Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

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Photorefractive keratectomy (PRK) versus laser assisted in

situ keratomileusis (LASIK) for hyperopia correction (Review)

Settas G, Settas C, Minos E, Yeung IYL

This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published inThe Cochrane Library

2012, Issue 6

http://www.thecochranelibrary.com

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T A B L E O F C O N T E N T S 1 HEADER . . . . 1 ABSTRACT . . . . 2

PLAIN LANGUAGE SUMMARY . . . .

2 BACKGROUND . . . . 3 OBJECTIVES . . . . 3 METHODS . . . . 5 RESULTS . . . . 5 DISCUSSION . . . . 6 AUTHORS’ CONCLUSIONS . . . . 6 ACKNOWLEDGEMENTS . . . . 6 REFERENCES . . . . 7 CHARACTERISTICS OF STUDIES . . . . 9 DATA AND ANALYSES . . . .

9 APPENDICES . . . . 11 WHAT’S NEW . . . . 11 HISTORY . . . . 12 CONTRIBUTIONS OF AUTHORS . . . . 13 DECLARATIONS OF INTEREST . . . . 13

DIFFERENCES BETWEEN PROTOCOL AND REVIEW . . . .

13

INDEX TERMS . . . .

i Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

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[Intervention Review]

Photorefractive keratectomy (PRK) versus laser assisted in

situ keratomileusis (LASIK) for hyperopia correction

George Settas1_{, Clare Settas}2_{, Evangelos Minos}3_{, Ian YL Yeung}4

1_{Optimax plc, London, UK.}2_{Fitzwilliam Hospital, Peterborough, UK.}3_{Ophthalmology Department, University Hospital of} Herak-lion, Crete, Greece.4_{Ophthalmology Department, Level S8, Queen Mary Hospital, Hong Kong SAR, China}

Contact address: George Settas, Optimax plc, 128 Finchley Road, London, NW3 5HT, UK.settasg@doctors.org.uk. Editorial group:Cochrane Eyes and Vision Group.

Publication status and date:New search for studies and content updated (no change to conclusions), published in Issue 6, 2012. Review content assessed as up-to-date: 17 February 2012.

Citation: Settas G, Settas C, Minos E, Yeung IYL. Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileu-sis (LASIK) for hyperopia correction. Cochrane Database of Systematic Reviews 2012, Issue 6. Art. No.: CD007112. DOI: 10.1002/14651858.CD007112.pub3.

A B S T R A C T Background

Hyperopia, or hypermetropia (also known as long-sightedness or far-sightedness), is the condition where the unaccommodating eye brings parallel light to a focus behind the retina instead of on it. Hyperopia can be corrected with both non-surgical and surgical methods, among them photorefractive keratectomy (PRK) and laser assisted In situ keratomileusis (LASIK). There is uncertainty as to whether hyperopic-PRK or hyperopic-LASIK is the better method.

Objectives

The objectives of this review were to determine whether PRK or LASIK leads to more reliable, stable and safe results when correcting a hyperopic refractive error.

Search methods

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library2012, Issue 2), MEDLINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), themetaRegister of Controlled Trials (mRCT) ( www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) ( www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 17 February 2012. When trials are included in the review we will search the reference lists of the studies included in the review for information about further trials. We will use the Science Citation Index to search for papers that cite any studies included in this review. We did not handsearch journals or conference proceedings specifically for this review.

Selection criteria

We planned to include only randomised controlled trials (RCTs) comparing PRK against LASIK for correction of hyperopia and then perform a sensitivity analysis of pre- and post-millennial trials since this is the mid-point in the history of both PRK and LASIK. Data collection and analysis

We did not identify any studies that met the inclusion criteria for this review.

1 Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

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Main results

As no studies met the inclusion criteria for this review, we discussed the results of non-randomised trials comparing hyperopic-PRK with hyperopic-LASIK.

Authors’ conclusions

No robust, reliable conclusions could be reached, but the non-randomised trials reviewed appear to be in agreement that hyperopic-PRK and hyperopic-LASIK are of comparable efficacy. High quality, well-planned open RCTs are needed in order to obtain a robust clinical evidence base.

