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The Cochrane Database of Systematic... Jul 2018Recurrent corneal erosion is a common cause of disabling ocular symptoms and predisposes the cornea to infection. It may follow corneal trauma. Measures to prevent the... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Recurrent corneal erosion is a common cause of disabling ocular symptoms and predisposes the cornea to infection. It may follow corneal trauma. Measures to prevent the development of recurrent corneal erosion following corneal trauma have not been firmly established. Once recurrent corneal erosion develops, simple medical therapy (standard treatment) may lead to resolution of the episode. However, some people continue to suffer when such therapy fails and repeated episodes of erosion develop. A number of treatment and prophylactic options are then available but there is no agreement as to the best option. This review version is an update to the original version published in 2007 and a previous update published in 2012.
OBJECTIVES
To assess the effectiveness and adverse effects of regimens for the prophylaxis of further recurrent corneal erosion episodes, the treatment of recurrent corneal erosion and prophylaxis of the development of recurrent corneal erosion following trauma.
SEARCH METHODS
We searched CENTRAL, which contains the Cochrane Eyes and Vision Trials Register; MEDLINE; Embase; LILACS; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 14 December 2017.
SELECTION CRITERIA
We included randomised and quasi-randomised trials that compared a prophylactic or treatment regimen with another prophylaxis/treatment or no prophylaxis/treatment for people with recurrent corneal erosion.
DATA COLLECTION AND ANALYSIS
We used standard methods expected by Cochrane. Two authors independently screened search results, extracted data and assessed risk of bias in the included studies using the Cochrane tool for assessing risk of bias. We considered the following outcome measures: resolution of symptoms after treatment; recurrence after complete or partial resolution; symptoms (pain); adverse effects (corneal haze, astigmatism). We graded the certainty of the evidence using GRADE for the three most clinically relevant comparisons.
MAIN RESULTS
We included eight randomised and two quasi-randomised controlled trials in the review, encompassing 505 participants. Seven studies were from Europe (Germany, Sweden and the UK), two from East Asia (Hong Kong and Japan) and one from Australia. Nine of the studies examined treatments for episodes of recurrent corneal erosions and one study considered prophylaxis to prevent development of recurrent corneal erosions after injury. Two of the nine treatment studies also enrolled participants in a study of prophylaxis to prevent further episodes of recurrent corneal erosions. The studies were poorly reported; we judged only one study low risk of bias on all domains.Two studies compared therapeutic contact lens with topical lubrication but one of these studies was published over 30 years ago and used a therapeutic contact lens that is no longer in common use. The more recent study was a two-centre UK study with 29 participants. It provided low-certainty evidence on resolution of symptoms after treatment with similar number of participants in both groups experiencing resolution of symptoms at four months (risk ratio (RR) 0.97, 95% confidence interval (CI) 0.62 to 1.53). There was very low-certainty evidence on recurrence after partial or total resolution at seven months' follow-up (RR 1.07, 95% CI 0.07 to 15.54). There was no evidence of an important difference in pain score (score of 3 in the contact lens group and score of 2 in the topical lubrication group, low-certainty evidence) and no adverse effects were reported. The older study, using a contact lens no longer in common use, found an increased risk of pain and complications with the contact lens compared with hypromellose drops and paraffin ointment at night.A single-centre, Australian study, with 33 participants, provided low-certainty evidence of an increased risk of recurrence with phototherapeutic keratectomy compared with alcohol delamination but with wide confidence intervals, compatible with increased or decreased risk (RR 1.27, 95% CI 0.48 to 3.37). Time to recurrence was similar in both groups (6.5 and 6 months, low-certainty evidence). On average people receiving phototherapeutic keratectomy reported less pain but confidence intervals included no difference or greater pain (mean difference (MD) -0.70, 95% CI -2.23 to 0.83, low-certainty evidence). No adverse effects were reported.A 48-participant study in Hong Kong found recurrences were less common in people given diamond burr superficial keratectomy after epithelial debridement compared with sham diamond burr treatment after epithelial debridement (RR 0.07, 95% CI 0.01 to 0.50, moderate-certainty evidence). The study did not report pain scores but adverse effects such as corneal haze (RR 0.92, 95% CI 0.06 to 13.87, low-certainty evidence) and astigmatism (0.88 versus 0.44 dioptres, moderate-certainty evidence) were similar between the groups.A study comparing transepithelial versus subepithelial excimer laser ablation in 100 people found low-certainty evidence of a small increased risk of recurrence of corneal erosion at one-year follow-up in people given the transepithelial compared with subepithelial technique, however, the confidence intervals were wide and compatible with increased or decreased risk (RR 1.20, 95% CI 0.58 to 2.48, low-certainty evidence). Other outcomes were not reported.Other treatment comparisons included in this review were only addressed by studies published two decades or more ago. The results of these studies were inconclusive: excimer laser ablation (after epithelial debridement) versus no excimer laser ablation (after epithelial debridement), epithelial debridement versus anterior stromal puncture, anterior stromal puncture versus therapeutic contact lens, oral oxytetracycline and topical prednisolone (in addition to 'standard therapy') versus oral oxytetracycline (in addition to 'standard therapy') versus 'standard therapy'.
