What Is Diabetic Retinopathy?

Diabetes is a condition which affects the body’s ability to use and store sugar.  Incidence of the disease is reaching epidemic proportions in our country—increasing six-fold in the last 30 years.  Medical achievements have enabled those suffering from diabetes to better control their disease.  However, as the lifespan of diabetics has increased, so has the incidence of related circulatory problems that can develop over time, including the sight-robbing complication known as diabetic retinopathy—a leading cause of blindness in Americans under age 65. 

Diabetic retinopathy is a complex disorder most likely triggered by a variety of biochemical, metabolic and hematologic (blood-related) abnormalities brought on by diabetes.  These abnormalities cause the deterioration of the small blood vessels, which nourish the retina, the thin layer of nerve tissue in the back of the eye.  These weakened vessels may begin to leak fluid or bleed, thus damaging the retina and blurring the images sent to the brain.

All diabetics (Type I or II, insulin-dependent or not) are at risk.  And, the incidence and severity of retinopathy increases with the number of years you have diabetes.  Patients with diabetes for less than five years have a 15 percent incidence of retinopathy.  This increases to about 70 percent in those who are diabetic for at least 10 years, and to 90 percent after 20 years.  Medical factors, including blood sugar control, high blood pressure, cholesterol level and smoking also affect the degree of retinopathy. 

In addition, diabetes doubles the risk for developing cataracts and glaucoma.

   Background Diabetic Retinopathy

Background diabetic retinopathy results from leakage of the small retinal blood vessels.  These capillaries may either become occluded (blocked) or dilated (swollen), leading to the development of microaneurysms (tiny swollen sacs in the vessels).  Diabetic blood vessels and microaneurysms often leak fluid, blood and fatty materials into the retina.  This leakage can make the retina wet, swollen, and unable to function properly.

When swelling occurs in the central part of the retina (the macula), it is known as “macular edema.”  The macula is the small, highly specialized center of the retina that is responsible for “straight-ahead” vision.  Macular edema usually affects both eyes, but not necessarily to the same degree.  Typically, there is no pain or redness, and symptoms include blurred or distorted vision of varying extent.  Only when deposits or fluid involve the macular area is decreased vision actually noted.  Thus, some patients with significant background diabetic retinopathy may still have excellent vision if the macula is spared.

Background diabetic retinopathy is the most common form of the disease, accounting for 80 to 90 percent of all cases.  Although it rarely leads to total blindness, 5 to 20 percent of patients with the condition may become legally blind (20/200 or less vision) within five years.

   Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy is the most severe vision-related 
complication of diabetes, often leading to blindness if left untreated.  
It develops in 10 to 15 percent of diabetics.

Proliferative diabetic retinopathy begins in the same manner as background retinopathy but is then marked by the growth (“proliferation”) of new blood vessels (“neovascularization”) on the surface of the retina or optic nerve head.  To further explain, with proliferative retinopathy, the retina is unable to obtain valuable nutrients needed for the vision process.  To compensate, new blood vessels grow.  Unfortunately, however, these vessels are very fragile and may end up further damaging the eye by causing other problems that can lead to permanent loss of vision and even loss of the eye, including:

• Vitreous Hemorrhage:  With this, the fragile new vessels rupture and bleed into the vitreous, the clear, jelly-like fluid which fills the center of the eye.  Symptoms to watch for include fairly sudden loss or blurring of vision and seeing numerous floating spots (resembling spider webs) or a dense veil or dark spots. 

• Retinal Detachment:  Although vitreous bleeding usually clears with time, it can (especially with repeated hemorrhages) create scar tissue.  This scar tissue may tighten and pull on the retina, causing it to detach from the back of the eye.  Symptoms include sudden onset of floaters or a cobweb or curtain effect. Retinal detachment may result in severe vision loss or even blindness.

• Rubeosis:  Growth of abnormal new blood vessels on the iris (the colored part of the eye), rather than the retina, that can lead to the following problem.   

• Neovascular Glaucoma:  Rubeosis vessels on the iris can block the natural flow of fluid out of the eye.  This increases pressure in the eye, leading to a severe form of glaucoma (“neovascular”) that can result in permanent vision loss.

Proliferative diabetic retinopathy can occur in adult-onset diabetics, but it is more likely to develop in juvenile-onset diabetics, affecting almost 60 percent of those patients with more than 30 years of insulin-dependence.  Over a five-year period, 50 percent of patients with the condition will become legally blind if they do not have laser treatment.  Thus, it is especially important to detect this more severe form of diabetic retinopathy early. 