P L A I N L A N G U A G E S U M M A R Y

Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for correction of long-sightedness Hyperopia (long-sightedness or far-sightedness) is the condition where the relaxed eye brings parallel light to a focus behind the retina instead of on it. In order to correct hyperopia a variety of surgical techniques can be applied including PRK and LASIK. There exists an uncertainty as to which technique provides more accurate, stable and safe results. As no randomised controlled trials were found that met the inclusion criteria, we could not find definite answers to these questions and therefore concluded that more research is required.

B A C K G R O U N D

Description of the condition

Hyperopia, or hypermetropia (also known as long-sightedness or far-sightedness), is the condition where the unaccommodating (i.e. relaxed) eye brings parallel light to a focus behind the retina instead of on it. The overall refractive power of the eye (i.e. the ability to converge parallel light to a focus) is a function of: a) its axial length and b) the refractive power of the cornea and the crystalline lens. In hyperopia, either because the axial length is too short (axial hyperopia) or the overall refractive power of the eye is too low (refractive hyperopia), parallel light comes to a focus behind the retina.

The prevalence of hypermetropia appears to vary with age, country and ethnic group. It has been postulated that from the age of six to 18 years the prevalence of hyperopia decreases with increasing age (Czepita 2005) and that there are significant differences in the prevalence of refractive errors among ethnic groups, even after controlling for age and sex (Kleinstein 2003). In a study of the US, Western European, and Australian year 2000 populations, the estimated crude prevalence for hyperopia of +3 dioptres (D) or greater in people aged 40 years or older was 9.9%, 11.6%, and 5.8%, respectively (Kempen 2004).

Hyperopic patients may be able to see well in the distance, pro-vided they are young and the refractive error is not too high. Chil-dren with significant hypermetropia may complain of frequent

headaches, rub their eyes often, have a lack of interest in or have difficulty reading. Young children with significant hypermetropia can also develop a convergent squint. Hypermetropia accompa-nied by significant anisometropia (where the two eyes have un-equal refractive power) in children may lead to amblyopia if left untreated.

Uncorrected or undercorrected hyperopic adults may experience blurred vision - especially when viewing near objects - and as-thenopia (visual discomfort, including burning eye sensation and tearing, fatigue after reading even for short periods and even bifrontal headaches exacerbated by near work) (Wilson II 1996).

Description of the intervention

Spectacles and contact lenses are the most commonly used meth-ods to correct a refractive error. Both these methmeth-ods are relatively safe, non-invasive and reversible. There is a variety of surgical techniques available, aiming at modifying the lenticular refractive power, the corneal refractive power, or both.

The lenticular refractive power can be modified by phakic intraoc-ular lens insertion; where the crystalline lens is maintained or by refractive lens exchange; where the crystalline lens is removed and replaced by an intraocular lens implant.

Several laser and non-laser refractive surgical procedures have been used to modify the shape of the cornea and correct a refractive er-ror (be it myopia, hyperopia and/or astigmatism), thereby restor-2 Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

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ing the focus plane of parallel light on the retina. The safety, effi-cacy, and predictability of the surgical outcomes have greatly im-proved since the introduction of the excimer laser and continue to improve as more advanced ophthalmological instruments become available. Despite these advances however, certain limitations and complications (infection, ectasia, diffuse lamellar keratitis, subep-ithelial haze, dry eye, epsubep-ithelial ingrowth, buttonholed flap, free-cap etc.) still exist (Sakimoto 2006).

How the intervention might work

In hyperopia, both photorefractive keratectomy (PRK) and laser assisted In situ keratomileusis (LASIK) employ the ophthalmic excimer laser in order to steepen the cornea and thus increase its refractive power. In the case of PRK the excimer laser is applied on the surface of the cornea after the corneal epithelium has been removed. In LASIK the creation of a thin corneal flap (with the aid of a blade or a laser beam) is followed by the excimer laser application on the underlying corneal tissue.

Why it is important to do this review

It is accepted that PRK is associated with more postoperative pain than LASIK, a slower visual recovery and a higher incidence of corneal haze (El-Agha 2000;El-Agha 2003a;El-Agha 2003b). To our knowledge the question of which of these two methods for correction of hyperopia is more accurate, more stable and more safe than the other has not been addressed to date by a systematic review. The purpose of this review was to evaluate data from ran-domised controlled trials (RCTs) in order to address this question.

