Age related macular degeneration or AMD is the leading cause of irreversible visual loss in people over the age of 65 in the US. Approximately 10-20% of patients with AMD develop choroidal neovascularization (CNV). In the US, 100,000 to 200,000 people develop CNV every year. The population at risk will double in size over the next 30-40 years in the Western world. AMD results in a tremendous burden to the individual and society. The individual often loses central vision in one eye, and is extremely anxious about losing the vision in the fellow eye. There is loss of the ability to work, loss of recreation, socialization and increased dependance on others. These patients comprise about 40% of many retinal practices. The are multitude of diagnostic and treatment modalities including fluorescein and ICG angiography, laser treatment, photodynamic therapy, transpupillary thermotherapy, and surgery.

The causes are not completely understood, but it seems that age is the greatest risk factor. AMD increases in frequency with age and the advanced form affects approximately 8% of the population over the age of 75. Heredity, sun exposure, smoking, and diet are other possible factors. The most consistent risk factor for AMD is cigarette smoking. Smokers have a two to three fold increased risk of developing this disease. Nutritional factors may play a role and prospective studies, as well as randomized trials, are underway to further evaluate these relationships. Some data suggest an association between AMD and cardiovascular risk factors. Patients who consume green leafy vegetables seem to have a lower incidence of both dry and wet AMD.

The retina is a thin, light sensitive layer that lines the inside of the back of the eye. It is similar to the film in a camera. The macula or center of the retina only covers about 5% of the retina, but is responsible for the most sensitive central vision and the remainder of the retina is for side vision. AMD causes progressive damage to the macula. When the macula is not functioning properly, one may experience blurring, distortion, or darkness in the center of the field of vision. Near vision such as reading is affected more than distance vision. AMD almost never causes total blindness.

There are two types of AMD, the dry or atrophic variety and the wet or exudative type. Dry AMD is much more common and accounts for 90% of all AMD. It cannot be treated with medication or surgery, but many patients can function well with magnifying and telescopic lenses. The dry type is not necessarily a precursor to the wet type.

The wet form is less common, but more severe than the dry form. It accounts for 10% of all cases of AMD, but 90% of the blindness from the disease. Wet AMD is characterized by abnormal blood vessels that grow under the retina called choroidal neovascularization, or CNV. These abnormal blood vessels usually leak fluid and bleed, which leads to scarring under the center of the macula and results in profound loss of central vision. The natural course or history is quite poor, with 64% of patients losing 6 or more lines of vision over a 2 year period. Conventional laser treatment can be offered when the abnormal blood vessels have not yet extended under the center of the macula. Only about 13% of patients with CNV are eligible for conventional laser treatment. This does not cure the AMD, but merely destroys that specific blood vessel complex. Some patients may have an immediate decrease in central vision with a central or paracentral scotoma (blind spot). Recurrent CNV can occur up to 40% of the time and may or may not be amenable to retreatment.

Fluorescein angiography is a technique that is used to evaluate the macula. A dye is injected into a vein in the arm and photos are taken as the dye circulates through the retinal blood vessels. This helps to determine the type and location of the CNV. Sometimes indocyanine green angiography is used as well when the CNV is more difficult to visualize than with conventional fluorescein angiography.

Antiangiogenic treatments for subfoveal CNV including interferon alfa-2a and isotretinoin have not been found to be beneficial. Nor has radiation therapy shown to have any effect. There are several new promising treatments for wet AMD. Photodynamic therapy (PDT) with Verteporfin is a treatment that uses nonthermal lasers to activate photosensitive drugs that are injected into an arm vein and reach the retina. A much less powerful laser is able to be used that is not likely to damage the healthy tissue surrounding the abnormal CNV.

Other experimental treatments include surgical removal of the CNV. The results are promising for causes of CNV other than AMD, but disappointing when the etiology is AMD. Retinal translocation is a surgical technique that displaces the fovea to a new location where the underlying retinal pigment epithelium and choriocapillaris are healthy. This is major surgery with significant risks. Limited translocation surgery is safer but certainly not without risks as well. The role of macular translocation in the treatment of subfoveal CNV is yet to be established, but newer surgical techniques that are more predictable, associated with fewer complications, and allowing for greater foveal displacement are making this procedure safer and more effective.

In conclusion, it is important to remember that the earlier the diagnosis the more likely the treatment is to be successful. Check your vision in each eye every day, preferably with an Amsler grid card, and notify your doctor if there is any change, especially distortion or blurriness.