Purpose: To determine the safety and efficacy of corneal photovitrification (CPV), a corneal laser procedure, for vision improvement in patients with neovascular age-related macular degeneration (nAMD) and other retinal disorders involving central vision loss.

Design: Retrospective observational cohort study.

Methods: In this retrospective observational case series, 72 eyes of 54 patients received a single CPV treatment. Examinations included pre- and post-treatment (post-Tx) best-corrected distance visual acuity (BCDVA) and pre-Tx potential visual acuity (PVA).

Results: Safety - No clinically significant complications or serious adverse events were observed. Efficacy – Mean BCDVA improved significantly from 20/303 (1.18 logMAR, 26 letters) at baseline to 20/208 (1.02 logMAR, 34 letters) at 1m post-Tx (p = 0.000001) for a cohort of 57 eyes, improving to 20/198 (1.00 logMAR, 35 letters; 11.0 mean letters gained) at 12m (p = 0.0009) for a cohort of 29 eyes. Screening – Mean pre-Tx PVA gains correlated well with mean BCDVA improvements at 1m, 3m, 6m and 12m post-Tx.

Conclusions: Subject to a small sample size, the CPV corneal laser procedure is safe and efficacious for vision improvement in patients with nAMD and other retinal disorders involving central vision loss. The PVA test is useful for screening of candidate eyes for CPV treatment and for managing expectations.

This retrospective observational cohort study (registered with ClinicalTrials.gov NCT 04693702 on 5 January 2021) was completed in conformance with ethical principles of the World Medical Association Declaration of Helsinki. The study protocol (Pro00048890) was approved on 16 February 2021 by an institutional review board (Advarra. Aurora, Ontario, Canada). Informed consent, with a provision for release of medical records, was obtained from each patient. 72 eyes [53 nAMD, 9 dry AMD, 3 diabetic macular edema (DME), 3 macular hole, 2 myopic macular degeneration (MMD), and 2 branch retinal vein occlusion (BRVO)] of 54 patients [31F, 23M; mean (± SD) age: 79.1 (± 10.7) y] with retinal disorders with central vision loss received one treatment in each eye using the same device and protocol. Eyes were either pseudophakic or phakic with no visually significant cataract. All patient eyes had vision impairment, with mean ± SD best spectacle-corrected distance visual acuity (BCDVA) of 20/303 (1.18 ± 0.33 logMAR; 26.0 letters). At the time of CPV treatment, most (42 of 53) of the nAMD eyes were continuing to receive anti-VEGF injections using aflibercept; a few (5 of 53) eyes were continuing to receive ranibizumab injections; one was receiving bevacizumab injections and the remaining (5 of 53) eyes were no longer receiving injections. Eyes with nAMD had received anti-VEGF injections as needed, based on clinical examination and optical coherence tomography (OCT), over a mean ± SD period of 5.8 ± 3.3 years prior to CPV treatment.

Inclusion criteria included, in the eye to be treated, diagnosed retinal disorders involving central vision loss with moderate to profound BCDVA impairment (in the range of 20/63 to 20/2000). Exclusion criteria included previous corneal surgery and visually significant ocular disease other than AMD and other retinal disorders involving central vision loss.

Examinations on both treated and untreated eyes included slit-lamp biomicroscopy; subjective manifest refraction (SMR); BCDVA using ETDRS eye charts; and potential visual acuity (PVA)4 using Gonzalez-Markowitz charts (Precision Vision, Woodstock, IL) at 50 cm examination distance.

CPV treatments were completed using a Clear-K® Low Vision Aid System (Optimal Acuity Corporation, Austin, TX) to deliver pulsed laser energy simultaneously to the cornea in 4 spots of 0.5 mm diameter arranged symmetrically 90° apart and located on a 6.0 mm diameter ring centered on the pupillary centroid. Laser parameters included 2 µm wavelength, 150 ms pulse duration and 48 to 50 mJ energy per spot. Laser light was transmitted from the console through an optical fiber array terminated by a handpiece that docks onto a sapphire applanation window/suction ring (SAWSR) assembly mounted on the eye. Laser energy was delivered through the SAWSR onto the eye in order to provide a fixed location of treatment spots with epithelial protection (by the sapphire window acting as a heat sink) from thermal damage. Patients were reclined to a supine position, given a drop of topical anaesthetic in the eye to be treated, and then treated.

Statistical significances of paired outcomes were assessed by Wilcoxon signed rank tests. OD and OS logMAR values for correlated bilateral treatments were averaged for BCDVA at baseline and at each follow-up time in order to calculate statistical significances of post- vs. pre-Tx differences5. Statistical significances of the correlations between treatment efficacy and other variables were determined by shuffling the data and calculating the fraction of shuffled trials with correlation greater than the observed data.

Microsoft Excel and Igor Pro 8 functions were used for statistical analyses.

See ReadMe file and access spreadsheets.