The authors have reviewed 158 eyes with evolving or completed idiopathic macular holes. Observations of these patients suggest that prefoveal vitreous cortex contraction is probably the cause of idiopathic macular holes. The earliest sign of an impending macular hole (stage 1) appears to be the development of a yellow spot or halo associated with loss of the normal anatomic foveal depression. No vitreous separation is present. This may resolve or progress to a small, early macular hole (stage 2). This hole gradually enlarged to a diameter of approximately 485 micron. The vitreous usually remained attached or a vitreofoveal separation developed (stage 3). Some eyes had complete posterior vitreous separation (stage 4). The implications for surgical intervention are discussed. A prospective study should be undertaken to confirm these findings and to investigate the feasibility of vitrectomy intervention to peel the prefoveal vitreous cortex in eyes with a stage 1 lesion.