Functioning avascular retinae—a report of two siblings

Abstract

Introduction: We present two siblings who, despite having complete retinal vessel absence, have functional retinae. Methods: Retrospective case reports Results: Two sisters, aged 3 (SK) and 5 (AK), of consanguineous parents, presented with poorly controlled congenital glaucoma. AK had a right phthisical eye and uncontrolled glaucoma in the left. She demonstrated degraded electroretinograms (ERG) in the right eye but no consistent flash visual-evoked potentials (VEP). SK had uncontrolled glaucoma and dense cataract in the left eye with moderately controlled glaucoma in the right eye. She demonstrated normal ERG in the right eye but no consistent responses in the left eye. Both children had microspherophakia, marked iris hypoplasia, and anomalous dentition. Homocystinuria was excluded serologically. AK had a right vitreolensectomy with subsequent control of glaucoma with topical Cosopt®. SK underwent combined left trabeculectomy and trabeculotomy with mitomycin C, with subsequent lensectomy. The right eye glaucoma was controlled topically as for AK. Clinically SK was able to navigate in familiar surroundings and play with toys close to her face. Both children showed absence of retinal vasculature. Discussion: These are the first reported cases to the best of our knowledge of functioning avascular retinae. AK has little or no vision secondary to glaucoma, although ERG responses are present. SK has functioning vision with normal ERG in the right eye. Conclusions: Physiologically avascular retinae occur in the mammalian world in which the entire metabolic demands are met by the choroidal circulation. These cases may represent a similar entity and in so doing contravene the accepted hypothesis that an avascular retina precludes functional vision in humans.