Using transmission electron microscopy (TEM), we studied the ultrastructures of rapidly proliferating preretinal membranes of young patients with very extensive ischemic proliferative diabetic retinopathy and diabetes with uncontrollable blood sugar level.

Nine cases of preretinal membranes were obtained from six eyes of five patients with rapidly progressed proliferative diabetic retinopathy (mean age, 35 years) during vitrectomy. We obtained each preretinal membrane bimanually as one single sheet membrane using intraocular scissors and forceps. Each tissue was fixed in 3% glutaraldehyde in the operating room. All specimens were prepared and studied using TEM.

The preretinal membranes were composed of blood vessels and some interstitial cells. The blood vessels within the preretinal membranes varied in developmental stages, from the immature stage to the mature stage. The blood vessels were highly active, in that primitive cells showed a large nucleus and prominent chromatin clumping with abundant cytoplasm. Highly active fibroblast-like cells were also noted.

We observed highly active angiogenesis in preretinal membranes, which rapidly proliferated in cases of severe retinal ischemia in young diabetes patients. This is the first report of such a finding, which may help to explain the poor prognosis of this disease modality.