For most people with proliferative retinopathy, however, there are no early symptoms.  There is no pain, blurriness or inflammation.  Patients may have good (or near normal) vision until the onset of vitreous hemorrhage or another serious problem causes symptoms.  Others may, however, notice a change in their central and/or color vision as a result of macular edema (the leaking of blood vessels onto the central retina, or macula).  This can often be treated if detected early. 

Diabetic eye disease is detected through comprehensive eye examinations involving dilation of the pupil (enlarging with drops) to best see into the back of the eye.  The following methods may be used to diagnose and monitor diabetic retinopathy.

Ophthalmoscopy:  An instrument called an ophthalmoscope is used to check for early signs of retinopathy, such as microaneurysms (tiny blister-like outcroppings on retinal blood vessels that can bulge and leak), before noticeable vision loss occurs. 

Fluorescein Angiography:  During this in-office test, fluorescein dye is injected into the patient’s arm vein.  After this dye circulates throughout the body to the blood vessels inside the eye, a special camera takes a rapid series of pictures.  (The retina is the only part of the body where blood vessels can be seen directly.)  Normal retinal vessels won’t leak the dye.  Abnormal small diabetic retinal vessels and neovascular (new) vessels, however, may leak the dye and can be captured on film.  As a result, fluorescein angiography can aid in the diagnosis and classification of diabetic retinopathy.  It can also be used as a valuable “roadmap” when laser treatment of leaky blood vessels is indicated.

Ultrasonic Testing:  In cases where bleeding obscures viewing of the retina, ultrasonic testing can be useful to ensure that bleeding and scar tissue has not caused a retinal detachment.

Optical Coherence Tomography (OCT):  Eye Care Specialists is pleased to join prestigious eye institutions and research centers across the country in offering the newest advancement in diabetic retinopathy diagnosis and tracking—Optical Coherence Tomography (OCT).  During this fast, painless procedure, patients simply focus on a light while a safe, invisible laser scans the back of the eye to acquire an image in just seconds.  The OCT then creates detailed computer printouts that provide unparalleled accuracy in visualizing and measuring the severity and extent of swelling present from diabetic retinopathy (referred to as “macular edema”).  During follow-up OCTs, any swelling of the retina can be promptly detected and treated to help prevent vision loss.  After laser treatment, OCTs are used to assess response to therapy. 

OCT testing is also an advancement in glaucoma diagnosis and treatment because optic nerve changes can often be detected sooner and easier than by traditional visual inspection or air puff pressure and visual field tests.  This is important for people with diabetes, since they are twice as likely to develop glaucoma.

In addition to undergoing the above tests, it is important that you provide your doctor with an accurate medical history, including any vision concerns or symptoms, hereditary problems, and medications used. 

It is vital to understand that significant retinopathy may be present before noticeable vision loss occurs (if the macula is spared).  Early detection and treatment are crucial to reducing the risk of vision loss from diabetes.  As such, all diabetics should:

1. Schedule yearly dilated eye exams (more often, if recommended).

2. Call your eye care specialist immediately if you notice a vision change (not associated with blood sugar fluctuations), floating spots (like spider webs), or a “veil” over your vision. 

3. Schedule an eye exam if you become pregnant, since this can speed the progression of retinopathy.

At present, diabetic retinopathy can NOT be prevented or cured.  Fortunately, however, prompt diagnosis, diligent monitoring and timely treatment can control the sight-robbing effects of diabetes.  The following steps are used to stave off vision loss.

   Medical & Lifestyle

Blood Sugar Control:  Besides being important for your general health, good long-term control of diabetes through medication, diet and exercise may also greatly reduce your risk of vision loss.  Studies have shown: 

• In diabetics with no eye disease, excellent blood sugar control 
  reduced the risk for later development of retinopathy by 76%.

• In patients with mild retinopathy, excellent blood sugar control 
  slowed its progression by 54% and reduced the development 
  of severe diabetic retinopathy by 47%.

Healthy Lifestyle:  Proper diet and exercise are crucial to anyone’s good health, especially people with diabetes.  Also, controlling blood pressure and not smoking definitely decrease the complications of diabetes, including retinopathy.

Regular Check-Ups:  See your doctor, endocrinologist and eye specialist as often as recommended.  Surprisingly, a study found that one-third of people who know they have diabetes do not adhere to guidelines for yearly dilated eye exams.  Why should you go, especially if your blood sugar has always been under control?  You need your eyes checked because diabetes is also a disease of the tiny blood vessels, especially the capillaries, and retinopathy may progress independent of blood sugar levels.  Duration of the disease process is really the most critical factor in determining the development and extent of retinopathy.

   Laser Treatment

Laser therapy is the mainstay of treatment for both types of retinopathy.  Although not all diabetics can have or need laser treatment, it has proven very effective in reducing the incidence of severe visual loss, especially if begun early enough.  Its main goal, however, is to stabilize the retinopathy—not to restore lost vision.  Deciding when or whether to use laser therapy depends on the type of retinopathy, location, severity, and your doctor’s opinion as to how well the condition may respond to treatment.

