Oval defect in detached posterior hyaloid membrane in idiopathic preretinal macular fibrosis.

We examined the vitreous of 71 eyes with idiopathic preretinal macular fibrosis and observed complete posterior vitreous detachment in 48 eyes (68%), partial posterior vitreous detachment in 16 eyes (22%), and no posterior vitreous detachment in seven eyes (10%). Among the 48 eyes with posterior vitreous detachment, we observed that the detached posterior hyaloid membrane had an oval or round defect in 31 eyes (65%) and a break in the premacular area in 12 eyes (25%). The size and the contour of the premacular defects in the posterior hyaloid membrane corresponded to those characteristic of premacular fibrosis. A premacular oval defect in the detached posterior hyaloid membrane indicates that the vitreous cortex is a structural component of idiopathic premacular fibrosis. We postulate that the thin, premacular vitreous cortex, which forms the posterior wall of the premacular liquefied pocket, plays a key role in the development of idiopathic preretinal macular fibrosis in eyes with or without posterior vitreous detachment.