Omni Eye Specialists - Services - Retina

Age Related Macular Degeneration (AMD)

Macular Degeneration is a troubling disease and is usually found in individuals over the age of 50. In most cases, the disease affects both eyes and progresses very slowly. Visual symptoms of ARMD involve loss of central vision. Thus, those activities utilizing central vision are the most affected, such as reading, driving and watching TV. It is important to point out that macular degeneration does not lead to blindness as peripheral vision is unaffected

Ninety percent (90%) of patients have the so-called “dry” form of macular degeneration. This form is slowly progressive and patients rarely suffer from severe vision loss. There is often little that needs or can be done.

Fewer patients suffer from the “wet” form of the disease. Abnormal “leaky” vessels grow between the layers of the retina. Fewer than 10% of all patients develop wet ARMD. Substantial loss of central (e.g. reading) vision may be lost in on a few weeks to months. Ocular Photodynamic Therapy (OPDT) was approved several years ago and is the mainstay to treating patients with subfoveal choroidal neovascularization. It selectively inhibits growth of the abnormal blood vessels, thus usually preserving, and sometimes, improving central vision. Other treatments will be emerging in the next few years.

Photodynamic Therapy (PDT) for the Treatment of Exudative ARMD

Since FDA approval of Visudyne (Verteporfin for injection, Novartis), Photodynmic Therapy (PDT) has become the mainstay of treatment for patients with subfoveal or submacular choroidal neovascularization. Stated another way, patients with the wet form of the disease that develop abnormal blood vessels underneath the macula respond well to this new treatment. PDT is a treatment that usually needs to be repeated. Most patients may require 3-4 treatments over the first year and about 2 treatments over the second year. Significant preservation of vision can be acheived when adhering to this protocol. Many patients may also improve vision after initial treatment with subsequent treatments able to sustain this improvement.

PDT involves injection of a medicine (Verteporphin) which will accumulate in the abnormal vascular complex. This infusion occurs over a 10 minute period. The amount of drug administered is based upon the body mass index (BMI) which is a derivation based upon the individual’s height and weight. A “cold” or nonthermal laser (689 nm) is applied for 83 seconds to convert the accumulated Verteporphin to a form which is toxic to the abnormal blood vessels. In this way only the abnormal tissue is affected and surround normal tissue remains unaffected! This is in contrast to initial treatments using thermal lasers.

Vitamins and ARMD

Vitamin supplementation has been proven helpful to only a small subset of patients with ARMD as described by the Age-Related Eye Disease Study (AREDS). The full study can be found at http://www.nei.nih.gov/amd/. Vitamins can reduce the chance of severe vision loss from choroidal neovascularization by 25%, but these effects are found only in the highest risk group. Advertisements for these nutritional supplements seem to indicate that vitamin supplementation is beneficial for all patients with macular degeneration.

Bausch and Lomb originally formulated the vitamins used in the AREDS study. This formulation is sold over the counter as Ocuvite® PreserVision®. Other companies now market similar compounds.

Other Treatments for ARMD

Classic photocoagulation using a thermal laser was the first line of treatment and was described in the Macular Photocoagulation Study Group in the early 1990’s. Its main drawback is the formation of permanent black spots or “scotomas” in the patient’s vision. This is one reason why PDT has become so popular. Still there are cases where this treatment may be preferred, for example, in cases where the neovascularization is not directly underneath the macula.

Transpupillary Thermotherapy Technique (TTT) utilizes a lower energy diode laser to treat the neovascular complex. The adjacent cells, the RPE, may be left intact and undamaged. The exact mechanism of action is not known. It may be an attractive alternative to PDT as expensive injections are not needed. Similar techniques have been employed to treat ocular tumors such as retinoblastoma and choroidal melanoma.

Feeder Vessel Treatment with High Speed ICG Angiography is currently under investigation. The dye, similar to fluorescein, is infused to identify a single feeder vessel. If a vessel can be identified and is treatable, the size or total are of treatment is smaller than compared to conventional methods. Treating only this area limits the amount of laser applied to the retina and thus minimize scotoma formation.

Rheopheresis is a method by which certain toxic substances are filtered from the bloodstream. Certain “vascular risk factors” are removed from the blood during treatment. There is evidence suggests that progression of the ARMD may be reduced if these factors, such as LDL cholesterol, fibrinogen and lipoprotein A are reduced. Rheopheresis is understudy.

Promising alternative treatments will involve intravitreal drug injection and delayed intraocular delivery of key medicines that can further inhibit or destroy these “leaky” blood vessels. Present treatments are limited to those patients with the wet form of the disease. Several drugs are understudy and may be approved for patient use in the next 1-2 years.