Treatment is performed in our office or outpatient surgery center.  Topical (drops) or local (injection) anesthesia is used.  During laser photocoagulation, a high-energy beam of light of a specific wavelength is sharply focused onto specific areas of the retina.  This light turns to heat and seals leaking blood vessels (for background retinopathy) or helps prevent the growth of abnormal new blood vessels (for proliferative retinopathy). 

W  Background Diabetic Retinopathy

The immediate goal of laser photocoagulation in background diabetic retinopathy is to seal individual leaking vessels, thus hopefully halting further vision loss.  However, since the laser only seals current leaks, it is common to require repeat laser treatment as other vessels begin to leak in the future.

There are two types of laser treatment used for background diabetic retinopathy:  “focal” and “grid.”  With focal treatment, the laser targets specific areas of leakage pinpointed by fluorescein angiography testing.  In some patients, however, the leakage into the retina is widespread and diffuse, rather than from a few specific leaking blood vessels.  For these cases, the laser is used to make a grid pattern across the entire leaking (“wet”) area.  Patients can sometimes see the small spots where focal or grid treatment was done, but this rarely poses a problem.

A study of laser treatment for background retinopathy showed that early use for macular edema (fluid in the macula) decreased the incidence of marked vision loss by 50 percent.  In some cases, however, leakage is so far advanced before the laser is used that success is much less likely.  Thus, patients must realize that laser therapy is not always successful and that preservation of current vision, not improvement, is the primary goal.

W  Proliferative Diabetic Retinopathy

With proliferative diabetic retinopathy, laser photocoagulation aims to prevent further new vessel development and to shrink existing vessels (or, ideally, make them disappear completely).  This then decreases the chance of hemorrhaging and subsequent loss of vision.

Proliferative treatment is commonly done over a period of two to four sessions per eye and involves placing 1,000 to 3,000 separate tiny laser burns in the outer area (periphery) of the retina.

National studies have long proven the usefulness of this course of therapy, showing about a 60 percent reduced incidence of severe vision loss with appropriate and timely treatment.  But, there still is no guarantee for success, especially if laser therapy is not started until late in the course of retinopathy.

The most common side effects of laser therapy include an occasional slight decrease in central and/or night vision, and a restriction in peripheral (side) vision.  However, these are rarely a major problem and are a small price to pay for the significantly increased chance of retaining vision through laser treatment.

   Surgical Treatment

If laser photocoagulation is impossible or unsuccessful in preventing recurrent vitreous hemorrhage, scar formation or retinal detachment, an operation known as a vitrectomy may be performed.  
This is a major surgical procedure in which the bloody fluid and abnormal scar tissue in the vitreous cavity are removed and replaced with a clear, artificial solution.  Although complications may occur, about two-thirds of patients have some vision improvement with this technique.

   Ocular Steroid Injection

With this newer, painless procedure, a long-acting anti-inflammation medicine (steroid) is injected in or around the eye to try to reduce diabetic retinopathy swelling.  Ocular steroid injection holds great promise for qualified candidates.

1. Control your diabetes.  Fluctuations in blood sugar levels can temporarily affect vision, 
   making it more difficult to detect serious problems.  Good control slows the onset and 
   progression of retinopathy and lessens the need for laser surgery.

2. Schedule yearly dilated eye exams. 
   Advances in diagnosis and treatment are of no value if you don’t utilize them. 

3. Be an informed partner.  Ask your primary care doctor, endocrinologist and eye specialist 
   for the latest updates.  Read.  Research.  Your vision is priceless.  Treat it that way.

Scientists are beginning to understand the changes that cause vessels to leak in background diabetic retinopathy and have begun to isolate the chemical messenger that causes new blood vessels to grow (neovascularization) in proliferative retinopathy.  Such research aims to produce drugs or treatment methods that could prevent blood vessel leakage or neovascularization from ever occurring.  Furthermore, new instruments and techniques are being studied and introduced to improve the success rate of surgery for vitreous hemorrhage and diabetic retinal detachment.

Blindness due to diabetes takes a terrible toll on patients, their loved ones and society in terms of quality of life and financial burden.  Although, at present, we cannot prevent or cure diabetic retinopathy, early detection, careful tracking, and timely treatment can often decrease the risk of severe visual loss.  Those are steps worth taking to gain every opportunity to see life to the fullest.

If you would like a detailed color booklet with the information contained in this section and/or to schedule a comprehensive evaluation for diabetic eye disease, please feel free to contact Eye Care Specialists’ Communications & Education Department at 414-321-7035.