AUTHORS' CONCLUSIONS
Well-designed, masked, randomised controlled trials using standardised methods are needed to establish the benefits of new and existing prophylactic and treatment regimes for recurrent corneal erosion. Studies included in this review have been of insufficient size and quality to provide firm evidence to inform the development of management guidelines. International consensus is also needed to progress research efforts towards evaluation of the major effective treatments for recurrent corneal erosions.
Topics: Anti-Bacterial Agents; Contact Lenses; Corneal Diseases; Corneal Injuries; Debridement; Eye Infections; Glucocorticoids; Humans; Keratectomy; Lubricant Eye Drops; Pain Measurement; Prednisolone; Randomized Controlled Trials as Topic; Recurrence; Secondary Prevention; Tetracycline
PubMed: 29985545
DOI: 10.1002/14651858.CD001861.pub4 -
Scientific Reports May 2018Congenital ptosis may be associated with abnormalities of visual development and function, including amblyopia, strabismus and refractive errors. However, the prevalence... (Meta-Analysis)
Meta-Analysis
Congenital ptosis may be associated with abnormalities of visual development and function, including amblyopia, strabismus and refractive errors. However, the prevalence estimates of these abnormalities vary widely. We performed a systematic review and meta-analysis to estimate the prevalence of amblyopia, strabismus and refractive errors in congenital ptosis. Cochrane, Pubmed, Medline, Embase, and Web of Science were searched by July 2017. We used random/fixed effects models based on a proportion approach to estimate the prevalence. Heterogeneity would be considered signifcant if the p values less than 0.1 and/or I greater than 50%. Subgroup analyses, meta-regression analyses and sensitivity analyses were utilized to explore the potential sources of it. A total of 24 studies selected from 3,633 references were included. The highest prevalence was revealed for myopia with 30.2% (95%CI 3.0-69.8%), followed by 22.7% (95%CI 18.5-27.8%) for amblyopia, 22.2% (95%CI 7.8-63.1%) for astigmatism, 19.6% (95%CI 16.5-23.2%) for strabismus, 17.3% (95% CI 13.1-22.9%) for anisometropia and 4.0% for hyperopia (95%CI 1.8-7.1%). Significant heterogeneity was identified across most estimates. Our findings suggest that amblyopia, strabismus and refractive errors in congenital ptosis are present in much higher percentage. This study highlights the importance of early diagnosis and timely treatment of patients with congenital ptosis.
Topics: Amblyopia; Anisometropia; Astigmatism; Blepharoptosis; Humans; Hyperopia; Myopia; Prevalence; Refractive Errors; Strabismus; Visual Acuity
PubMed: 29844360
DOI: 10.1038/s41598-018-26671-3 -
Clinical & Experimental Optometry Jul 2018Uncorrected refractive error is an avoidable cause of visual impairment which affects children in India. The objective of this review is to estimate the prevalence of...
