Selective Large-Area Retinal Pigment Epithelial Removal by Microsecond Laser in Preparation for Cell Therapy

PURPOSE: Cell therapy is a promising treatment for retinal pigment epithelium (RPE)-associated eye diseases such as age-related macular degeneration. Herein, selective microsecond laser irradiation targeting RPE cells was used for minimally invasive, large-area RPE removal in preparation for delivery of retinal cell therapeutics. METHODS: Ten rabbit eyes were exposed to laser pulses 8, 12, 16, and 20 µs in duration (wavelength, 532 nm; top-hat beam profile, 223 × 223 µm²). Post-irradiation retinal changes were assessed with fluorescein angiography (FA), indocyanine green angiography (ICGA), and optical coherence tomography (OCT). RPE viability was evaluated with an angiographic probit model. Following vitrectomy, a subretinal injection of balanced salt solution was performed over a lasered (maximum 13.6 mm(2)) and untreated control area. Bleb retinal detachment (bRD) morphology was then evaluated by intraoperative OCT. RESULTS: Within 1 hour after irradiation, laser lesions showed FA and ICGA leakage. OCT revealed that large-area laser damage was limited to the RPE. The angiographic median effective dose irradiation thresholds (ED(50)) were 45 µJ (90 mJ/cm(2)) at 8 µs, 52 µJ (104 mJ/cm(2)) at 12 µs, 59 µJ (118 mJ/cm(2)) at 16 µs, and 71 µJ (142 mJ/cm(2)) at 20 µs. Subretinal injection over the lasered area resulted in a controlled, shallow bRD rise, whereas control blebs were convex in shape, with less predictable spread. CONCLUSIONS: Large-area, laser-based removal of host RPE without visible photoreceptor damage is possible and facilitates surgical retinal detachment. TRANSLATIONAL RELEVANCE: Selective microsecond laser-based, large-area RPE removal prior to retinal cell therapy may reduce iatrogenic trauma.