The retina is like the film in a camera. It is the third and inner coat of the eye — a light-sensitive layer of tissue. When focused light hits the retina, a picture is created and sent to the brain through the optic nerve, giving us vision.

Sometimes part of the retina tears, pulls away or detaches from the back of the eye. When this happens, that part of the retina cannot gather light, and the result is loss of vision.

Diseases and conditions of the retina

• Age-related macular degeneration
• Diabetic retinopathy
• Retinal tear
• Retinal detachment

What causes AMD?

During normal ageing, yellowish deposits called drusen form under the retina, the light-sensitive layer of tissue at the back of the eye that provides clear, sharp images.

As drusen increase in size and number they can interfere with the retina, damaging or killing the light-sensitive cells of the macula. Because these cells give us sharp, detailed vision, the result can be blurring of central vision — and a real impact on reading, driving, or even recognising the face of a friend.

This form is called dry AMD. Dry AMD can be a precursor to wet AMD.

Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These vessels often leak blood and fluid, damaging light-sensitive cells, and vision is lost quickly. Although about 80 percent of people with AMD have the dry form, wet AMD is responsible for 80 to 90 percent of severe vision loss from the disease.

Living with AMD

AMD can be a difficult condition, but it is not as devastating as people fear when they are diagnosed, and it only rarely leads to complete blindness. Many people live healthy, independent lives with it.

It is important to learn about the disease and work with a retina specialist, who will put a treatment plan in place and can suggest rehabilitation options such as low-vision aids that make everyday living a little easier.

Symptoms

A retina specialist can detect the earliest signs of AMD before you have any vision loss. Those who have had the disease for some time may notice these changes:

Pay close attention to any decline in central vision, near or distant. If you notice any of these signs, book an examination with a retina specialist.

Risk factors

The main risk factor for AMD is age — the older you are, the greater the risk. People with a family history of AMD are at higher risk, as are women and people of European descent. Some lifestyle factors also raise the risk:

• Cigarette smoking
• Obesity
• High blood pressure
• Excessive sun exposure
• A diet low in fruits and vegetables

Diagnostic tests

Treatment

There is no known cure for AMD, but early detection and proper treatment can protect vision from further deterioration.

Intravitreal injections

The anti-VEGF medicines used for wet AMD include:

• Pegaptanib (Macugen)
• Bevacizumab (Avastin)
• Ranibizumab (Lucentis)

A tear can result from ageing, an injury to the eye, or another eye problem. A retinal detachment occurs when fluid passes through the tear and separates the retina from the back of the eye.

Flashes, a sudden shower of floaters or a shadow over part of your vision need an eye examination the same day.

Sealing a tear — pneumatic retinopexy

Used when the tear is small and easy to close. A small gas bubble is injected into the vitreous gel, where it rises and presses against the retina, closing the tear. Laser or cryopexy then seals it. Each of these treatments fixes the retina to the back of the eye and stops the tear getting worse.

Treating a retinal detachment

Depending on how complex the detachment is, vitrectomy, buckle, laser and gas bubble may be combined to repair the retina.

Diabetic retinopathy is a complication of diabetes that affects the eyes. It is caused by damage to the blood vessels of the retina: when blood sugar stays too high, it harms the small vessels at the back of the eye. It can lead to vision loss or blindness — but there are steps you can take to reduce the risk.

Symptoms

Diabetic retinopathy usually affects both eyes.

• Spots or dark strings floating in your vision (floaters)
• Blurred vision
• Fluctuating vision
• Impaired colour vision
• Dark or empty areas in your vision
• Vision loss

Causes

High blood sugar can damage the small vessels that nourish the retina, and sometimes block them completely, cutting off its blood supply. In response the eye may produce growth factors that lead to diabetic macular oedema, which lowers vision, or proliferative diabetic retinopathy, which can lead to retinal detachment.

Risk factors

• Duration of diabetes — the longer you have had it, the greater the risk
• Poor control of blood sugar
• High blood pressure
• High cholesterol
• Pregnancy
• Tobacco use

Complications

Stages

Detection and prevention

There are no symptoms in the early stages, when retinopathy is easiest to treat. By the time vision changes, it is often late — so every person with diabetes needs regular eye check-ups.

• Routine eye examination, as often as your eye doctor advises
• Good control of diabetes
• Control of blood pressure and cholesterol
• Stopping smoking and alcohol

Investigations

Diabetic retinopathy is best diagnosed with a dilated eye exam, in which the doctor looks for abnormal or new vessels, swelling, blood or fatty deposits, scar tissue, bleeding in the vitreous, retinal detachment and changes in the optic nerve. The doctor may also check vision, measure eye pressure and look for cataract.

Treatment