Age-related macular degeneration

Age-related macular degeneration (ARMD) is a common cause of reduced vision in the UK. As the name suggests, it is a condition that tends to become more common in elderly population.

As ARMD affects the macula or the central sensitive part of the retina, it causes reduction to complete loss of central vision but not complete blindness as the peripheral vision is left intact.

The macula is the central part of the retina that is responsible for seeing fine detail, such as reading, seeing facial features and interpreting different colours. It is this part of the retina that is affected by age-related macular degeneration.

Causes of ARMD

It is a process of ‘wear and tear' changes in the macular region. It is thought that waste materials from this very active part of the eye build up as the mechanisms for removing them become less able. This causes damage to the cells over a period of time.

Risk factors

This condition tends to affect people who are over 60 years of age. Extensive exposure to UV radiation has been proposed as one of the mechanisms causing macular degeneration. Some younger people may be more susceptible, including people who are very short-sighted. Women tend to be affected more commonly than men, but that is probably because they live longer.

Types of macular degeneration

There are two major types of ARMD. These are described as dry or wet.

Dry ARMD

This is the more common form of ARMD and affects almost 80 per cent of those with the condition. The onset of this condition tends to be slow. Both eyes are usually affected

Wet ARMD Wet macular degeneration is less common but tends to have a more severe and rapid effect on the central area of vision. In this condition, blood vessels from one layer at the back of the eye grow in an abnormal fashion into the macular area. These blood vessels may leak or bleed causing a rapid and significant reduction in central vision. This tends to affect one eye at a time but there is a risk of the same thing occurring in the other eye over the following months.

Symptoms of age-related macular degeneration

Dry ARMD causes a gradual reduction in central vision. This tends to affect the ability to read and to see fine detail more than distance vision.

The first symptoms of wet ARMD may be distortion of vision (known as metamorphopsia). This often has the effect of making straight lines appear curved or tilted. The vision deteriorates and eventually the central vision may be completely lost leaving a dark central area of poor vision (known as a central scotoma).

Treatments for ARMD

Dry ARMD

The vision tends to deteriorate gradually and the loss of vision is not always severe. Unfortunately there is no treatment as such for the dry type.

But some practical measures such as possibly using bright lights for example halogen light to help you see things more clearly. The use of large print books and the prescription of a magnifying glass (low visual aid) are often necessary.

Wet ARMD

In order to determine whether a patient would be suitable for treatment, further evaluation in the way of visual assessment with special letter charts and imaging of the retina can be carried out. Imaging of the retina involves a fluorescein angiogram and indocyanine green angiogram which show the pattern of the blood vessels in the retina and whether treatment would be effective.

The fluorescein angiogram and the indocyanine green angiogram procedure involves a dye being injected into a vein of the arm and then a series of photographs are taken of the back of the eye

An Optical coherence tomogram OCT scan is used to look for macular degeneration under the retina and this scan usually takes only a few minutes to perform.

If wet ARMD is confirmed, treatment is implemented urgently.
Photo-dynamic therapy (PDT) in which a light sensitive dye called verteporfin is injected up the arm which travels to the back of the eye and then the dye is activated with a laser shown through the eye. Please note not all types of wet ARMD are amenable to this type of treatment.

Ranibizumab is a drug that binds to certain chemicals in the eye preventing their action which would otherwise stimulate the growth of the abnormal blood vessels in the macula. This drug is injected into the eye.

Please consult the online doctor for bespoke, evidence based and confidential medical advice.