Human neural retinal transplantation

PURPOSE. A pilot Study of human neural retinal transplantation was undertak en to investigate three major issues: whether a safe surgical procedure cou ld be devised for transplantation of neural retinal tissue into the subreti nal space, whether the transplant would be accepted in the subretinal space , and whether an improvement in vision could be achieved. METHODS. Eight patients with bare light perception (LP) vision due to retin itis pigmentosa (RP) and one patient with bare LP vision due to advanced ne ovascular age-related macular degeneration (AMD) received subretinal transp lants of human fetal retinal microaggregate suspensions without postoperati ve systemic immunosuppression. The patient with AMD also received a fetal r etinal sheet transplant. The ages of the patients ranged from 31 to 94 year s (median, 55 years). The pre- and postoperative evaluations included visua l function testing, detailed fundus examinations, fundus photography, fluor escein angiography. macular perimetry using a scanning laser ophthalmoscope (SLO), and full field and focal electroretinograms (ERGs). RESULTS. Three of the eight RP patients demonstrated possible improved ligh t sensitivity during the initial months of follow-up. However, visual impro vement disappeared between 3 and 13 months of follow-up. After transplantat ion, no subject showed any changes in the ERG recordings or SLO macular per imetry relative to their preoperative baseline. No patient experienced a re tinal detachment, infection, or extensive bleeding. None of the patients de veloped retinal vasculitis or intraocular inflammation. In one RP patient, fluorescein angiography and fundus photography documented the formation and maturation of new host retinal vessels in the area of the transplant. CONCLUSIONS. Transplantation of fetal retinal photoreceptor suspensions int o the subretinal space was achieved safely in nine subjects. Although a def inite positive effect on visual function could not be demonstrated, the app arent high tolerance for graft tissue is promising fur future efforts in th e field of neural retinal transplantation.