Macular hole retinal detachment in highly myopic eyes - Ultrastructure of surgically removed epiretinal membrane and clinicopathologic correlation

Purpose: To elucidate the pathogenesis of macular hole retinal detachment (RD) in highly myopic eyes by investigating the ultrastructure of surgically removed epiretinal membranes (ERM). Methods: Five consecutive Japanese patients with macular hole RD in highly myopic eyes underwent vitrectomy with attempted removal of the ERM around the hole. The surgical specimens were examined by light microscopy and by scanning and transmission electron microscopy, Results: Extremely thin, translucent sheets of epiretinal tissue were harvested from all patients during surgery, resulting in successful retinal reattachment. Ultrastructural examination revealed that the ERM consisted of cortical vitreous and various cellular components. Fibrous astrocytes were the major cell population and extended cytoplasmic processes with membrane-associated vesicles onto the cortical vitreous, Gap junctions were observed between the interdigitating processes of fibrous astrocytes. The cortical vitreous contained abundant newly formed collagen, including fibrous long-spacing collagen, surrounded by sparsely distributed native vitreous collagen. Conclusions: Active synthesis of new collagen may be regulated by fibrous astrocytes by means of transmission of metabolic substances through gap junctions and cytoplasmic vesicles. The frequent occurrence of newly formed collagen aggregates may subsequently lead to a diffusely condensed posterior cortical vitreous that exerts tangential traction on the posterior retina, causing macular hole RD.