Subtenon Autologous Platelet-Rich Plasma in Degenerative Retinal Diseases: A Prospective Pilot Study of Safety and...

Purpose: To evaluate the safety and feasibility of repeated subtenon administration of autologous platelet-rich plasma (PRP) in patients with degenerative retinal diseases and to explore preliminary, hypothesis-generating functional observations in retinitis pigmentosa (RP) and extensive macular atrophy with pseudodrusen-like appearance (EMAP). Methods: This prospective, open-label, uncontrolled pilot study included 13 patients (6 RP, 7 EMAP) who received three subtenon PRP injections (1.5 mL each) at baseline, Month 2, and Month 4, with follow-up through Month 6. The study was designed primarily to assess safety and feasibility and was not powered or intended to evaluate efficacy. The primary outcome was safety, including adverse events and intraocular pressure changes. Exploratory secondary outcomes included best-corrected visual acuity (BCVA, logMAR), visual field mean deviation (MD), and structural optical coherence tomography (OCT) parameters. Electrophysiological outcomes were analyzed descriptively due to incomplete paired data. Analyses were conducted within diagnostic groups, and no between-group comparisons were performed. Results: All 13 patients completed the study. No serious adverse events or permanent ocular morbidity were observed. Two transient and self-limited adverse events occurred (anterior uveitis and intraocular pressure elevation), both resolving without sequelae. In the overall cohort, BCVA remained stable without statistically significant change. In the RP subgroup, a small exploratory change in BCVA was observed (mean ΔlogMAR -0.09; nominal p = 0.048), corresponding to approximately 4-5 ETDRS letters; however, this finding was associated with wide confidence intervals and limited statistical power and should be interpreted cautiously. In the EMAP subgroup, functional stability was observed without evidence of consistent improvement. Visual field mean deviation and OCT findings were consistent with absence of short-term deterioration across available paired data. Electrophysiological outcomes showed no consistent directional change. Conclusions: Repeated subtenon PRP administration appeared feasible and well tolerated in this small, uncontrolled pilot cohort. Any observed functional changes are preliminary and hypothesis-generating only and do not establish efficacy. Larger, adequately powered controlled studies with standardized endpoints are required to determine the potential role of PRP in degenerative retinal diseases.