PRK Enhancement for Residual Refractive Error After Primary PRK: A Retrospective Study

Majid Moshirfar; Alex Villarreal; Andrew C Thomson; William B West Jr; Shannon E McCabe; Eduardo Quinonez Zanabria; Derrick B Graham; Yasmyne C Ronquillo; Phillip C Hoopes Sr

doi:10.1007/s40123-021-00331-8

PRK Enhancement for Residual Refractive Error After Primary PRK: A Retrospective Study

Ophthalmol Ther. 2021 Mar;10(1):175-185. doi: 10.1007/s40123-021-00331-8. Epub 2021 Jan 30.

Authors

Affiliations

¹ Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA. cornea2020@me.com.
² Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA. cornea2020@me.com.
³ Utah Lions Eye Bank, Murray, UT, USA. cornea2020@me.com.
⁴ McGovern Medical School, The University of Texas Health Science Center, Houston, TX, USA.
⁵ University of Utah School of Medicine, Salt Lake City, UT, USA.
⁶ Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA.
⁷ Mission Hills Eye Center, Pleasant Hill, CA, USA.
⁸ University of Arizona College of Medicine, Tucson, AZ, USA.
⁹ Texas Tech University Health Sciences Center School of Medicine, Lubbock, TX, USA.

Abstract

Introduction: The efficacy and safety of photorefractive keratectomy (PRK) has been well documented, but outcomes of PRK enhancement following PRK remain understudied. This study aimed to evaluate the safety, efficacy, and predictability of PRK enhancement in patients with residual refractive error after primary PRK and compare these results to prior studies as well as Food and Drug Administration (FDA) safety and efficacy clinical endpoints.

Methods: This non-randomized, retrospective chart analysis included eyes with a history of PRK that underwent PRK enhancement at a single center. Post-enhancement data were documented at 3-month and 1-year visits. Patient characteristics between the study group and a control group who underwent primary PRK only were compared. Safety and efficacy measures included change in uncorrected distance visual acuity (UDVA), change in corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), amount of induced astigmatism, and presence of serious adverse events.

Results: A total of 188 eyes from 141 patients were included. When compared to the control group, women underwent PRK enhancement at a higher rate than men (P = 0.004). The group undergoing PRK enhancement had a higher sphere (P = 0.013) and spherical equivalent (P = 0.004) than the control group at the time of primary PRK. MRSE was reduced to - 0.97 ± 0.72 D (- 2.25 to + 2.13 D) from pre-enhancement values of - 0.98 ± 0.66 D (- 2.75 to + 1.75 D) and stable over 12-month visits with 86% and 98% of eyes within ± 0.50 D and ± 1.00 D of target, respectively. UDVA of 20/20 or better was achieved in 75% of eyes. The UDVA of 75% of eyes remained the same or improved by 1 or more Snellen lines compared with pre-enhancement CDVA.

Conclusion: Our results demonstrate that, when compared with previous studies, modern PRK enhancement after PRK has improved visual acuity and refractive outcomes. Though PRK enhancement is not an FDA approved procedure, we show that it meets or exceeds the FDA criteria for the correction of refractive error.

Keywords: Enhancement; PRK enhancement; Photorefractive keratectomy.