The retina and macula

What does the retina do?

The retina is the thin, light-sensitive layer at the back of the eye. It turns light into nerve signals, and the optic nerve carries them to the brain. The macula is the centre of the retina, and sharp sight, reading and recognising faces depend on it.

Diabetic retinopathy

Over time diabetes damages the tiny vessels of the retina. More than half of people with diabetes eventually develop this, and the risk rises with the years of diabetes.

Early on there are usually no symptoms. Later, vessels may bleed inside the eye and you may see dark floating spots or cobweb-like streaks.

To lower the risk:

• Keep your blood sugar in the range your doctor has set.
• Control your blood pressure and cholesterol.
• Have a full dilated exam at least once a year.
• If you are pregnant and have diabetes, get an exam as soon as you can.

Depending on the stage, treatment may be injections into the eye, laser or a vitrectomy operation. It can prevent further loss but does not reverse existing damage.

Age-related macular degeneration

Here the centre of the retina is damaged with age. The dry type is more common and progresses slowly. The wet type is less common but takes sight faster, as abnormal vessels grow under the macula.

Age over 55, family history and smoking are risk factors. Wet AMD is treated with injections into the eye. At certain stages of dry AMD, specific supplements can slow progression; ask your doctor rather than starting them yourself.

If straight lines look wavy or bent, call an eye doctor at once.

Floaters and flashes

Nearly everyone gets floaters with age. The gel inside the eye slowly clumps, and the clumps cast shadows on the retina. Floaters that have been there a long time, are not getting worse and do not affect your sight are usually harmless.

Retinal tear and detachment

Retinal detachment is a medical emergency. The signs are:

• A sudden increase in floaters
• Flashes of light in one or both eyes
• A curtain-like shadow over part of your vision

Severe short sight, past eye surgery, serious injury, diabetic retinopathy and a personal or family history raise the risk.

Small tears are usually treated with laser or freezing. Larger detachments need surgery, and sometimes several methods are combined. Delay can let more of the retina detach and raises the risk of permanent loss of sight, so with these signs go to an eye doctor or the emergency department at once.