Uncorrected refractive error is an avoidable cause of visual impairment which affects children in India. The objective of this review is to estimate the prevalence of refractive errors in children ≤ 15 years of age. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in this review. A detailed literature search was performed to include all population and school-based studies published from India between January 1990 and January 2017, using the Cochrane Library, Medline and Embase. The quality of the included studies was assessed based on a critical appraisal tool developed for systematic reviews of prevalence studies. Four population-based studies and eight school-based studies were included. The overall prevalence of refractive error per 100 children was 8.0 (CI: 7.4-8.1) and in schools it was 10.8 (CI: 10.5-11.2). The population-based prevalence of myopia, hyperopia (≥ +2.00 D) and astigmatism was 5.3 per cent, 4.0 per cent and 5.4 per cent, respectively. Combined refractive error and myopia alone were higher in urban areas compared to rural areas (odds ratio [OR]: 2.27 [CI: 2.09-2.45]) and (OR: 2.12 [CI: 1.79-2.50]), respectively. The prevalence of combined refractive errors and myopia alone in schools was higher among girls than boys (OR: 1.2 [CI: 1.1-1.3] and OR: 1.1 [CI: 1.1-1.2]), respectively. However, hyperopia was more prevalent among boys than girls in schools (OR: 2.1 [CI: 1.8-2.4]). Refractive error in children in India is a major public health problem and requires concerted efforts from various stakeholders including the health care workforce, education professionals and parents, to manage this issue.
Topics: Adolescent; Child; Child, Preschool; Female; Humans; India; Infant; Infant, Newborn; Male; Prevalence; Refractive Errors; Risk Factors; Rural Population; Sex Distribution; Urban Population
PubMed: 29682791
DOI: 10.1111/cxo.12689 -
Journal of Current Ophthalmology Mar 2018The aim of the study was a systematic review of refractive errors across the world according to the WHO regions. (Review)
Review
PURPOSE
The aim of the study was a systematic review of refractive errors across the world according to the WHO regions.
METHODS
To extract articles on the prevalence of refractive errors for this meta-analysis, international databases were searched from 1990 to 2016. The results of the retrieved studies were merged using a random effect model and reported as estimated pool prevalence (EPP) with 95% confidence interval (CI).
RESULTS
In children, the EPP of myopia, hyperopia, and astigmatism was 11.7% (95% CI: 10.5-13.0), 4.6% (95% CI: 3.9-5.2), and 14.9% (95% CI: 12.7-17.1), respectively. The EPP of myopia ranged from 4.9% (95% CI: 1.6-8.1) in South-East Asia to 18.2% (95% CI: 10.9-25.5) in the Western Pacific region, the EPP of hyperopia ranged from 2.2% (95% CI: 1.2-3.3) in South-East Asia to 14.3% (95% CI: 13.4-15.2) in the Americas, and the EPP of astigmatism ranged from 9.8% in South-East Asia to 27.2% in the Americas. In adults, the EPP of myopia, hyperopia, and astigmatism was 26.5% (95% CI: 23.4-29.6), 30.9% (95% CI: 26.2-35.6), and 40.4% (95% CI: 34.3-46.6), respectively. The EPP of myopia ranged from 16.2% (95% CI: 15.6-16.8) in the Americas to 32.9% (95% CI: 25.1-40.7) in South-East Asia, the EPP of hyperopia ranged from 23.1% (95% CI: 6.1%-40.2%) in Europe to 38.6% (95% CI: 22.4-54.8) in Africa and 37.2% (95% CI: 25.3-49) in the Americas, and the EPP of astigmatism ranged from 11.4% (95% CI: 2.1-20.7) in Africa to 45.6% (95% CI: 44.1-47.1) in the Americas and 44.8% (95% CI: 36.6-53.1) in South-East Asia. The results of meta-regression showed that the prevalence of myopia increased from 1993 (10.4%) to 2016 (34.2%) ( = 0.097).
CONCLUSION
This report showed that astigmatism was the most common refractive errors in children and adults followed by hyperopia and myopia. The highest prevalence of myopia and astigmatism was seen in South-East Asian adults. The highest prevalence of hyperopia in children and adults was seen in the Americas.
PubMed: 29564404
DOI: 10.1016/j.joco.2017.08.009 -
Clinical Ophthalmology (Auckland, N.Z.) 2018To systematically review the published evidence on the prevalence and economic and humanistic burden of astigmatism in cataract patients. (Review)
Review
PURPOSE
To systematically review the published evidence on the prevalence and economic and humanistic burden of astigmatism in cataract patients.
