DOI: 10.5061/dryad.m905qfv2r
title: Corneal Laser Procedure for safety and efficacy in vision improvement

description: 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.
description: 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.
description: See ReadMe file and access spreadsheets.