Morphologic characteristics of disciform scarring after radiation treatment for age-related macular degeneration

To investigate the influence of radiation therapy on the development of disciform lesions in patients with age-related macular degeneration (AMD).

A prospective, nonrandomized, comparative trial (patient self-controlled).

Forty eyes with exudative AMD involving the central fovea in 40 consecutive patients were enrolled in this study.

Radiation was administered to the posterior pole with an 8-mV photon beam from a linear accelerator. A dose of 14.4 Gy, 1.8 Gy per day, five fractions per week was delivered through a single port.

The visual acuity and the morphologic characteristics, demonstrated by fundus photography, fluorescein, and indocyanine green angiography, were investigated before treatment and every 3 months after treatment over a period of 24 months. In 10 patients with bilateral disease the disciform lesions were compared.

Twenty five patients could be followed regularly over the period of 24 months. The disciform lesions occurring after radiation were classified in three types. Type I (10 patients) was characterized by being smaller than 2 DD in size, with little fibrotic tissue underneath the retina, but pronounced retinal pigment epithelial changes. Type II (seven patients) showed extensive growth of the choroidal neovascularization (CNV) extending to and beyond the arcades with angiographically active loops in the peripheral parts. Eight patients had type III lesions develop characterized by a size greater than 2 DD but fewer than 6 DD and by a different amount of fibrotic tissue, hemorrhage, and lipid. Type I scarring was significantly associated with occult CNV without pigment epithelial detachments, whereas type II scarring was associated with classic CNV at the initial presentation (P<0.05).

Although no severe side effects have been reported after radiation therapy for AMD, a subgroup of patients may experience extensive growth of CNV after radiation, causing greater functional damage than occurs spontaneously.