MATERIALS AND METHODS
For this systematic literature review, the Medline, PubMed, Embase, and Cochrane databases were searched from 1996 to September 2015 for available scientific literature that met the inclusion criteria. Studies published in the English language reporting prevalence and humanistic and economic burden in patients diagnosed with cataract and astigmatism were included.
RESULTS
Of 3,649 papers reviewed, 31 studies from 32 publications met the inclusion criteria of this review. Preexisting astigmatism ≥1 D was present in up to 47% of cataract eyes. The cost burden of residual uncorrected astigmatism after cataract surgery was driven by the cost of spectacles, which was estimated to range from $2,151 to $3,440 in the US and $1,786 to $4,629 in Europe over a lifetime. In cataract patients, both preexisting and postoperative residual astigmatism were associated with poor vision-related patient satisfaction and quality of life, as well as higher spectacle burden. Astigmatism correction during cataract surgery appears to improve visual outcomes and results in overall lifetime cost savings compared to astigmatism correction with postoperative vision correction.
CONCLUSION
There is a high prevalence of preexisting astigmatism in cataract patients. Although published data are limited, both preoperative astigmatism and postoperative residual astigmatism affect visual function and vision-related quality of life, resulting in increased humanistic burden. Suboptimal correction of astigmatism during cataract surgery drives the continuous need for vision correction with spectacles in the postoperative period. Patients must bear the out-of-pocket expenses, since payers often do not reimburse the cost of spectacles. Greater access to astigmatism correction during cataract surgery could improve visual outcomes and quality of life in patients. More research is required to gain a better understanding of the disease burden of astigmatism in cataract patients.
PubMed: 29563768
DOI: 10.2147/OPTH.S146829 -
Eye and Vision (London, England) 2017Postoperative visual acuity can be limited by post-keratoplasty astigmatism, even with a clear corneal graft. Astigmatism management can be performed by selective suture... (Review)
Review
Postoperative visual acuity can be limited by post-keratoplasty astigmatism, even with a clear corneal graft. Astigmatism management can be performed by selective suture removal, adjustment of sutures, optical correction, photorefractive procedures, wedge resection, intra-ocular lens implantation, intracorneal ring segments, relaxing incisions with or without compression sutures and repeated keratoplasty. Relaxing incisions can be made in the graft, graft-host interface or host cornea. Despite the unpredictability of the method because the flat and steep meridians are usually not orthogonal after penetrating keratoplasty, with asymmetric power distribution, all the studies showed an overall reduction of refractive, keratometric or topographic astigmatism, ranging from 30% to 72% with manual or femtosecond-assisted techniques. Most patients with astigmatism higher than 6 diopters had residual cylinder less than or equal to 3 diopters, which can be treated by laser excimer ablation or secondary intraocular lens implantation.
PubMed: 29238735
DOI: 10.1186/s40662-017-0093-7 -
The prevalence of visual disorders in Iranian students: A meta-analysis study and systematic review.Electronic Physician Oct 2017Visual defects have dramatic effects on health, self-esteem, and educational function of students, and delayed diagnosis will cause complications, like academic failure...
BACKGROUND
Visual defects have dramatic effects on health, self-esteem, and educational function of students, and delayed diagnosis will cause complications, like academic failure and psychologic disorders.
OBJECTIVE
The present study aimed to investigate the prevalence of ocular disorders in Iranian students in a systematic review.
METHODS
We searched databases, including PubMed, SID, Magiran, Google Scholar, and Iranmedex using the following keywords in Persian and English: disorders, vision, amblyopia, refractive errors, astigmatism, student, and Iran with all the possible combinations, important, chief, and sensitive words. Search resulted in 28 articles, conducted during a period from 1996 to 2014 in Iran and their data was analyzed using meta-analysis and random effects model. Heterogeneity of studies was assessed using I2 index, and data was finally analyzed with R Software and STATA (Version 11.2).
RESULTS
Total number of subjects in the study was 1,117,274, aged 2 to 18 years. The prevalence of disorders related to amblyopia, refractive error, and strabismus was 8%, 7% and 1%, respectively. The greatest amount of refractive error was related to astigmatism (19%) followed by myopia (17%).
