal specialists, since certain stages of the disease (e.g., early proliferative diabetic retinopathy, i.e., abnormal blood vessels), may be very subtle in their appearance and difficult to diagnose. In addition, special procedures (gonioscopy, contact lens evaluation, iris and fundus fluorescein angiography) may be necessary in some patients.
- THE DIABETIC PATIENT MAY HAVE NORMAL VISION WITH NO SYMPTOMS AND YET HAVE SIGNIFICANT DIABETIC RETINOPATHY (E.G., PROLIFERATIVE DIABETIC RETINOPATHY) WITH IMMINENT DANGER OF BLINDING COMPLICATIONS (E.G., VITREOUS HEMORRHAGE).
In view of this, a patient with diabetes should be seeing their ophthalmologist or retinal specialist annually until retinal changes are noted. The severity of diabetic retinopathy will dictate the need for more frequent examinations.
Diabetic Laser Treatment
Laser treatment (photocoagulation) uses powerful light rays directed into the eye and focused on a tiny spot on the retina. The light produces heat, which destroys abnormal tissue and cauterizes or seals off the abnormal blood vessels. Photocoagulation is usually not painful and is performed in our office as an outpatient procedure.
Patients with severe bleeding into the vitreous or detachment of the retina may require a major eye surgery called vitrectomy.
The diabetic patient should be aware that eye symptoms of blurred or decreased vision, floaters, flashing lights, distorted vision, etc., may indicate serious eye disease. Fluctuating eye vision may indicate changes in blood sugar levels and may require better blood sugar control by the doctor treating your diabetes or may indicate the presence of macular edema.
Diabetic Macular Edema
The retina is the layer of nerve tissue at the back of the eye upon which light is focused. The retina then converts light into signals, which are sent to the brain where vision is perceived. The central portion of the retina is called the macula, and it is this area, which is responsible for our sharpest central (reading) vision. Small blood vessels travel through the retina supplying it with oxygen and removing waste products.
One of the ways in which diabetes may affect vision is by the development of macular edema (accumulation of fluid in the macula). It is present in about 9% of all diabetics. The likelihood of developing macular edema increases as a person has diabetes for a longer period of time. The only symptom is decreased vision, and because there are many other causes of decreased vision in diabetics, an examination by an ophthalmologist is the only way to determine if a particular person has macular edema. [PHOTO: Diabetic Macular Edema. The white material in the center of the photo is a collection of fluid and lipids called exudate. This patient also has proliferative disease.]
Macular edema is caused by fluid leaking from the retinal blood vessels into the surrounding retina, causing it to become swollen and distorted. Occasionally the term cystoid macular edema is used, referring to the small cystic spaces of fluid accumulation. The leakage may occur in two basic patterns, as a "diffuse" generalized leakage from the blood vessels, or from specific "focal" areas. Your ophthalmologist may order a test called a fluorescein angiogram to help determine which of these patterns is present, as well as the amount of the edema.
Treatment of macular edema is possible with laser therapy or medications injected into the eye. A fluorescein angiogram will help your ophthalmologist determine the best way for the treatment to be applied. A nationwide study by the Early Treatment Diabetic Retinopathy Study Research Group demonstrated that laser treatment could help prevent further visual deterioration. In fact, those who did not undergo treatment were twice as likely to have poorer vision three years later than those who did have the treatment.
The main goal of the laser treatment is to prevent further worsening of the vision, not to improve vision. Patients who receive laser therapy for macular edema may experience short-term worsening of vision in the 6 to 12 weeks following treatment before improvement is noted.
Laser therapy does have small risks for potential complications: Vision could be permanently worsened by the laser treatment itself, although this is rare. Vision may continue to worsen despite the therapy, and multiple laser treatments may be necessary. Patients sometimes complain of permanent dark spots or a generalized haze in their vision after treatment.
Many physicians feel that high blood pressure, abnormal kidney function, and other general systemic factors may contribute to the problem of diabetic macular edema. It is therefore important to have the best possible control of blood pressure, kidney function, and levels of sugar when treating macular edema.
Diabetic macular edema and other diabetic retinopathy changes are complex problems that require continued observation and care under the supervision of your ophthalmologist.
For more information on eye conditions, visit http://www.kellogg.umich.edu/patientcare/conditions/index.html
Email or call us today at 303-772-3300 for a diabetic retinopathy consultation.