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Radiation therapy for ocular choroidal neovascularization (phase I/II study): preliminary report
Summary
External photon beam radiotherapy shows promise for treating choroidal neovascularization (CNV). A 20 Gy dose demonstrated greater efficacy in reducing neovascular membranes compared to 10 Gy, with no significant visual acuity loss.
Area of Science:
- Ophthalmology
- Radiation Oncology
- Medical Physics
Background:
- Choroidal neovascularization (CNV) causes severe vision loss in conditions like age-related macular degeneration (ARMD).
- Traditional laser photocoagulation for CNV has limited indications due to significant visual acuity reduction.
- Emerging research suggests low-dose irradiation may benefit subretinal neovascular membranes.
Purpose of the Study:
- To assess the toxicity and efficacy of external photon beam radiotherapy for choroidal neovascularization (CNV).
- To evaluate different radiation doses (10 Gy vs. 20 Gy) for CNV treatment.
- To compare radiotherapy outcomes with a historical control group.
Main Methods:
- A Phase I/II study treated 36 patients with CNV (34 ARMD, 2 angioid streaks) using 10 Gy/5 fractions or 20 Gy/10 fractions.
- CT simulation enabled precise treatment planning for the macula and optic disc.
- A single lateral 6 MV photon beam was used, angled to spare the lens and contralateral eye. A retrospective control group was analyzed.
Main Results:
- No significant acute morbidity was observed.
- The 20 Gy dose group showed significant regression of neovascular membranes, unlike the 10 Gy group.
- Patients in both irradiated groups maintained visual acuity, contrasting with the control group's significant decrease.
Conclusions:
- External photon beam radiotherapy appears effective for treating CNV.
- A dose of 20 Gy in 10 fractions was more effective than 10 Gy in 5 fractions for neovascular membranes.
- Results support initiating a multicenter randomized prospective study for CNV radiotherapy.