CONCLUSION
According to the study results, the prevalence of visual disorders among Iranian students indicated the critical necessity of screening programs for prevention of visual disorders in this age group.
PubMed: 29238492
DOI: 10.19082/5516 -
Eye and Vision (London, England) 2017The refractive outcomes of glaucoma surgeries, particularly their effect on astigmatism, are incompletely understood. (Review)
Review
BACKGROUND
The refractive outcomes of glaucoma surgeries, particularly their effect on astigmatism, are incompletely understood.
MAIN BODY
Trabeculectomy is associated with a considerable amount of with-the-rule astigmatic change in the immediate postoperative period. This is followed by a gradual against-the-rule shift. These changes are altered with the use of mitomycin C (MMC). Non-penetrating surgery such as deep sclerectomy is also associated with a similar or smaller degree of induced astigmatism. Minimally invasive glaucoma surgery appears to be astigmatically neutral. There is no clear evidence regarding refractive outcomes of glaucoma drainage device surgery.
CONCLUSIONS
Induced astigmatism may account for a reduction in unaided visual acuity in the early postoperative period following a successful trabeculectomy. These changes appear to stabilise at 3 months, and it would be prudent to defer the prescription of new glasses until this time. If sequential cataract surgery is to be performed, toric intraocular lenses can be a useful option for astigmatic correction.
PubMed: 29177182
DOI: 10.1186/s40662-017-0090-x -
The Cochrane Database of Systematic... Sep 2017Age-related cataract is the principal cause of blindness and visual impairment in the world. Phacoemulsification is the main surgical procedure used to treat cataract.... (Review)
Review
BACKGROUND
Age-related cataract is the principal cause of blindness and visual impairment in the world. Phacoemulsification is the main surgical procedure used to treat cataract. The comparative effectiveness and safety of different-sized incisions for phacoemulsification has not been determined.
OBJECTIVES
The aim of this systematic review was to assess the effectiveness and safety of smaller versus larger incisions for phacoemulsification in age-related cataract. The primary outcome of this review was surgically induced astigmatism at three months after surgery.
SEARCH METHODS
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 10), MEDLINE Ovid (1946 to 28 October 2016), Embase Ovid (1947 to 28 October 2016), PubMed (1948 to 28 October 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 28 October 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com; last searched 13 May 2013), ClinicalTrials.gov (www.clinicaltrials.gov; searched 28 October 2016), and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp; searched 28 October 2016). We did not use any date or language restrictions in the electronic searches for trials.
SELECTION CRITERIA
We included randomized controlled trials (RCTs) comparing different-sized incisions in people with age-related cataract undergoing phacoemulsification.
DATA COLLECTION AND ANALYSIS
We used standard methodological procedures expected by Cochrane.
MAIN RESULTS
We included 26 RCTs with a total of 2737 participants (3120 eyes). These trials were conducted in Bosnia and Herzegovina, China, France, India, Italy, Korea, Spain, Switzerland, and Turkey. Half of the 26 trials were conducted in China. We judged all trials as mostly at unclear to low risk of bias. The included RCTs compared four different-sized incisions:<= 1.5 mm, 1.8 mm, 2.2 mm, and approximately 3.0 mm. These incisions were performed using three different techniques: coaxial and biaxial microincision phacoemulsification (C-MICS and B-MICS) and standard phacoemulsification. Not all studies provided data in a form that could be included in this review. Five studies had three arms.Fifteen trials compared C-MICS (2.2 mm) with standard phacoemulsification (about 3.0 mm). Very low-certainty evidence suggested less surgically induced astigmatism in the C-MICS group at three months compared with standard phacoemulsification (mean difference (MD) -0.19 diopters (D), 95% confidence interval (CI) -0.30 to -0.09; 996 eyes; 8 RCTs). There was low-certainty evidence that both groups achieved similar best-corrected visual