Diabetes and eye disease

DR MAXWELL ADEYEMI

The diagnosis of diabetes comes with the possibilities of certain complications, one of them an eye disease known as diabetic retinopathy. As the name suggests, retinopathy affects the retina, a thin layer of light-sensitive tissue that lines the back of the eye. It can lead to blindness.

With diabetic retinopathy the blood vessels in the retina become damaged and begin to swell and leak. The vessels may also close down so that blood doesn't pass through. Sometimes, abnormal new blood vessels begin to grow on the retina. All of these changes can affect your vision adversely.

Diabetic retinopathy can occur in both type 1 and type 2 diabetes, as well as gestational diabetes (diabetes occurring during pregnancy). It is the most common cause of irreversible blindness. It occurs in more than half of the people who develop diabetes.

For those with type 1 diabetes, the average age of onset for diabetic retinopathy is five to 14 years, while for those with type 2 diabetes it is ages 40 to 60.

Along with retinopathy, a condition called macular edema can occur. This involves a swelling of the macula, an area near the central part of the retina that has the keenest vision. About half of people with diabetic retinopathy develop macular edema.

Causes

The primary cause of diabetic retinopathy is sustained high blood sugar, which over time can harm the blood vessels in the retina. Diabetes damages the tiny blood vessels that nourish the retina. The condition can sneak up on patients but regular eye exams can detect early changes that might be worrisome. The key, is identifying retinal changes before a patient has vision loss. Glucose control and regular follow-up with a retina specialist is essential.

Risk factors

Besides high blood sugar, several factors increase the risk that a person with diabetes will develop diabetic retinopathy. These include:

• High cholesterol levels

• High blood pressure

• Smoking

• Being of African, Hispanics, or Indian descent.

People in these groups who have diabetes have a higher likelihood of developing retinopathy than people of other races with diabetes.

Signs and symptoms

It's very possible to have diabetic retinopathy without knowing it. In early stages there are often no symptoms. As the condition progresses, however, you will likely notice a variety of symptoms, such as:

• An increasing number of ''floaters," those specks that float across your line of vision

• Blurry vision

• Seeing flashes

• Having distorted vision

• Seeing a blank or dark area in your visual field (blind spots)

• Seeing dark spots across your field of vision

• Having poor vision at night

• Noticing that colours appear faded or washed out

• Difficulty reading or doing detail work

• Losing vision

Diagnosis

Regular eye exams are crucial to detect diabetic retinopathy and, if it is diagnosed, to monitor the condition. If you are diagnosed with type 2 diabetes, you should get an initial eye exam as soon as possible and then annually thereafter. Those with type 1 diabetes should be checked within five years of the diagnosis and then every year after. Tests that may be used to diagnose diabetic retinopathy include:

Dilated eye exam. During an exam your eye doctor will put drops into your eye to dilate, or widen, your pupil. Then look through a special lens to examine your eye.

Optical coherence tomography to look at the retina by scanning the retina to get detailed imaging of its thickness.

Flourescein angiography, which involves injecting a dye into a vein in your arm after your eyes are dilated. Then pictures are taken as the dye circulates through the blood vessels of the eyes. The images can show the vessels that are leaking, broken, or closed down.

Stages

Early: In this stage, the blood vessel walls in the retina weaken and bulge. These changes won't be detectable by a patient, but an eye doctor can see them during an examination. This stage is also called non-proliferative retinopathy.

Advanced: Also called proliferative retinopathy, this stage is accompanied by the retina beginning to grow new blood vessels. The new vessels are fragile and can bleed into the area of clear gel between the lens and the retina (vitreous). When this occurs, patients may notice dark spots that float around in the field of vision. If bleeding continues, and there is a large amount, vision may become completely blocked.

Treatments

Getting treatment can help repair damage to the eye and even prevent blindness in most people. Exactly what treatment your doctor will recommend is based on what the exams show, as well as which treatment is considered suitable for your personal situation. At present, management of blood glucose levels is considered the most effective treatment for diabetic retinopathy.

Anti-VEGF treatments: Medicines called anti-VEGF inhibitors block a substance called vascular endothelial growth factor, made by cells, that stimulates the blood vessel growth. The medications help to stop the growth of new blood vessels.

Corticosteroids: These drugs are no longer a mainline therapy for diabetic retinopathy, but they still have a role since there is a component of inflammation with diabetic retinopathy, and the steroids tamp that down. Sometimes, steroids are used in combination with anti-VEGF medications.

Laser therapy: This treatment, also called laser photocoagulation, creates a barrier of scar tissue that slows the growth of new blood vessels.

Vitrectomy: This surgical procedure involves removing all or part of the vitreous, also called the vitreous body. This is the clear gel that fills up the space between the lens and the retina of the eyeball.

Contact Dr Maxwell on 363-1807 or 757-5411.