Age-related macular degeneration (AMD) is the main cause of new cases of blindness among people over 65. It is an eye disease causing increasing concern among health professionals. In Hong Kong, the number of patients suffering from this disease has also increased rapidly in recent years.

Do we have the problem?

In some cases, AMD advances so slowly that the people who are inflicted hardly notice any difference; in other cases, however, it progresses at a much faster pace that it eventually leads to the loss of vision of one or both eyes. Worse yet, the damage sometimes is beyond repair. The combination of early detection and treatment in a timely manner is the key to the success in combating AMD.

Macula is a tiny area in the central part of the retina that helps produce sharp, central vision required for "straight ahead" activities such as reading, sewing, shopping, reading mail, writing, cooking and driving. A person with AMD loses this clear, central vision and also part of his color perception.

What are the symptoms?

• deterioration of central vision
• distortion of central images
• straight line becomes a waxy line
• dark or empty spaces that block the center of vision.
• peripheral vision usually remains normal

Types and classifications

Clinically AMD can present in different severity.

Early presentation is in general mild with small drusen (metabolic waste) being seen deposit below the retinal layer. Vision should be good in this stage.　

With time, the disease will gradually evolve into either dry or wet type.

Dry or atrophic type is the commonest, vision may be affected but usually less and in a very slow progressive manner. In the advanced disease, a large atrophic area can be seen in the macular area. Up to now, no promising treatment is available in this group of disease.　

Wet or neovascular type is however the most important type in causing a rapid drop in vision. It associates with a new growth of vessels beneath the retina that can cause spontaneously leakage and bleeding. Most of the legal blindness in AMD is due to development of the new vessels. Modern technologies and treatment are mainly taking the management of this group of disease.

Check your macular function with the Amsler Grid, a chart that may be helpful in revealing signs of wet AMD.

• Hold the Amsler Grid at eye level at a comfortable reading distance.
• If you wear any type of reading lenses, wear them during the test.
• Cover one eye at a time, and focus on the center dot.
• If you notice any of the potential signs of AMD like wavy, broken or distorted lines or blurred or missing areas of vision, you should contact your eye doctors immediately.

Remember that the Amsler Grid is not a substitute for regularly scheduled eye exams/tests.

How to make a diagnosis?

Retina examination with dilated pupils is very important in making the diagnosis. In some cases, patients may be required to have the fluorescein angiography or the indocyanine green angiography, investigations that are extremely helpful in planning for any from of treatment.　

The exact cause of AMD is still not known, but most think that the disease is cause by several factors. Smoking and age are the proven risk factors. The others include sun exposure, history of cardiovascular diseases, farsightedness, light skin or eye color and genetics.

Avoid prolonged sunlight exposure, to quit the smoking, intakes of antioxidants or minerals may provide some protection effect on the normal fellow eye or on patient with a strong family history.

Different stages of disease or level of severity may require different modalities of treatment.

Common adopted methods or procedures include

1. Laser photocoagulation
2. Photodynamic therapy



3. Submacular surgery or macular translocation surgery

Photodynamic Therapy Brings Hope to Patients with Macular Diseases
(Provided by the Dept of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong)　

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