acuity (MD 0.00 logMAR, 95% CI -0.02 to 0.02; 242 eyes; 3 RCTs). There was low-certainty evidence of little or no difference in endothelial cell loss and central corneal thickness comparing C-MICS with standard phacoemulsification (MD -7.23 cells/mm, 95% CI -78.66 to 64.20; 596 eyes; 4 RCTs) and (MD -0.68 μm, 95% CI -3.26 to 1.90; 487 eyes; 5 RCTs).Nine trials compared C-MICS (1.8 mm) with standard phacoemulsification (about 3.0 mm). Very low-certainty evidence suggested less astigmatism at three months in the C-MICS group compared with standard phacoemulsification group (MD -0.23 D, 95% CI -0.34 to -0.13; 561 eyes; 5 RCTs). Low-certainty evidence suggested little or no difference in best-corrected visual acuity, endothelial cell loss, and central corneal thickness in the two groups at three months (MD -0.02 logMAR, 95% CI -0.03 to -0.00; 192 eyes; 3 RCTs), (MD 7.56 cells/mm, 95% CI -67.65 to 82.77; 380 eyes; 5 RCTs), and (MD -1.52 μm, 95% CI -6.29 to 3.25; 245 eyes; 3 RCTs).Six studies compared C-MICS (1.8 mm) with C-MICS (2.2 mm). There was low-certainty evidence that astigmatism, visual acuity, and central corneal thickness were similar in the two groups at three months (MD 0.04 D, 95% CI -0.09 to 0.16; 259 eyes; 3 RCTs), (MD 0.01 logMAR, 95% CI -0.01 to 0.04; 200 eyes; 3 RCTs), and (MD 0.45 μm, 95% CI -2.70 to 3.60; 100 eyes; 1 RCT). Very low-certainty evidence suggested higher endothelial cell loss in the 1.8 mm group (MD 213.00 cells/mm, 95% CI 11.15 to 414.85; 70 eyes; 1 RCT).Four studies compared B-MICS (<= 1.5 mm) with standard phacoemulsification (about 3.0 mm). Astigmatism was similar in the two groups at three months (MD -0.01 D, 95% CI -0.03 to 0.01; 368 eyes; 2 RCTs; moderate-certainty evidence). There was low-certainty evidence on visual acuity, suggesting little or no difference between the two groups (MD -0.02 logMAR, 95% CI -0.04 to -0.00; 464 eyes; 3 RCTs). Low-certainty evidence on endothelial cell loss and central corneal thickness also suggested little or no difference between the two groups (MD 55.83 cells/mm, 95% CI -34.93 to 146.59; 280 eyes; 1 RCT) and (MD 0.10 μm, 95% CI -14.04 to 14.24; 90 eyes; 1 RCT).None of the trials reported on quality of life. One trial reported that no participants experienced endophthalmitis or posterior capsule rupture; they also reported little or no difference between incision groups regarding corneal edema (risk ratio 1.02, 95% CI 0.40 to 2.63; 362 eyes).
AUTHORS' CONCLUSIONS
Phacoemulsification with smaller incisions was not consistently associated with less surgically induced astigmatism compared with phacoemulsification with larger incisions. Coaxial microincision phacoemulsification may be associated with less astigmatism than standard phacoemulsification, but the difference was small, in the order of 0.2 D, and the evidence was uncertain. Safety outcomes and quality of life were not adequately reported; these should be addressed in future studies.
Topics: Astigmatism; Cataract; Corneal Edema; Corneal Pachymetry; Humans; Phacoemulsification; Postoperative Complications; Randomized Controlled Trials as Topic; Surgical Wound; Visual Acuity
PubMed: 28931202
DOI: 10.1002/14651858.CD010510.pub2 -
The Cochrane Database of Systematic... Feb 2017Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Near-sightedness, or myopia, is a condition in which light rays entering the eye along the visual axis focus in front of the retina, resulting in blurred vision. Myopia can be treated with spectacles, contact lenses, or refractive surgery. Options for refractive surgery include laser-assisted subepithelial keratectomy (LASEK) and laser-assisted in-situ keratomileusis (LASIK). Both procedures utilize a laser to shape the corneal tissue (front of the eye) to correct refractive error, and both create flaps before laser treatment of corneal stromal tissue. Whereas the flap in LASEK is more superficial and epithelial, in LASIK it is thicker and also includes some anterior stromal tissue. LASEK is considered a surface ablation procedure, much like its predecessor, photorefractive keratectomy (PRK). LASEK was developed as an alternative to PRK to address the issue of pain associated with epithelial debridement used for PRK. Assessing the relative benefits and risks/side effects of LASEK and LASIK warrants a systematic review.