O B J E C T I V E S

The objective of this review was to compare PRK to LASIK for the correction of hyperopia by evaluating the postoperative uncor-rected visual acuity, the refractive outcome, the potential loss of best spectacle corrected visual acuity, the postoperative pain and the incidence of adverse outcomes such as subepithelial haze, flap-related complications and corneal ectasia.

M E T H O D S

Criteria for considering studies for this review

Types of studies

As both procedures have evolved and their outcomes improved in the last few years due to the advent of wavefront and corneal topographic analysis software, as well as faster and more efficient excimer laser delivery systems with iris registration and tracking technologies, it is important to compare the latest techniques for PRK with the latest techniques for LASIK. We therefore aimed to include all RCTs in this review but would then perform a sensitivity analysis of pre- and post-millennial trials since this is the midpoint in the history of PRK and LASIK.

Types of participants

We only considered trials in which the participants were males or females over 18 years of age and underwent PRK or LASIK for correction of any degree of primary hyperopia, including hyper-opic astigmatism. It has been postulated that excimer laser cor-rection of hyperopia and hyperopic astigmatism in children and adolescents has the potential to correct refractive errors, improve visual function in amblyopic eyes, correct accommodative strabis-mus, and improve binocular vision (Dvali 2005). However, as the refractive error of patients under the age of 18 tends to change as part of their somatic development, we decided to exclude studies with such participants from our review.

Patients with a history of previous refractive or other eye surgery, co-existing ocular pathology or systemic disease that affects wound healing were also excluded.

Types of interventions

We included studies in which PRK was compared to LASIK for correction of any degree of hyperopia, including hyperopic astig-matism.

Types of outcome measures

Primary outcomes

Our primary outcome was the percentage of eyes within ±0.50 D of target refraction at 12 months post-treatment.

Secondary outcomes

Our secondary outcomes were as follows.

i. Percentage of eyes within ±0.50 D of target refraction at six months or less post-treatment.

ii. Percentage of eyes that lost 2 or more lines of best spectacle corrected visual acuity (BSCVA) at 12 months post-treatment. iii. Percentage of eyes that lost 2 or more lines of best spectacle corrected visual acuity (BSCVA) at six months or less post-treat-ment.

iv. Percentage of eyes with uncorrected visual acuity (UCVA) of 20/20 or better at less than six months or less post-treatment.

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v. Percentage of eyes with uncorrected visual acuity (UCVA) of 20/20 or better at 12 months post-treatment.

vi. Percentage of eyes with uncorrected visual acuity (UCVA) of 20/40 or better at six months or less post-treatment.

vii. Percentage of eyes with uncorrected visual acuity (UCVA) of 20/40 or better at 12 months post-treatment.

Adverse outcomes

i. Incidence of corneal ectasia.

ii. Incidence of flap-associated complications in eyes that under-went LASIK.

iii. Incidence of sub-epithelial haze in eyes that underwent PRK. iv. Postoperative pain scores.

v. Incidence of symptoms attributed to dry eyes post-treatment.

Search methods for identification of studies

Electronic searches

We searched the Cochrane Central Register of Controlled Tri-als (CENTRAL) 2012, Issue 2, part of The Cochrane Library. www.thecochranelibrary.com(accessed 17 February 2012), MED-LINE (January 1950 to February 2012), EMBASE (January 1980 to February 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to February 2012), themetaRegister of Controlled Trials (mRCT) ( www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no language or date restrictions in the search for trials. The electronic databases were last searched on 17 February 2012.

See: Appendices for details of search strategies for CENTRAL (Appendix 1), MEDLINE (Appendix 2), EMBASE (Appendix 3), LILACS (Appendix 4),mRCT (Appendix 5), ClinicalTrials.gov (Appendix 6) and the ICTRP (Appendix 7).

Searching other resources

When trials are included in the review, we will search the reference lists of the studies included in the review for information about further trials. We will use the Science Citation Index to search for papers that cite any studies included in this review. We did not handsearch journals or conference proceedings specifically for this review.

Data collection and analysis

Selection of studies

All three review authors working independently assessed the ti-tles and abstracts resulting from the searches. The full copies of all relevant studies were screened by all three authors against the inclusion criteria.

