The photon therapy of subfoveal choroidal neovascularization in age-dependent macular degeneration. The results of a prospective study in 40 patients

Abstract

To determine the effect of external beam radiotherapy on subfoveal choroidal neovascularization in age-related macular degeneration. Between September 1995 and July 1996, 40 patients (9 males and 31 females; mean age 74 years, range 61 to 83 years) were included in a prospective study. Eight patients had classic, well-defined neovascularisations, 32 patients had occult lesions. Complete ophthalmic investigations included visual acuity contrast sensitivity as well as fluorescein and indocyanine green angiographic examinations prior to treatment and 1, 3, 6, and 12 months after radiotherapy. External beam radiotherapy (8-MV photons) was delivered with a total dose of 14.4 Gy in 8 fractions of 1.8 Gy per day (Figures 1 and 2). The field size averaged 5.5 x 4.5 cm. No treatment related morbidity during or after treatment was obtained. After 6 months follow-up the visual acuity was improved in 2 (5%) patients and maintained at pretreatment level in 17 (42%) patients. However, 12 months post treatment a stable situation was found in 6 (15%) patients and a decrease in visual acuity in 34 (85%) patients (Table 1). The central visual fields deteriorated significantly from 16.5 decibel (dB) to 12.4 dB. The enlargement of exudates and neovascular membranes increased 5- to 7-fold. At 12 months after treatment, 3 (7.5%) patients stated that they had improved vision subjectively, 12 (30%) patients had no change and 25 (62.5%) patients suffered from subjective decrease in visual acuity. Using a total dose of 14.4 Gy/1.8 Gy no difference concerning visual acuity and exudative changes in comparison to the natural history on age-related macular degeneration was obtained after 12 months. However, the results of multicenter studies are to be awaited.