Posterior vitreous membrane findings on OCT related to collagen type IV abnormalities.

Abstract

The pathological mechanisms of abnormal collagen type IV predisposing to macular hole formation in Alport syndrome are hypothesized to be related to defective Bruch's membrane leading to ruptured intraretinal cysts. However, abnormal collagen type IV may also predispose to macular hole formation due to vitreous cortex abnormalities. An observational case series of Optical Coherence Tomography (OCT) findings in three patients. In two patients diagnosed with Alport syndrome and in one patient with a possibly pathogenic genetic variant in COL4A3 we observed a remarkable posterior vitreous cortex with a vitreoschisis-like appearance on OCT. Two of these patients developed a rhegmatogenous retinal detachment, of which one was caused by a giant retinal tear, and one patient developed a macular hole. During surgery, a firmly adherent vitreous cortex was observed centrally in the left eye and in the midperiphery in the right eye in one patient with a macular hole and giant retinal tear, respectively. These new vitreous cortex findings in patients with Alport syndrome are possibly related to pathogenic genetic variants affecting type IV collagen. Abnormal type IV collagen may cause pathological vitreoretinal traction, potentially leading to an increased risk of macular holes and rhegmatogenous retinal detachments.