Transepithelial photorefractive intrastromal corneal crosslinking versus photorefractive keratectomy in low myopia

Abstract

Purpose: To compare transepithelial (TE) photorefractive intrastromal corneal cross-linking (PiXL) and photorefractive keratectomy (PRK) in low myopia. Setting: Monocentric study conducted in France (Purpan Hospital, Toulouse) Design: Prospective, intraindividual ethics committee-approved, comparative nonrandomized study. Methods: Myopic patients with manifest refraction spherical equivalent (MRSE) of -1.00 to -2.50 diopters (D), and cylindrical component plano to -0.75 D were included. Dominant eye underwent PRK, and non-dominant eye TE-PiXL procedure with riboflavin (Paracel ® Part 1 & 2, Avedro Inc., Waltham, MS, USA), 30 mW/cm 2 pulsed UVA irradiation centered on pupil (Mosaic™ System,Avedro Inc., Waltham, MS, USA) for 16 minutes and 40 seconds and supplemental oxygen delivery mask. The primary outcome measure was the change in MRSE. Other outcome measures were uncorrected and corrected distance visual acuity (UDVA and CDVA), mean keratometry (Km), and endothelial cell count (ECC) with a 6month follow-up. Adverse events were also assessed. Results: Nineteen patients were included. At 6 months, mean MRSE decreased by 0.72 ± 0.42 D in TE-PiXL eyes and by 1.35 ± 0.46 D in PRK eyes (P <.001). The mean change in UDVA was -0.35 ± 0.21 LogMAR in TE-PiXL eyes and -0.66 ± 0.19 LogMAR in PRK eyes (P <.001). No complications were reported. ECC and CDVA were statistically unchanged. Conclusion: PRK provided better visual and refractive outcomes than TE-PiXL. TE-PiXL however demonstrated the potential refractive effect of corneal cross-linking but with a limited magnitude of myopic correction to this point.

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

“…Apparently, removing the epithelium augments the treatment effect sufficiently for room air treatment, whereas our present findings indicate that the effect is barely measurable with epi-on treatment in room air. A study published in 2019 from El-Hout et al showed an effect of 0.72 AE 0.42 D with epi-on PiXL in a high oxygen environment at 6 months (El Hout et al 2019). The present study is the first to present 12-month data on epi-on PiXL for myopia in a high oxygen environment.…”

“…The fact that we terminated the inclusion into two of the three treatments is a definite limitation of this study. However, these decisions were necessary and we still feel that our present findings, together with what has previously been published in this field (Kanellopoulos 2014;Elling et al 2018;El Hout et al 2019), are interesting enough to justify further studies on PiXL treatment for low-grade myopia.…”

“…; El Hout et al. ), are interesting enough to justify further studies on PiXL treatment for low‐grade myopia.…”

“…showed an effect of 0.72 ± 0.42 D with epi‐on PiXL in a high oxygen environment at 6 months (El Hout et al. ). The present study is the first to present 12‐month data on epi‐on PiXL for myopia in a high oxygen environment.…”

Accelerated, Pulsed Collagen Cross-Linking versus the Dresden Protocol in Keratoconus: A Case Series

“…Pulsing the UV light theoretically increases the oxygen concentration by slowing the rate of oxygen consumption and restarts the photodynamic type II reaction achieving an additional oxygen concentration for crosslinking of collagen molecules [8]. El Hout et al [31] introduced a custom-made oxygen delivery mask connected to an oxygen wall outlet with a flow meter and bubble humidifier in order to achieve higher oxygen concentrations in the cornea with promising results. DOI: 10.1159/000505598…”