Macular degeneration

Macular degeneration is an eye disorder in which the central retina, the macula, becomes damaged leading to reduction in central vision. AMD is still the commonest overall cause of serious loss of vision in Europe and the USA, but normally leaves the outer vision completely normal. It is classified into two types on their appearance, either DRY which is more common, or WET which occurs in 10-15% of cases, but is associated with more profound visual loss.

Ageing is such a strong risk factor for development of this disorder, that it is normally referred to as age-related macular degeneration (AMD). Dry AMD is present in over 50% of those aged 75 years and over, mostly in very mild degrees. Other risk factors for developing it are family history, smoking, long sightedness, light skin or eye colour. It is uncommon in black races.

Dry type: gradual onset of difficulty reading with glasses. Wet type: sudden onset of distortion of straight lines (like a kink).

For any reduction in vision that cannot be corrected with glasses you should consult you r doctor, but urgent advice is necessary if any symptoms of the wet type are noticed, such as distortion of images (kinking of straight lines). Tests that may be necessary include the following.

1. Amsler chart - a squared paper chart is useful for detecting and monitoring distortion of straight lines.


Instructions for use

• Print this page.
• Tape this page at eye level and where light is consistent and without glare.
• Put on your reading glasses and cover one eye.
• Fix your gaze on the center black dot.
• Keeping your gaze fixed, try to see if any lines are distorted or missing.
• Mark the defect on the chart.
• Test each eye separately
• If the distortion is new to you or has worsened, arrange to see your ophthalmologist at once.
• Always keep the Amsler's Chart the same distance from your eyes each time you test.
• Print new copies of Amsler's Chart as needed.
2. Your eye specialist will need to examine the retina in each eye with a bright light, and will use some drops to dilate the pupil, which will make you blurred for a few hours.
3. Fluorescein angiography. A small amount of orange dye is injected into an arm vein, and it allows special photographs to be taken of the macula to see if laser treatment is possible.

There is little hard evidence that there is any preventative treatment for AMD, although most eye specialists recommend a good balanced diet containing leafy green vegetables, carrots and eggs. There is some evidence that nutritional supplements may be beneficial in preventing AMD progression and there are many different commercial brands now available. It is probably best to get advice from an impartial source before starting on these and in the UK the Macular Disease Society website is an excellent source of information.

In the dry type of AMD Low vision assessment and advice on magnifiers and lighting can be extremely helpful in maintaining reading and close work. In Solihull we are fortunate to have excellent low vision services within the NHS at Solihull Hospital and in the private sector at the Midland Eye Institute.

Increasing numbers of patients with wet AMD can be treated with laser treatment, dependent on the fluorescein angiography findings. If the network of blood vessels are outside the centre of the macula and readily visible they are potentially treatable with conventional laser photocoagulation, the so-called "hot laser".

Unfortunately the vast majority of patients have blood vessels encroaching on the central macula and in these cases photodynamic therapy (PDT) may be suitable. This type of laser treatment involves the infusion of a special photo-sensitising dye, Visudyne and the application of a low power red wavelength laser. Normally a course of three-monthly outpatient laser treatments are required, with 3-5 treatments being the norm. Clinical trials have shown that in suitable cases the treatment can be successful in limiting the damage that occurs from wet- AMD, with vision preservation.

Mr. Gibson has had experience of using PDT since its launch in the UK in 1999, and is the lead clinician for the NHS PDT service in Birmingham, which is one of the busiest PDT centres in the country.

Exciting developments are taking place using injectable agents for macular degeneration that are growth factor antagonists. These are drugs that are either given by injection into the eye or at the side of the eye, and work by limiting the growth of abnormal blood vessels within AMD. Examples are Retaane, Lucentis and Macugen . Currently these drugs are undergoing clinical trials but are likely to become licensed for use in the UK by early 2006.

Most macular specialists feel that these agents represent an exciting breakthrough in treatment for Wet AMD, and are likely to be used in conjunction with PDT to get the best possible outcome for patients.