Background: Transplantation of autologous iris pigment epithelium (IPE) into the subretinal space has been suggested as one approach for the treatment of age-related macular degeneration, as well as for other conditions in which loss of retinal pigment epithelium (RPE) occurs. Surgical removal of choroidal neovascular membranes is associated with traumatic loss of the RPE cell layer, disruption of the integrity of the photoreceptor-RPE complex, and limited visual outcome.
Objective: To examine whether IPE cells can substitute for RPE cells to be transplanted to the subretinal space of patients with either RPE degenerative disease or traumatic loss of the RPE cell layer after subretinal surgery.
Methods: Autologous IPE cells were transplanted to the subretinal space in 20 consecutive patients undergoing removal of subretinal fibrovascular membranes using pars plana vitrectomy. Autologous IPE cells were harvested by iridectomy, isolated, and transplanted directly to the subretinal spaces. Transplants were evaluated for 6 to 11 months by funduscopy, fluorescein angiography, and scanning laser ophthalmoscopic (SLO) microperimetry.
Results: For the entire follow-up period, no evidence of any immunologic response was observed. Revisional surgery was necessary in 3 patients because of complications (rhegmatogenous retinal detachment [n = 1]; proliferative vitreoretinopathy [n = 1]; and macular pucker [n = 1]); 1 patient did not receive IPE cells. Five of 19 phakic eyes underwent cataract surgery; in 1 case this was combined with the vitrectomy. Five patients showed improved visual acuity of 3 to 4 lines, 13 patients had stable visual acuity (+/-2 lines), and 2 patients had reduced visual acuity of 6 lines.
Conclusions: In this pilot study, the transplantation of autologous IPE cells was done as an addition to conventional surgical excision of choroidal neovascular membranes. Transplanted cells were well tolerated in the subretinal space and did not adversely affect the function of the photoreceptors, since improvement or stable visual acuity was observed in 18 patients after IPE transplantation. These results suggest that autologous IPE cells may be used as a substitute for autologous RPE cells to transplant to the subretinal space to treat age-related macular degeneration.