Secondary choroidal neovascular membrane in a patient with type 1 retinochoroidal coloboma after barrage laser

Abstract

A 32-year-old woman presented at the Retina Clinic, Aravind Eye Hospital, Pondicherry, with recent-onset vision loss in her right eye. History included barrage laser in the right eye performed at another institution 6 months before presenting at our clinic. On examination, her visual acuity was counting fingers at 2 meters in the right eye and no light perception in the left eye. The right eye had an iris coloboma; the left eye was phthisical. Fundus examination of the right eye (A) showed inferior retinochoroidal coloboma, with intercalary membrane breach (black arrows), with the edge overlapped by laser scars at the site of probable choroidal neovascular membrane (white arrow), and hemorrhage (blue arrows) adjacent to the laser marks, at the edge of the coloboma. Fundus fluorescein angiography revealed presence of type 2 choroidal neovascular membrane, with increasing hyperfluoresence (B-C). The origin of choroidal neovascularization, whether from the coloboma per se or because of laser treatment, is unknown. Because the patient was monocular and symptomatic, we decided to treat with anti-VEGF (bevacizumab) injection at monthly intervals. After the second injection, her best-corrected visual acuity improved to 20/125. Serial optical coherence tomography (D-F) shows subretinal hyperreflective membrane, with subretinal fluid and signs of regression after treatment. Patients with retinochoroidal coloboma can be predisposed to retinal detachment, presenile cataracts, vitreous hemorrhage, and choroidal neovascularization. The discontinuity of Bruch’s membrane at the margin provides a potential pathway for growth of a neovascular membrane. Surgical management of retinal detachment due to breaks in the intercalary membrane is challenging, and barrage laser plays a role in prevention of retinal detachment in these patients.