Information - Macular Degeneration

The retina of the eye contains millions of light-sensitive nerve cells that convert light into signals that are sent to the brain. The brain then interprets these signals as images, which is what we call vision. A small central area of the retina is called the macula and it is a highly sensitive area that produces detailed and colour images in the centre of the field of vision. The macula is important for everyday tasks. Macular degeneration (MD) occurs when the macula is damaged and usually affects both eyes, but it may produce symptoms in one eye long before the other.

Although MD has many causes, the most common form is related to age. Age-related macular degeneration (AMD) occurs in people typically older than 50 years and especially in those over 65. 15 in every 100 people older than 50 have early signs of MAD, but only one or two become severely affected. Over the age of 75, about 30 people in 100 have early signs, and two or three become severely affected.

The precise cause of AMD is unknown, but the main risk factors appear to be:

·        Increasing age.

·        Smoking.

·        A family history of AMD.

Types of Macular Degeneration

The two types of MD are “dry” and “wet”.

Dry macular degeneration develops slowly as cells in the macula die in small patches, images fade and become unfocussed. No treatment can stop or reverse the condition.

Wet macular degeneration consists of new blood vessels growing from the choroid into the macula. They leak blood and fluid that build up under the retina that leads to deterioration in vision and scar tissue forms in the macula causing severe affects to central vision.

Symptoms of AMD

·        Straight lines appear wavy.

·        Blurred or fuzzy vision.

·        Difficulty in recognising faces.

·        Blurred or blind spot in the centre of vision.

Fluorescein Angiography

Fluorescein angiography is a diagnostic test that provides your optometrist with photographs of the location, size and shape of blood vessels in the retina. This helps diagnosis of the disease and planning of treatment.

A dye called fluorescein is injected into an arm vein and a series of photographs of the retina are taken, accompanied by flashes of light into the eye. If abnormal blood vessels are present, they can be seen on the photographs. This test provides your eye doctor with a “map” for treatment.

Treatment of Wet Macular Degeneration

·        Photodynamic Therapy: Use of a light-sensitive chemical destroys the abnormal blood vessels. The chemical travels to abnormal blood vessels in the retina where it is activated by a special low-energy laser, clotting the abnormal blood vessels. This therapy may be recommended when abnormal blood vessels are well defined and lie under the precise middle of the macula.

·        Laser Photocoagulation: Use of a laser beam to remove an abnormal blood vessel. This is a treatment of choice if the blood vessels aren’t under the centre of the macula.

Treatment Procedure

Drops to enlarge the pupil are put in your eye giving the optometrist a better view of the retina. A special lens is held to the eye to stop the eye blinking and help the optometrist see the retina. Treatment may be completed in one session, but more sessions are usually needed, especially for photodynamic therapy. The aim of laser treatment is to prevent the condition from getting worse – it doesn’t restore lost vision. Laser treatment has no role with dry AMD.

Recovery after Laser Treatment

The pupil remains dilated for a few hours, and vision may be blurred temporarily. You may have a headache if the treatment was lengthy and the eye may feel irritated for the rest of the day. Pain-relieving medication can be taken. If you have had photodynamic therapy, you must stay out of the sun and halogen light for 48 hours.

·        Regular follow-up eye examinations are important so your optometrist can check whether the condition is stable or recurring.

·        Smoking increases the risks of wet AMD and seriously impairs healing.

Possible Complications of Laser Treatment

While your doctor makes every attempt to minimise risks, complications can occur. It is important that you have enough information about side effects and complications to fully weigh up the benefits and risks of surgery.

If you have particular concerns about possible complications, discuss them with your optometrist. It is important for patients to understand that a refusal to have treatment can lead to vision becoming worse.

If vision worsens following treatment, it may be caused by the disease rather than the treatment. Any serious complication could cause poor vision, blindness or even loss of the eye.

These are possible complications:

·        Vision can be blurred for weeks, although in most patients it usually improves within hours or days.

·        The treated eye may have increased sensitivity to glare.

·        Treatment poses a risk of damage to the macula that may reduce central vision.