Epithelium-on photorefractive intrastromal cross-linking (PiXL) for reduction of low myopia

Abstract

PurposeTo report the 9–12-month outcomes of a novel procedure for reduction of low myopia through epithelium-on photorefractive intrastromal cross-linking (PiXL) with customized control of topographic distribution of ultraviolet (UV)-fluence.MethodMyopic patients with normal (non-ectatic) corneas underwent the PiXL procedure for reduction of low myopia. PiXL treatments were delivered through selective application of UVA light based on the refractive error of each patient. Clinical evaluation included safety (corrected distance visual acuity, endothelial cell count, central corneal thickness, anterior ocular health) and efficacy (uncorrected distance visual acuity, manifest refraction, K-mean) examinations. In addition, a patient satisfaction survey was conducted at 9 months post-procedure to evaluate patients’ subjective experience with the procedure.ResultsFourteen myopic eyes (mean manifest refraction spherical equivalent −1.62±0.6D; range −0.75 to −2.65D) of 8 subjects (mean age 30 years old; range 24–51 years old) were enrolled in the study. At 12 months post-procedure, a mean manifest refraction spherical equivalent reduction of 0.72±0.43D (P<0.001) was observed, with a corresponding gain in uncorrected visual acuity of 0.25 logMAR and mean K-mean flattening of 0.47±0.46D. All patients achieved best corrected visual acuity of 20/20 or better from 1 month onward. There were no cases of ocular infection or secondary changes to the crystalline lens and retina due to UV exposure, while transient corneal haze subsided gradually.ConclusionThe epithelium-on PiXL procedure was safe and effective in reducing myopic refractive error in this study with up to 12 months follow-up. Early results of this novel application of collagen cross-linking are encouraging but longer-term data in larger studies are required.PrecisThis paper serves to introduce and report the early clinical results of epithelium-on PiXL, a novel application of cornea cross-linking, in reducing low myopia in Asian eyes, which are under-represented in studies of similar design.

A prospective evaluation of photorefractive intrastromal cross‐linking for the treatment of low‐grade myopia

“…Early clinical results support the ability of PiXL to predictably flatten a myopic cornea without significant changes to the endothelial cell count (ECC) or corneal clarity Nordstrom et al 2017). Lim et al (2017) followed eight subjects after PiXL in healthy myopic eyes, reporting a mean improvement of 0.25 LogMAR (2.5 Snellen lines) in uncorrected distance visual acuity at 1-year follow-up.…”

“…Lim et al. () followed eight subjects after PiXL in healthy myopic eyes, reporting a mean improvement of 0.25 LogMAR (2.5 Snellen lines) in uncorrected distance visual acuity at 1‐year follow‐up.…”

A Review of Corneal Collagen Cross-linking – Current Trends in Practice Applications

“…Kanellopoulos first described the preliminary results for low myopic correction [ 98 ]. Lim et al reported on the results of PiXL for the treatment of low myopia in a cohort of 14 eyes with a 1 year followup [ 99 ]. High fluence UV-A irradiation ranging from 10-15 J/cm was delivered over a 4.5mm central zone.…”

Clinical presentation following photorefractive intrastromal cross-linking for myopic correction

“…demonstrated the results in a cohort of 14 eyes with a mean reduction in spherical equivalent of 0.72 ± 0.43D using the epithelium on approach. [ 2 ] Elling et al . demonstrated superior visual outcomes in 26 eyes undergoing PiXL following epithelial debridement.…”