Purpose: To compare the ultrastructural features of excised tissue removed during surgery for idiopathic macular holes with the preoperative stage of the macular hole.
Methods: Twelve consecutive patients with a unilateral idiopathic macular hole underwent vitrectomy with surgical removal of the internal limiting membrane of the retina and epiretinal tissue overlying and surrounding the hole. The excised specimens were evaluated with transmission electron microscopy, and findings were compared with the preoperative stage of the macular hole according to the classification of Gass.
Results: Surgery was performed on 12 eyes of 12 patients with stage 2, 3, or 4 macular holes. Internal limiting membrane was present in 11 of 12 specimens. Tissue from one of two eyes with stage 2 holes showed cellular elements enmeshed in cortical vitreous. Tissue from four of seven eyes with stage 3 holes and three of three eyes with stage 4 holes had cellular proliferation on the internal limiting membrane. Cells with myofibroblastic differentiation were present in five of the eight cellular proliferations.
Conclusion: Our results support the clinical stages of idiopathic macular holes described by Gass. Idiopathic macular holes appear to form from contraction of the prefoveal vitreous, and the hole enlarges because of contraction of myofibroblasts on the inner surface of the internal limiting membrane. On the basis of the mechanical mechanisms of idiopathic macular hole formation, removal of the internal limiting membrane and adherent epiretinal tissue surrounding and overlying the macular hole is a reasonable surgical approach to close idiopathic macular holes.