Autologous Neurosensory Retinal Flap Transplantation in a Porcine Model of Retinal Hole.

Abstract

Purpose: Autologous retinal transplantation has been successfully employed in the treatment of large and myopic macular holes that are refractory to standard surgical treatments. Patients transplanted with a peripheral neurosensory retinal graft have shown unexpected improvements in visual acuity. The study aims to investigate if neural integration of the graft takes place in a porcine model of retinal hole.

Design: Experimental animal study.

Subjects: Left eyes of 10 Danish landrace pigs.

Methods: The pigs underwent vitrectomy under general anesthesia, and a subretinal bleb was created within the visual streak on both sites of the optic disc. A retinal hole, approximately 1900 to 4000 microns in size, was cut temporally using a vitrector. A graft of matching size was harvested from the nasal retina. The graft was gently moved toward the retinal hole under perfluoro-n-octane and placed within it. Endolaser was applied around the donor site, and either air or oil tamponade was used. OCT and color fundus photography were performed 2 and 6 weeks after surgery. At the end of follow-up, the eyes were enucleated for histological examination, including immunohistochemical analysis with antibodies against retinal glial cells, photoreceptors, and inner retinal neurons.

Main outcome measures: The primary outcome measures were the morphology of the graft and the junctional area between the host and the graft.

Results: Retinal hole closure was achieved in 9 of 10 cases, with the graft remaining in situ in 6 cases. In 4 cases, OCT scans indicated preservation of the outer retinal layers, and in 2 of these cases, there was apparent integration with the adjacent host retina. Corresponding histology confirmed the preservation of the photoreceptor layer in 3 cases, but there was no evidence of graft integration with degeneration of the inner retina in all cases. The distance between the margins of the retinal hole decreased during follow-up, suggesting that the graft contracts and drags the surrounding retina toward the center.

Conclusions: The outer retina of a retinal graft can be preserved, while the inner retina degenerates. No evidence of neuroretinal integration of the graft was observed. The retinal graft serves as a scaffold, promoting the centripetal migration of the edges of the hole, resulting in closure of large retinal holes.

Financial disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.