Ultrastructural analyses of internal limiting membrane excised from highly myopic eyes with myopic traction maculopathy.

Purpose: To evaluate the ultrastructure of the internal limiting membranes (ILMs) excised during vitrectomy from highly myopic eyes with myopic traction maculopathy (MTM). The clinical findings before and after the vitrectomy were compared.

Methods: Seven eyes of 7 patients with macular retinoschisis were studied. Four of these eyes also had a foveal detachment but without a retinal break. All the eyes underwent vitrectomy with the creation of a posterior vitreous detachment and ILM peeling. The excised ILMs were examined by transmission electron microscopy (TEM).

Results: The retinas were reattached in all eyes after the vitrectomy. No retinal breaks including macular holes were identified intraoperatively. Transmission electron microscopy showed glial cells in 4 eyes, retinal pigment epithelium-like cells in 4 eyes, and myofibroblast-like cells in 4 eyes on the excised ILMs. A newly produced basement membrane appeared to merge with the ILM in 5 eyes. Thick collagen was seen in 2 eyes, and fibrous long-spacing collagen in the newly synthesized collagen fibers was seen in 3 eyes. The cellular components of the glial cells appeared to have migrated through the thinner parts of the retina or through a defect of the ILM in 2 eyes.

Conclusions: Cells that migrate onto the surface of the ILM synthesize new collagen, which can create tangential traction. This may explain the success of vitrectomy with ILM peeling in treating MTM in highly myopic eyes.