PHOTODYNAMIC THERAPY WITH VERTEPORFIN AS A LINE OF TREATMENT FOR AGE RELATED MACULAR DEGENERATION

Abstract

Photodynamic therapy is a new therapeutic teclmique which is attracting increasing attention. Its biopharmacological basis of action is the specific interaction of a photosensitizing compound with the cellular elements of pathological lesions. The photosensitizer is thought to enter specifically into the pathological cells; where it accumulates. The lesion is then irradiated with a sensitizing laser beam of specific wave length to activate the photosensitizer which then becomes a generator of free oxygen radicals; these radicals destroy the sensitizer-harboring pathological cells. The advantage of specifically destroying pathological lesions without affecting the surrounding normal tissues is obvious. Many experimental studies have been conducted to test the usefulness of photodynamic therapy for ocular disorders mainly age related macular degeneration; the results are .so far encouraging. (Solberg and Belkin,1997.)

Age related macular degeneration is the major cause of loss of vision in older people and approximately I0% of people aged over 65years have early stage of age related macular degeneration. (Klein et a/.,1992)

Most of the patients with age related macular degeneration have the non neovascular or dry fonn of age related macular degeneration which is characterized by the appearance of drusen and by pigment atrophy and hypertrophy of the retinal pigment epithelial cells. Only small proportion of patients with age related macular degeneration progress to have the neovascular or wet fonn. However, severe loss of vtston occurs predominantly in those patients with the neovascular form of age related macular degeneration. (Ferris et a/.,1984)

The neovascular fonn of age related macular degeneration is characterized by choroidal neovascularization followed by the fonnation of fibrovascular scar tissue. Individuals with choroidal neovascularization due to age related macular degeneration suffer from rapid decrease of their visual acuity and may be legally blind in two years of diagnosis. (Bressler et a/.,1982)