There has been increasing use of photodynamic therapy (PDT) to treat neovascular AMD since FDA approval in 2000. PDT has been shown to be effective in slowing the visual deterioration associated with some types of neovascular AMD. In addition, this treatment is well tolerated without significant systemic adverse events.
PDT relies on the tissue presence of a photosensitizing agent or dye that is subsequently activated by specific wavelength of light. The only such agent currently approved is verteporfin (Visudyne).Following the infusion of the dye, it accumulates preferentially in areas of choroidal neovascularization (CNV), the abnormal tissue causing visual loss in neovascular AMD. Upon interaction with the light, the dye is transformed into an activated state resulting in damage and sclerosis of the CNV.
The dye is first infused intravenously for 10 minutes. Fifteen minutes after the start of the infusion, a laser light is delivered over the affected area for 83 seconds.It is important for patients to avoid direct sunlight or bright light for 5 days after treatment to avoid photosensitivity reactions. They should stay indoors during this time and limit skin exposure with the use of long protective clothing. Sunscreen cannot be used as a substitute since it will not prevent damage to the skin with exposure.
For at least the first two years following PDT, follow up visits are needed to determine if additional treatment needs to be done.
Side effects of the treatment include:
- mild and temporary visual disturbances
- photosensitivity
- injection site reaction
- severe allergic reaction
