Influences on Enhancement Rates in Laser Vision Correction

US Ophthalmic Review, 2016;9(2):107–9 DOI: https://doi.org/10.17925/USOR.2016.09.02.107

Abstract:

I ntroduction: The design of the study was to look consecutively at what are the prime influences on enhancements in laser vision correction related to the perioperative environment. Methods: A prospective consecutive series of 4,079 cases was reviewed from a single surgeon at a single surgical site. Patients were followed prospectively and were only included after at least two years of postoperative follow-up. Results: The series ranged in primary treatments of spherical equivalents (SE) from 0 to -12 diopters (D) with up to 4 D of cylinder. The preoperative average SE was -4.59±2.79 D and the cylinder average was -0.90±0.90 D. Uncorrected visual acuity (UCVA) prior to the enhancement was 0.63±0.23 (20/32) and post-enhancement was 0.99±0.20 (20/20). The top four influences on enhancements were presence of an opaque bubble layer (31.00%); dry eye disease (27.60%); history of ocular allergy (24.10%); and poor fixation (17.10%). Patients could have more than one of the above influences. Conclusions: Laser platforms, outcomes analysis, nomograms, and other influences will be discussed to help produce enhancement rates below 1.00%, which for this series was 0.71% overall.
Keywords: Laser in situ keratomeilusis (LASIK), enhancement rates, opaque bubble layer, dry eye disease, ocular allergy
Disclosure: Megan Stonecipher has nothing to disclose in relation to this article. Karl Stonecipher is a speaker, consultant and researcher for the following companies: Abbott Medical Optics, Alcon, Allergan, Alphaeon, Bausch and Lomb, Laser Defined Vision, Nidek, Physicians Protocol, Presbia, Refocus, Shire, TLC. No funding was received in the publication of this article.
Compliance with Ethics:All procedures were followed in accordance with the responsible committee on human experimentation and with the Helsinki Declaration of 1975 and subsequent revisions, and informed consent was received from the patient involved in this study. The design of the study was to look at the prime influences on enhancements in laser in situ keratomeilusis in a prospective fashion from one surgeon at one center with control of as many variables as possible.
Received: March 13, 2016 Accepted August 26, 2016
Correspondence: Megan Stonecipher, University of North Carolina at Chapel Hill, 1002 N. Church Street, Suite 101, Greensboro, North Carolina, 27401, US. E: mnstone@live.unc.edu
Open Access: This article is published under the Creative Commons Attribution Noncommercial License, which permits any noncommercial use, distribution, adaptation, and reproduction provided the original author(s) and source are given appropriate credit.

This research is primarily focused on the influences on enhancements in laser vision correction during the perioperative period. As surgeons we always strive to enhance technology while trying to improve outcomes. However, this study was a prospective look at what influences enhancement rates from a surgical technique, an intraoperative suite, or associated findings in patients. This study focused on associated influences in patients treated. The study group included a total of 4,079 consecutive cases, with 29 cases requiring enhancements (see Figure 1). The data for this study were prospectively collected from 2011 to 2013 and analyzed after at least two years of follow-up through 2015. Recent studies reported additional influences on myopic laser vision correction with the primary treatment being laser assisted in situ keratomeilusis (LASIK). In a study by Kruh et al., increased retreatment rates were seen with age >40 years old, initial manifest refraction spherical equivalent (MRSE) of -3.00 diopters (D) and astigmatism >1.00 D. In this particular report the enhancement rate was >5%.1 Kashani et al. have shown that retreatments of laser vision correction have favorable outcomes with respect to safety, predictability and efficacy.2 Our study primarily focused on perioperative variables and their influences on retreatments of laser vision correction.

Purpose
The design of the study was to look at the prime influences on enhancements in laser assisted in situ keratomeilusis (LASIK) in a prospective fashion from one surgeon at one center with control of as many variables as possible. Patients were followed for at least two years prior to being included in the series. Influences on perioperative outcomes were evaluated in a series of patients and the findings are reported.

Methods
There were 4,079 cases in total included in the prospective series, with 29 of those cases needing enhancements. The cases that were used for this study were collected prospectively from The Laser Eye Center©, Greensboro, between 2011 and 2013. All surgeries were performed by a single surgeon (Karl Gene Stonecipher). All flaps were created with either a WaveLight® FS200 Femtosecond Laser (Alcon, Novartis, Fort Worth, Texas, US) or IntraLase® FS Laser (AMO Abbott, Santa Ana, California, US). All of the treatments were performed with a WaveLight® Allegretto Wave® Eye-Q excimer 400 Hz laser (Alcon, Novartis, Fort Worth, TX, US) using a wavefront optimized treatment profile. Humidity was controlled between 45–50% and temperature was controlled between 65–70 degrees Fahrenheit using a Liebert® System for the operative suite (Emerson Power Network, Columbus, Ohio, US). Nomograms were created using Internet Based Refractive Analysis (Zubisoft, Switzerland).

Results
The series ranged in primary treatments of spherical equivalents (SE) from 0 to -12 D with up to 4 D of cylinder. The preoperative average SE was -4.59±2.79 D and the cylinder average was -0.90±0.90 D (Figure 2). Uncorrected visual acuity (UCVA) prior to the enhancement was 0.63±0.23 (20/32) and post-enhancement was 0.99±0.20 (20/20) (Figure 3). The overall enhancement rate for the group was 0.71%. The top four influences on enhancements were presence of an opaque bubble layer (OBL; 31.00%), dry eye disease (27.60%), history of ocular allergy (24.10%), and poor fixation (17.10%). Additional influences are presented in Figure 4.

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Keywords: Laser in situ keratomeilusis (LASIK), enhancement rates, opaque bubble layer, dry eye disease, ocular allergy