No relevant RCTs were identified from our search, but if we do find any RCTs in the future, we will follow the methodological process below.

Data extraction and management

Two review authors (SG and SC) will extract data independently using a standard data collection form and will enter data inde-pendently into Review Manager 5 (Review Manager 2011). The results will be compared and any disagreements will be resolved by discussion. Details will be extracted from the studies on the fol-lowing: methods, participants, interventions, outcomes and notes.

Assessment of risk of bias in included studies

All three review authors will assess studies that meet the inclusion criteria for methodological quality, as described in Chapter 8 of the

Cochrane Handbook for Systematic Reviews of Interventions(Higgins 2011). We will consider the following parameters:

i. random sequence generation; ii. allocation concealment;

iii. masking (blinding) of participants, personnel and outcome assessors;

iv. incomplete outcome data; v. selective outcome reporting; vi. other sources of bias.

Each review author will grade each parameter independently as low risk of bias, high risk of bias or unclear (uncertain risk of bias). Studies that score unclear in any of the parameters will be dealt with by contacting the authors for clarification and additional in-formation. Potential disagreements between the three review au-thors will be resolved by discussion. We will include all trials in our analysis initially, except those graded as high risk of bias on random sequence generation.

Measures of treatment effect

All outcome measures stated are dichotomous, with the exception of ’postoperative pain scores’ which is ordinal. For dichotomous outcomes an odds ratio will be calculated. For continuous out-comes, the mean difference will be calculated.

Unit of analysis issues

The preferred unit of analysis will be outcomes for eyes rather than individuals, since some individuals might have had unilateral treatment or different treatment in each eye.

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Dealing with missing data

In case we are unable to extract all the information we are interested in from published reports, both with regard to the details of the study and its numerical results, we will request the missing data from the original investigators.

Assessment of heterogeneity

When we review the studies, we will endeavour to identify differ-ences between them which are likely to introduce heterogeneity. As some degree of heterogeneity will always exist due to the clinical and methodological diversity of the studies, we will employ the results of the I2_{measure to quantify inconsistencies across studies.}

Assessment of reporting biases

In order to investigate whether our review is subject to reporting bi-ases, we will use RevMan to prepare the relevant funnel plot which will be examined for signs of asymmetry as detailed in Chapter 10 of theCochrane Handbook for Systematic Reviews of Interventions

(Sterne 2011).

Data synthesis

If there is no substantial statistical heterogeneity, and if there is no clinical heterogeneity between the trials, we will combine the results in a meta-analysis using a random-effects model. A fixed-effect model will be used if the number of trials is three or less. If heterogeneity is present, we will not combine the studies in a meta-analysis but will present the details in a tabulated summary.

Subgroup analysis and investigation of heterogeneity We will initially analyze data from all eligible studies. We will then perform subgroup analyses to investigate for heterogeneity for the following subgroups of hyperopia: low to moderate hyperopia (≤

+4.0 D) and moderate to high hyperopia (> +4.0 D).

Sensitivity analysis

Sensitivity analyses will be performed, in order to evaluate how robust the results of the review are relative to decisions and as-sumptions made in the process of conducting the review. We will include all trials in our analysis initially, except those graded as ’high risk of bias’ on ’sequence generation’. We will then examine the effect of excluding trials graded as ’high risk of bias’ on any of the parameters by repeating the analysis without these.

R E S U L T S

Description of studies

See:Characteristics of excluded studies;Characteristics of ongoing studies.

Results of the search

The electronic searches yielded 339 titles and abstracts. The Tri-als Search Co-ordinator (TSC) scanned the search results and re-moved any references which were not relevant to the scope of the review. We obtained the full text copies of five studies, which after further assessment were all excluded as none were RCTs. An update search was done in February 2012 which yielded a fur-ther 12 references. The TSC scanned the search results and re-moved 11 references which were not relevant to the scope of the review. We screened the remaining reference which is an ongoing study from ClinicalTrials.gov. Currently there is not enough in-formation to adequately assess this study for potential inclusion in the review therefore we will assess this study when further in-formation becomes available.

Included studies

No studies met the inclusion criteria.

Excluded studies

We excluded five studies (El-Agha 2000;El-Agha 2003a;El-Agha 2003b; Sciscio 2003;Stein 1999). For further details see the ’ Characteristics of excluded studies’ table.

