Swept Source Optical Coherence Tomography Analysis of the Margin of Choroidal Coloboma : New Insights

Purpose: To study the retinal architecture and vitreoretinal interface at the edge of choroidal coloboma using swept-source OCT.Design: Prospective observational case series at a tertiary eye care center.Participants: Patients with choroidal coloboma treated at an ophthalmology department and fulfilling the inclusion criteria of the study.Methods: Swept-source OCT was carried out in 30 eyes of 20 patients with choroidal coloboma.Main Outcome Measures: The primary objective was to describe the OCT features at the margin of the coloboma.Results: Swept-source OCT of the coloboma margin revealed new features in addition to the previously described findings. Two types of transition from normal retina into intercalary membrane (ICM) were noted: abrupt (73.33%) and gradual (26.67%). Outer retinal layers (interdigitation zone and ellipsoid zone) terminated at a variable distance before the retinal pigment epithelium in 56.67% of eyes. Cystic spaces in the ICM (46.67%), schisis-like spitting of the ICM (30%), and breaks in the ICM (6.67%) were seen as well. Subclinical retinal detachment (RD) was also noted in 1 eye. The peculiar features noted at the vitreoretinal interface included vitreous attachment at the coloboma margin (23.33%), vitreous condensation (6.67%), and hill like projections of ICM into the vitreous cavity (26.67%). In the region of the coloboma, sclera and Tenon's capsule could also be analyzed as a hyperreflective lamellar structure and an irregularly arranged less hyperreflective structure.Conclusions: Swept-source OCT of the coloboma margin revealed various new features in addition to those described previously. The detection of subclinical RD or early termination of outer retinal layers in selected cases may be helpful in guiding new management protocols. (C) 2019 by the American Academy of Ophthalmology