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Edge R, Argáez C. Laser Eye Surgery for Vision Correction: A Review of Clinical Effectiveness and Guidelines [Internet]. Ottawa (ON): Canadian Agency for Drugs and Technologies in Health; 2017 Jun 16.

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Laser Eye Surgery for Vision Correction: A Review of Clinical Effectiveness and Guidelines [Internet].

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Summary of Evidence

Quantity of Research Available

A total of 425 citations were identified in the literature search. Following screening of titles and abstracts, 421 citations were excluded and four potentially relevant reports from the electronic search were retrieved for full-text review. Eight potentially relevant publications were retrieved from the grey literature search. Of these potentially relevant articles, nine publications were excluded for examination of an irrelevant population, while three publications met the inclusion criteria and were included in this report. Appendix 1 describes the PRISMA flowchart of the study selection.

Additional references of potential interest are provided in Appendix 5.

Summary of Study Characteristics

One meta-analysis (MA),7 one health technology assessment (HTA),2 and one set of evidence-based guidelines1 were identified that met the selection criteria, although no identified studies fulfilled all criteria exactly. A summary of included study characteristics is provided in Appendix 2.

Study Design

The MA, published in 2017, examined the incidence of one adverse event outcome by comparative MA of large (minimum sample size of 1000) observational studies.7 The HTA was published in 2013 and examined the efficacy, effectiveness, and safety of refractive eye surgery through a systematic literature search of available evidence.2 The guidelines published by the American Academy of Ophthalmology in 2013 were designed as interpretations of the best identified evidence by committees of knowledgeable health professionals.1

Country of Origin

The MA was written by authors in the USA. The country of origin for included studies was not reported.7 The HTA was authored in Belgium and searched articles published in Dutch, English, French, and German.2 The included guidelines were published in the USA.1

Patient Population, Intervention, and Comparators

The MA did not specify inclusion of studies where patients had a new requirement for refractive correction or stable refraction, and it is the only identified study that directly compared corrective lenses to laser eye surgery. Studies included in the MA examined three different types of contact lenses, soft daily wear contact lenses, soft extended use contact lenses, and rigid gas permeable lenses. Different contact lenses were compared to each other, and compared to LASIK in this MA. Identified studies ranged from 1017 to 639 000 patients.7

The HTA was aimed at examining refractive eye surgery for adult patients with myopia, hyperopia and/or astigmatism. Studies that investigated other medical conditions such as cataract, presbyopia, glaucoma, corneal disease, and eye injuries were excluded from the HTA. Patient criteria did not specify a new requirement for refractive correction or patients with specific occupational vision requirements. Interventions of interest in the HTA were eyeglasses, contact lenses, laser refractive surgery, and intraocular lenses. The HTA included a systematic literature search to identify studies evaluating refractive eye surgery as compared to eyeglasses or contact lenses.2

The guidelines identified and included in this report define the patient population of interest as individuals beyond the amblyogenic age with refractive errors.1 Interventions of interest in these guidelines were eyeglasses, contact lenses, orthokeratology, and refractive surgery for myopia, astigmatism, presbyopia, or hyperopia.1

No studies were identified that specifically examined a patient population with a change in visual acuity requiring new or a change to current refractive correction, and no guidelines were identified with specific recommendations for first responder patient populations or patient populations with occupational requirements for visual acuity or firearms proficiency. No studies were identified that examined outcomes of any laser eye surgery to control patients receiving no treatment.


The MA was focused on examining the frequency of a single outcome, microbial keratitis infection.7 Microbial keratitis is the most serious risk of contact lens use and can lead to vision loss even if appropriately managed.1 When included studies provided culture-proven and presumed infection case numbers the analysis used presumed infection case numbers.7

The primary visual acuity outcomes searched for in the HTA were the need for glasses or contact lenses, the ratio or the mean postoperative uncorrected visual acuity (UCVA) to the mean preoperative best spectacle corrected visual acuity (BCVA), UCVA ≥20/20, and refraction within 0.5 diopters (D) of target refraction. Secondary visual acuity outcomes included in the search were UCVA ≥20/40, and refraction within 1 D of target refraction. The HTA also searched for quality of life and safety outcomes.2

The guidelines did not include a systematic literature search, however the formulated recommendations cite outcomes of corneal infection, acuity outcomes, quality of life, patient perceptions and expectations, side effects, and complications.1

Summary of Critical Appraisal

A tabulated summary of the critical appraisal of included literature is provided in Appendix 3.