Risk of bias in included studies

As no studies met the inclusion criteria, risk of bias was not as-sessed.

Effects of interventions

As no studies met the inclusion criteria, no meta-analysis was per-formed.

D I S C U S S I O N

Our search identified no RCTs. We therefore discuss the data available from the five excluded studies comparing PRK against LASIK for correction of hyperopia and hyperopic astigmatism. These studies were non-randomised and both ’sequence genera-tion’ and ’allocation concealment’ were open to bias.

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In a large, prospective, non-randomised study by Stein et al. 200 eyes underwent PRK and 186 LASIK with the VISX STAR Ex-cimer Laser System for hyperopia up to +8.00 D and followed up to 24 months (Stein 1999). This study examined the postoperative spherical equivalent (SE), uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), epithelial healing time and complication rate. It was demonstrated that although similar SE was achieved in the long term, eyes that underwent LASIK ex-perienced less discomfort, faster visual recovery and less hyperopic regression. The incidence of significant loss of BSCVA (2 lines) was 1% in both groups, while the complication rate was 4.5% in the PRK group and 1.6% in the LASIK group. The epithelial healing time was predictably longer for the PRK group. These results are in keeping with the findings of later studies which compared PRK against LASIK for the correction of spherical hy-peropia (El-Agha 2000;El-Agha 2003a) and compound hyper-opic astigmatism (El-Agha 2003b). In all three studies PRK and LASIK were deemed of comparable efficacy and safety. PRK was associated with significant postoperative pain, initial and tempo-rary myopic overcorrection which self-corrected within three to six months and an incidence of mild peripheral haze up to 19.5%. LASIK was less painful and was associated with more rapid refrac-tion stability (at one month) and less initial myopic overcorrec-tion. The long term efficacy and stability of astigmatic correction were similar in both groups.

A separate study utilised Fourier analysis of corneal topographic data to determine differences in induced irregular corneal astig-matism following spherical hyperopic correction by PRK versus LASIK (Sciscio 2003). It concluded that both procedures induced an equal amount of irregular corneal astigmatism which peaked at three months post-op and then decreased over the next nine months, with no statistically significant difference between the PRK and LASIK group at any time point.

A U T H O R S ’ C O N C L U S I O N S

Implications for practice

To date there are only a few studies comparing PRK with LASIK di-rectly for hyperopia correction. These studies are non-randomised and as a rule include a small number of patients. Despite general agreement regarding the efficacy, safety and stability of postop-erative refraction of hyperopic PRK or LASIK, firm and robust conclusions cannot be deduced from the available data.

Implications for research

Well-planned, large, high quality RCTs comparing hyperopic-PRK with hyperopic-LASIK are required, in order to provide a robust and reliable clinical evidence base. These studies must have a random sequence generation for the participants and the allo-cation sequence must be adequately concealed. As masking of the surgeon or the patient to the administered surgical intervention is nigh impossible, it is unavoidable that the trials will be open. The assessor of the primary and secondary outcomes however could and should be masked to the surgical intervention.

A C K N O W L E D G E M E N T S

We would like to thank Anupa Shah, Richard Wormald, Catey Bunce, Roberta Scherer and Dr Neal Sher for peer-reviewing this review and for all their helpful comments. We are grateful to Iris Gordon for carrying out the electronic searches for this review. Richard Wormald (Co-ordinating Editor for CEVG) acknowl-edges financial support for his CEVG research sessions from the Department of Health through the award made by the National Institute for Health Research to Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology for a Spe-cialist Biomedical Research Centre for Ophthalmology. The views expressed in this publication are those of the authors and not nec-essarily those of the Department of Health.

R E F E R E N C E S References to studies excluded from this review

El-Agha 2000 {published data only}

El-Agha MS, Johnston EW, Bowman RW, Cavanagh HD, McCulley JP. Excimer laser treatment of spherical hyperopia: PRK or LASIK?.Transactions of the American Ophthalmological Society2000;98:59–66.

El-Agha 2003a {published data only}

El-Agha MS, Johnston EW, Bowman RW, Cavanagh HD, McCulley JP. Photorefractive keratectomy versus laser in situ keratomileusis for the treatment of spherical hyperopia. Eye Contact Lens2003;29(1):31–7.

