Retinal transplants evaluated by optical coherence tomography in photoreceptor degenerate rats

Optical coherence tomography (OCT), a non-invasive method, was used for qualitative assessment of fetal retinal sheet transplants by non-invasive imaging. Rhodopsin-mutant S334ter-line-3 rats with fast retinal degeneration (28-37-day old) were transplanted with fetal retinal sheets from embryonic day (E) 18-19 pigmented normal rats. Retinal thickness measurements from transplanted (n = 51), no surgery control (n = 8), and normal pigmented rat eyes (n = 6) were obtained using a Zeiss stratus OCT-3 scanning instrument. Frozen retinal sections were stained with hematoxylin/eosin. S334ter-line-3 rats showed significant reduction in OCT retinal thickness (p<0.001) compared to normal pigmented rats at the age of 21 days. In 62% of the transplanted rats, OCT scanning revealed the presence of a subretinal graft, which was confirmed by subsequent histology. Retinal thickness in the transplant area was significantly increased compared to the area outside the transplant and to non-transplanted eyes (p<0.001). While most of the transplants with single-band OCT images (87%) had rosetted transplants, a considerable proportion of transplants having a multi-band OCT image were found to have well-laminated areas in the graft after histological evaluation. Following retinal transplantation in rodents, OCT imaging data correlated mostly with transplant morphology. OCT is a useful technique for in vivo screening and evaluation of retinal transplants. This technique determines surgical outcomes at a much earlier stage.