Histologic findings following retinal pigment epithelium removal using 8 microsecond laser pulses

In the treatment of various retinal pigment epithelium (RPE) related retinal diseases, selective retina therapy (SRT) is highly demanded, as SRT intends to selectively damage the RPE while sparing the neurosensory retina (NSR) and the choroid. A gentle method for removing diseased host RPE cells is still missing regarding RPE stem cell therapy. Cell therapeutics for age-related macular degeneration are often implanted regardless of host RPE status in the target zone, which may result in RPE multilayering. Here, we study a novel laser for selective large-area RPE removal without damaging the surrounding tissue prior to RPE implantation to promote subretinal integration. Therefore, pigmented rabbit eyes were exposed to laser pulses of 8 μs in duration (wavelength, 532 nm; top-hat beam profile, 223 × 223 μm2). Postirradiation retinal changes were assessed with color fundus photography, fluorescein angiography, indocyanine green angiography, and optical coherence tomography (OCT). Here we present the histological outcome of four animals after laser treatment. Following euthanization, the eyes of the animals were processed for histology, sectioned in 5 μm paraffin sections and stained with hematoxylin and eosin. Particular emphasis was given to an OCT vs light microscopy comparison. Our results reveal that RPE can be removed selectively using laser pulses of 8 µs duration in the green spectral range without damaging the NSR. Therefore, this regime proves to be applicable in the sense of SRT.