El-Agha 2003b {published data only}

El-Agha MS, Bowman RW, Cavanagh HD, McCulley JP. Comparison of photorefractive keratectomy and laser in situ keratomileusis for the treatment of compound hyperopic astigmatism. Journal of Cataract and Refractive Surgery 2003;29(5):900–7.

Sciscio 2003{published data only}

Sciscio A, Hull CC, Stephenson CG, Baldwin H, O’Brart D, Marshall J. Fourier analysis of induced irregular astigmatism. Photorefractive keratectomy versus laser in situ keratomileusis in a bilateral cohort of hyperopic patients.Journal of Cataract and Refractive Surgery2003;29

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(9):1709–17.

Stein 1999 {published data only}

Stein RM. Comparison between hyperopic PRK and hyperopic LASIK with the VISX STAR excimer laser system.American Academy of Ophthalmology1999:246. References to ongoing studies

NCT01135719 {published data only}

NCT01135719. A comparison of fellow eyes undergoing LASIK or PRK with a wavefront-guided excimer laser versus a wavefront-optimized excimer laser. clinicaltrials.gov/ct2/ show/NCT01135719 (accessed 20 February 2012). Additional references

Czepita 2005

Czepita D, Goslawski W, Mojsa A. Occurrence of hyperopia among students ranging from 6 to 18 years of age.Klinika Oczna2005;107(1-3):96–9.

Dvali 2005

Dvali ML, Tsintsadze NA, Mirtskhulava SI. Features of hyperopic LASIK in children.Journal of Refractive Surgery 2005;21(5 Suppl):S614–6.

Glanville 2006

Glanville JM, Lefebvre C, Miles JN, Camosso-Stefinovic J. How to identify randomized controlled trials in MEDLINE: ten years on.Journal of the Medical Library Association2006; 94(2):130–6.

Higgins 2011

Higgins JPT, Altman DG, Sterne JAC (editors). Chapter 8: Assessing risk of bias in included studies. In: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 (updated March 2011). The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.

Kempen 2004

Kempen JH, Mitchell P, Lee KE, Tielsch JM, Broman AT, Taylor HR, et al.The prevalence of refractive errors among adults in the United States, Western Europe, and Australia. Archives of Ophthalmology2004;122(4):495–505. Kleinstein 2003

Kleinstein RN, Jones LA, Hullett S, Kwon S, Lee RJ, Friedman NE, et al.Refractive error and ethnicity in children.Archives of Ophthalmology2003;121(8):1141–7. Review Manager 2011

The Nordic Cochrane Centre, The Cochrane Collaboration. Review Manager (RevMan). 5.1. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2011. Sakimoto 2006

Sakimoto T, Rosenblatt MI, Azar DT. Laser eye surgery for refractive errors.Lancet2006;367(9520):1432–47. Sterne 2011

Sterne JAC, Egger M, Moher D (editors). Chapter 10: Addressing reporting biases. In: Higgins JPT, Green S (editors). Cochrane Handbook for Systematic Reviews of Intervention. Version 5.1.0 (updated March 2011). The Cochrane Collaboration, 2011. Available from www.cochrane-handbook.org.

Wilson II 1996

Wilson II FM.Practical Ophthalmology: a Manual for Beginning Residents. 4th Edition. San Francisco: American Academy of Ophthalmology, 1996.

References to other published versions of this review Settas 2009

Settas G, Settas C, Minos E, Yeung IYL. Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction. Cochrane Database of Systematic Reviews2009, Issue 2. [DOI: 10.1002/ 14651858.CD007112.pub2]

∗

Indicates the major publication for the study

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C H A R A C T E R I S T I C S O F S T U D I E S

Characteristics of excluded studies [ordered by study ID]

Study Reason for exclusion El-Agha 2000 Non-randomised study El-Agha 2003a Non-randomised study El-Agha 2003b Non-randomised study Sciscio 2003 Non-randomised study Stein 1999 Non-randomised study

Characteristics of ongoing studies [ordered by study ID]

NCT01135719

Trial name or title A comparison of fellow eyes undergoing LASIK or PRK with a wavefront-guided excimer laser versus a wavefront-optimised excimer laser