OBJECTIVES
To assess the effects of LASEK versus LASIK for correcting myopia.
SEARCH METHODS
We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Eyes and Vision Trials Register (2016, Issue 10); MEDLINE Ovid (1946 to 24 October 2016); Embase.com (1947 to 24 October 2016); PubMed (1948 to 24 October 2016); LILACS (Latin American and Caribbean Health Sciences Literature Database; 1982 to 24 October 2016); the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), last searched 20 June 2014; ClinicalTrials.gov (www.clinicaltrials.gov); searched 24 October 2016; and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 24 October 2016. We did not use any date or language restrictions in the electronic searches for trials.
SELECTION CRITERIA
We considered only randomized controlled trials (RCTs) for the purposes of this review. Eligible RCTs were those in which myopic participants were assigned randomly to receive either LASEK or LASIK in one or both eyes. We also included paired-eye studies in which investigators randomly selected which of the participant's eyes would receive LASEK or LASIK and assigned the other eye to the other procedure. Participants were men or women between the ages of 18 and 60 years with myopia up to 12 diopters (D) and/or myopic astigmatism of severity up to 3 D, who did not have a history of prior refractive surgery.
DATA COLLECTION AND ANALYSIS
Two review authors independently screened all reports and assessed the risk of bias in trials included in this review. We extracted data and summarized findings using risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes. In the absence of clinical and methodological heterogeneity across trials, we used a random-effects model to calculate summary effect estimates. We used a fixed-effect model when including fewer than three trials in a meta-analysis. When clinical, methodological, or statistical heterogeneity was observed across trials, we reported our findings in a narrative synthesis.
MAIN RESULTS
We identified four eligible trials with 538 eyes of 392 participants for the review, but only three trials (154 participants) provided outcome data for analysis. We found no ongoing trials. Two of four trials were from China, one trial was from Turkey, and the location of one trial was not reported. The risk of bias for most domains was unclear due to poor reporting of trial methods; no trial had a protocol or trial registry record. Three trials enrolled participants with mild to moderate myopia (less than -6.50 D); one trial included only participants with severe myopia (more than -6.00 D).The evidence showed uncertainty in whether there is a difference between LASEK and LASIK in uncorrected visual acuity (UCVA) at 12 months, the primary outcome in our review. The RR and 95% confidence interval (CI) at 12 months after surgery was 0.96 (95% CI 0.82 to 1.13) for UCVA of 20/20 or better and 0.90 (95% CI 0.67 to 1.21) for UCVA of 20/40 or better based on data from one trial with 57 eyes (very low-certainty evidence). People receiving LASEK were less likely to achieve a refractive error within 0.5 diopters of the target at 12 months follow-up (RR 0.69, 95% CI 0.48 to 0.99; 57 eyes; very low-certainty evidence). One trial reported mild corneal haze at six months in one eye in the LASEK group and none in the LASIK group (RR 2.11, 95% CI 0.57 to 7.82; 76 eyes; very low-certainty evidence). None of the included trials reported postoperative pain score or loss of visual acuity, spherical equivalent of the refractive error, or quality of life at 12 months.Refractive regression, an adverse event, was reported only in the LASEK group (8 of 37 eyes) compared with none of 39 eyes in the LASIK group in one trial (low-certainty evidence). Other adverse events, such as corneal flap striae and refractive over-correction, were reported only in the LASIK group (5 of 39 eyes) compared with none of 37 eyes in the LASEK group in one trial (low-certainty evidence).
AUTHORS' CONCLUSIONS
Overall, from the available RCTs, there is uncertainty in how LASEK compares with LASIK in achieving better refractive and visual results in mildly to moderately myopic participants. Large, well-designed RCTs would be required to estimate the magnitude of any difference in efficacy or adverse effects between LASEK and LASIK for treating myopia or myopic astigmatism.
Topics: Adult; Female; Humans; Keratectomy, Subepithelial, Laser-Assisted; Keratomileusis, Laser In Situ; Male; Middle Aged; Myopia; Quality of Life; Randomized Controlled Trials as Topic; Visual Acuity
PubMed: 28197998
DOI: 10.1002/14651858.CD011080.pub2