Fig. 2. Stages of development of an idiopathic macular hole. A. Normal fovea. Layer of vitreous (VC) lying on internal limiting membrane of retina. B. Stage 1A impending hole. Early contraction of outer part of vitreous cortex with foveolar detachment. C. Stage 1B impending hole. Further vitreous contraction and condensation of the prefoveolar vitreous cortex with foveal detachment. D and E. Stage 1B occult hole. Dehiscence of the retinal receptor layer at the umbo with centrifugal retraction of the retinal receptors. F. Stage 2 hole with early separation of condensed prefoveolar vitreous cortex with formation of pseudo-operculum that is larger than the hole. G. Stage 2 hole with tear in vitreous cortex at junction of the prefoveolar vitreous cortex and edge of macular hole. H. Stage 3 hole with pseudo-operculum. I. Stage 4 hole after posterior vitreous separation. (From Gass JD. Reappraisal of biomicroscopic classification of stages of development of a macular hole. Am J Ophthalmol 1995;119:752.)