Methods Subjects with myopia, hyperopia and astigmatism are being randomised by ocular dominance to be treated with either PRK or LASIK. One eye will be treated with a wavefront-guided excimer laser and the fellow eye will be treated with a wavefront optimised excimer laser

Participants Participants 21 years and older

Interventions Wavefront-guided excimer laser versus wavefront-optimised excimer laser Outcomes Changes in best spectacle corrected visual acuity

Changes in 25 and 5% low contrast visual acuity Improvement in uncorrected visual acuity Changes in higher order aberrations Starting date April 2009

Contact information Edward E. Manche, Stanford University School of Medicine, Stanford University Notes

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D A T A A N D A N A L Y S E S

This review has no analyses.

A P P E N D I C E S

Appendix 1. CENTRAL search strategy

#1 MeSH descriptor Hyperopia #2 hyperop* or hypermetrop* #3 far next sight*

#4 long next sight* #5 farsight* #6 longsight*

#7 (#1 OR #2 OR #3 OR #4 OR #5 OR #6) #8 MeSH descriptor Photorefractive Keratectomy #9 keratectom*

#10 PRK

#11 (#8 OR #9 OR #10)

#12 MeSH descriptor Keratomileusis, Laser In Situ #13 keratomileusis

#14 LASIK

#15 (#12 OR #13 OR #14) #16 (#7 AND #11 AND #13)

Appendix 2. MEDLINE (OvidSP) search strategy

1. randomized controlled trial.pt. 2. (randomized or randomised).ab,ti. 3. placebo.ab,ti. 4. dt.fs. 5. randomly.ab,ti. 6. trial.ab,ti. 7. groups.ab,ti. 8. or/1-7 9. exp animals/ 10. exp humans/ 11. 9 not (9 and 10) 12. 8 not 11 13. hyperopia/ 14. (hyperop$ or hypermetrop$).tw. 15. (far adj1 sight$).tw.

16. (long adj1 sight$).tw. 17. farsight$.tw. 18. longsight$.tw. 19. or/13-18 20. photorefractive keratectomy/ 21. keratectom$.tw. 22. PRK.tw. 9 Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

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23. or/20-22

24. keratomileusis, laser in situ/ 25. keratomileusis.tw.

26. LASIK.tw. 27. or/24-26 28. 19 and 23 and 27 29. 12 and 28

The search filter for trials at the beginning of the MEDLINE strategy is from the published paper by Glanville et al (Glanville 2006).

Appendix 3. EMBASE (OvidSP) search strategy

1. exp randomized controlled trial/ 2. exp randomization/

3. exp double blind procedure/ 4. exp single blind procedure/ 5. random$.tw.

6. or/1-5

7. (animal or animal experiment).sh. 8. human.sh.

9. 7 and 8 10. 7 not 9 11. 6 not 10 12. exp clinical trial/ 13. (clin$ adj3 trial$).tw.

14. ((singl$ or doubl$ or trebl$ or tripl$) adj3 (blind$ or mask$)).tw. 15. exp placebo/

16. placebo$.tw. 17. random$.tw.

18. exp experimental design/ 19. exp crossover procedure/ 20. exp control group/ 21. exp latin square design/ 22. or/12-21

23. 22 not 10 24. 23 not 11

25. exp comparative study/ 26. exp evaluation/ 27. exp prospective study/

28. (control$ or prospectiv$ or volunteer$).tw. 29. or/25-28 30. 29 not 10 31. 30 not (11 or 23) 32. 11 or 24 or 31 33. hypermetropia/ 34. (hyperop$ or hypermetrop$).tw. 35. (far adj1 sight$).tw.

36. (long adj1 sight$).tw. 37. farsight$.tw. 38. longsight$.tw. 39. or/33-38 40. photorefractive keratectomy/ 41. keratectom$.tw. 10 Photorefractive keratectomy (PRK) versus laser assisted in situ keratomileusis (LASIK) for hyperopia correction (Review)

(13)

42. PRK.tw. 43. or/40-42 44. keratomileusis/ 45. keratomileusis.tw. 46. LASIK.tw. 47. or/44-46 48. 39 and 43 and 47 49. 32 and 48

Appendix 4. LILACS search strategy

hyperopia or hypermetropia and keratectom$ or PRK and keratomileusis or LASIK

Appendix 5.