Long-term OCTA Analysis of Exudative Age-Related Macular Degeneration Eyes Treated with Low Dose Proton Beam and Intravitreal Anti-VEGF

Abstract

Purpose : To describe the OCTA findings in exudative age-related macular degeneration (eAMD) eyes treated with proton beam therapy (PBT) and anti-VEGF intravitreal injections as part of a Phase I/II randomized study.

Methods : Retrospective OCTA analysis (Cirrus Angioplex, v10) of the macula of both eyes in 11 eyes with newly-diagnosed eAMD that completed a prospective, sham-controlled, double-masked study, randomized 1:1:1 to 24GyE, 16GyE, or sham radiation and treated with three monthly intravitreal ranibizumab or bevacizumab injections and as needed re-injections thereafter based on monthly examination and OCT.

Results : Mean follow-up after PBT or sham radiation was 58.8 months. Six eyes had PBT (5 had 24GyE, 1 had 16GyE; 3 contralateral eyes had eAMD), and 5 eyes had sham radiation (2 contralateral eyes had eAMD). The mean retina vascular density (RVD) of the central 1mm zone of the macula in PBT-treated eyes was 4.06 mm/mm² and 8.54 mm/mm² in sham-radiated eyes (p=0.06). The mean ETDRS inner-ring RVD in PBT-treated eyes was 10.33 mm/mm² and 14.24 mm/mm² in sham-radiated eyes (p=0.06). The mean FAZ area was 0.30 mm² in PBT-treated eyes and 0.48 mm² in sham-radiated eyes (p=0.24). The difference in mean RVD for the central 1mm zone of the macula between the study eye and contralateral eye was 0.525 mm/mm² in the sham group and 2.57 mm/mm² in the PBT-treated group (p=0.24). The mean difference in the inner-ring RVD between the study eye and contralateral eye was 0.525 mm/mm² in the sham group and 2.13 mm/mm² in the PBT-treated group (p=0.52). The mean difference in FAZ area between the study eye and contralateral eye was -0.26 mm² in sham group and -0.04 mm² in PBT-treated eyes (p=0.04). The choriocapillaris layer showed flow loss only within areas of geographic atrophy (GA) in study eyes.

Conclusions : Although there is a trend toward decreased RVD in the macula in PBT-treated eyes when compared to sham-radiated eyes, the RVD of the PBT-treated eyes was not decreased when compared to that of the contralateral eye. Similarly, the FAZ size was not increased in PBT-treated eyes treated when compared to the contralateral eye or sham-radiated eyes. No choriocapillaris loss was noted outside areas of GA in all PBT-treated eyes. The findings of this limited case series show no significant long-term adverse effect of PBT on retinal or choroidal perfusion in eyes with eAMD.

This is a 2020 ARVO Annual Meeting abstract.