[Ultrastructural findings of epimacular membrane and detached posterior hyaloid in vitreomacular traction syndrome].

PURPOSE: Vitreomacular traction syndrome is characterized by an incomplete posterior vitreous detachment and by the cortical vitreous remaining attached to the macula. In certain case epimacular membrane is clinically well defined. We studied the electron microscopic features of epiretinal tissue and posterior hyaloid removed from the posterior pole.

MATERIAL AND

METHODS

[corrected] Six epimacular membranes were removed during a pars plana vitrectomy, placed in 2.5% glutaraldehyde solution, embedded in Epoxy resin, and examined in a transmission electron microscope. The detached posterior hyaloid was removed and analyzed separately in two cases.

RESULTS

The analysis disclosed five morphologically cell types. Fibrous astrocytes were predominant in five cases. Other cell types were less frequent and were identified as fibroblasts, macrophages and myofibroblasts. In one case epithelial-like cell type was predominant. The stroma was mainly composed of a thin layer of 15-nm diameter collagen evoking a vitreous origin. Internal limiting membrane was present in one case only. Detached posterior hyaloid was constituted by the same cellular constituents on thin layer of vitreous collagen.

DISCUSSION: The cellular proliferation is principally constituted by fibrous astrocyte and occurs on the inner surface of cortical vitreous. Some glial cells seem to present an epithelial differentiation.

CONCLUSION

The attached and detached posterior hyaloid in vitreomacular traction syndrome is the place of glial cells migration and proliferation.