Three-Dimensional Optical Coherence Tomography Imaging of Retinal Sheet Implants in Live Rats

Abstract

Purpose: : To obtain three-dimensional images from retinal transplants in live animals and evaluate the placement and structural quality of the transplants.

Methods: : Donor retinal sheets were isolated from E19 fetuses of transgenic rats expressing human alkaline phosphatase (hPAP) as a marker, and transplanted to the subretinal space of 24 - 56 d old S334ter-3 rat recipients with fast retinal degeneration. Forty-one rats were imaged 6 - 67 d after transplant surgery, at the age of 36 to 107 d, using a Fourier domain optical coherence tomography (FDOCT) system, with an axial resolution of 3.5 micron. The CCD A-line integration time was set at 200 µs for better visualization of degenerated retina. After targeting the transplant area, 198 consecutive slices were scanned. From these scans, 3D-projection images and movies of the retinal transplant area were computed.

Results: : Transplants could easily be identified. OCT scans also showed whether the transplants had been correctly placed into the subretinal space, and whether there had been damage to the RPE or choroid during implantation. OCT indicated the laminar structure of the implants. Three-dimensional projections showed the transplant position in the retina in relation to the optic disc. Transplants were identified histologically by hPAP staining.

Conclusions: : Optical Coherence Tomography is an excellent tool to image retinal layers in a live rat. This is important to assess the transplant success early after surgery. This procedure helps to evaluate the placement and layering of the implants in the living eye.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: non-clinical • transplantation