Fluorescein and OCT Angiographic Evaluation of Choroidal Neovascular Membrane Following Proton Beam and Intravitreal Anti-VEGF Therapy for Exudative AMD: 2-year Follow Up

Abstract

Purpose : To assess changes in choroidal neovascular membrane (CNVM) on fluorescein angiography (FA) and OCT angiography (OCTA) in eyes with exudative AMD (eAMD) following treatment with low dose proton beam irradiation (PBT) combined with intravitreal anti-VEGF therapy

Methods : Of 30 subjects with eAMD enrolled in a 2-year prospective, sham-controlled, randomized study of PBT combined with intravitreal anti-VEGF (ranibizumab 0.5mg or bevacizumab 1.25mg), interim subset analysis of subjects completing 2-year examination, FA and OCTA were reviewed. All eyes showed new subfoveal CNVM at enrollment, and were randomized 1:1:1 to sham radiation, 16 GyE PBT, or 24 GyE PBT. Patients received 3 monthly anti-VEGF treatments and were followed monthly for 24 months. Retreatment with anti-VEGF was given as needed for macular hemorrhage or fluid on OCT. FAs at baseline and month 24 were compared for change in CNVM size or leakage. Research-grade OCTA was performed to evaluate retinal, choroidal and CNVM vascular flow at follow up. The number of intravitreal anti-VEGF injections was recorded.

Results : Ten subjects had FA at month 24 (5 received sham radiation, 4 received 24 GyE, 1 received 16 GyE). The mean (+/- SEM) baseline CNVM size was 5.64 +/- 1.56 mm² (0.19 to 14.87). The mean change in CNVM size was 45% +/- 29% (-24% to 134%) in the sham group, and 30% +/- 53% (-74% to 173%) in the 24 GyE group (p=0.81). The mean area of maximum leakage on FA at baseline was 5.94 +/- 1.76 mm² (0.68 to 17.66). The mean change in CNVM leakage area on FA compared to baseline was 29% decrease in the sham group and 91% decrease in the 24 GyE group (p=0.34). The number of anti-VEGF administrations among the PBT treated eyes was 4.8 +/- 1.3 (3 to 7), versus 8.6 +/- 1.8 (6 to 14) in the sham group (p=0.14). OCTA was performed in 4 eyes; all showed normal retinal vascular flow on OCTA with reduced detectable flow within CNVM after PBT.

Conclusions : Although this interim subset analysis of an ongoing Phase I/II study showed no significant difference in change of CNVM size among eAMD eyes treated with anti-VEGF monotherapy when compared to eyes treated with combination PBT and anti-VEGF, there was a trend for greater reduction in CNVM leakage and less need for anti-VEGF in eyes treated with combination therapy, which partly may be from reduced CNVM vascular flow.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.