The MA7 provided details on the systematic literature search used to identify included studies, however the authors did not present the results of the literature selection process. The MA provided information on data extraction methodology however this was not done in duplicate. A focused purpose and scope was a strength of the included MA, as was the provided discussion on the limitations of the study, and the lack of potential COI. The MA was limited by the identification of low quality study designs (case series and survey studies), lack of critical appraisal of these studies, and no assessment of statistical heterogeneity. The use of presumed infection case numbers from included studies is a potential source of bias.

The included HTA was comprehensive and had many strengths including an explicit scope and purpose, involvement of stakeholders and external experts, well described methodology, a literature search and selection methodology that included languages other than English with selection done in duplicate, and a described data extraction methodology. An economic assessment of laser eye surgery was also conducted in the included HTA. Limitations of the HTA included an undefined target audience, acknowledged potential COIs, and a lack of a specific discussion on the limitations of the HTA.2

The included guidelines had a broad focus that was defined along with a purpose and a target audience. Stakeholders and external experts were involved the development of the included guidelines. The recommendations are clearly identifiable, linked to supporting evidence, and graded. The guidelines also included some information on guideline implementation, patient assessment, and information on cost-effectiveness. Limitations of the guidelines include a literature search methodology that was reported to be detailed elsewhere and was unavailable for review, a lack of guideline development methodology, no specific discussion on the limitations of the guidelines, and acknowledged potential COIs.1

Summary of Findings

A summary of findings is also provided in Appendix 4.

What is the clinical effectiveness of laser eye surgery in adults newly requiring vision correction and those with unstable visual acuity requiring a change to current refractive correction?

The included MA did not define the patient population as having a new requirement for vision correction, as having stable vision, or if it was a mixed patient population. The analysis presents data supporting a less frequent occurrence over 10 years of presumed microbial keratitis in patients who received LASIK as compared to patients who wear any examined contact lens type. Over five years patients wearing soft contact lenses and daily wear contact lenses also experienced a greater frequency than LASIK patients, and only soft contact lens wearers would experience a greater frequency of microbial keratitis than LASIK patients in the first year following surgery. Both patients wearing daily wear soft contacts and patients wearing rigid gas permeable contact lenses experienced a statistically significant less frequent infection occurrence (P < 0.05) during the first year following LASIK. These findings remain relatively unchanged when a 10% retreatment or enhancement rate for LASIK patients is accounted for.7

The HTA from 2013 conducted a systematic literature search and did not find any systematic reviews or RCTs that evaluated refractive eye surgery as compared to eyeglasses or contact lenses. The HTA also did not identify studies that reported outcomes of dependence on corrective lenses. The HTA noted safety considerations that flap complications can occur with LASEK and LASIK, while PRK and LASEK can be associated with more pain. Dry eyes was reported as the leading adverse event associated with LASIK however the symptoms resolve six months following surgery.2

What are the evidence-based guidelines associated with laser vision correction in first responders or in persons required to maintain a high visual acuity?

The identified guidelines did not formulate recommendations specific to first responders or persons required to maintain high visual acuity. Relevant recommendations and statements from the included guidelines are quoted and provided in Appendix 4, Table 7. One strong recommendation based upon moderate evidence included information on patient selection for refractive surgery that did not include criteria for refractive stability, however a list of refractive surgery contraindications included unstable refraction.


No evidence directly addressing the selection criteria was identified for this review. Evidence from the identified MA may be from an irrelevant or mixed population as the patient population was not sufficiently defined.

Copyright © 2017 Canadian Agency for Drugs and Technologies in Health.

The copy right and other intellectual property rights in this document are owned by CADTH and its licensors. These rights are protected by the Canadian Copyright Act and other national and international laws and agreements. Users are permitted to make copies of this document for non-commercial purposes only, provided it is not modified when reproduced and appropriate credit is given to CADTH and its licensors.

Except where otherwise noted, this work is distributed under the terms of a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND), a copy of which is available at

Bookshelf ID: NBK488015


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