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Laser-assisted subepithelial keratectomy (LASEK) versus photorefractive keratectomy (PRK) for correction of myopia

  • Review
  • Intervention


  • Shi-Ming Li,

    1. Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing, China
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  • Siyan Zhan,

    1. School of Public Health, Peking University, Centre for Evidence Based Medicine and Clinical Research, Department of Epidemiology and Biostatistics, Beijing, China
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  • Si-Yuan Li,

    1. Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing, China
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  • Xiao-Xia Peng,

    1. Capital Medical University, School of Public Health, Beijing, China
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  • Jing Hu,

    1. School of Public Health, Peking University, Centre for Evidence Based Medicine and Clinical Research, Department of Epidemiology and Biostatistics, Beijing, China
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  • Hua Andrew Law,

    1. Johns Hopkins Bloomberg School of Public Health, Department of Epidemiology, Baltimore, Maryland, USA
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  • Ning-Li Wang

    Corresponding author
    1. Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing, China
    • Ning-Li Wang, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Laboratory, No.1 Dongijiaominxiang, Dongcheng District, Beijing, 100730, China.

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Myopia (near-sightedness or short-sightedness) is a condition in which the refractive power of the eye is greater than required. The most frequent complaint of people with myopia is blurred distance vision, which can be eliminated by conventional optical aids such as spectacles or contact lenses, or by refractive surgery procedures such as photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). PRK uses laser to remove the corneal stroma. Similar to PRK, LASEK first creates an epithelial flap and then replaces it after ablating the corneal stroma. The relative benefits and harms of LASEK and PRK, as shown in different trials, warrant a systematic review.


The objective of this review is to compare LASEK versus PRK for correction of myopia by evaluating their efficacy and safety in terms of postoperative uncorrected visual acuity, residual refractive error, and associated complications.

Search methods

We searched CENTRAL (which contains the Cochrane Eyes and Vision group Trials Register) (2015 Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to December 2015), EMBASE (January 1980 to December 2015), Latin American and Caribbean Health Sciences (LILACS) (January 1982 to December 2015), the ISRCTN registry (, ( and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) ( We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 15 December 2015. We used the Science Citation Index and searched the reference lists of the included trials to identify relevant trials for this review.

Selection criteria

We included in this review randomized controlled trials (RCTs) comparing LASEK versus PRK for correction of myopia. Trial participants were 18 years of age or older and had no co-existing ocular or systemic diseases that might affect refractive status or wound healing.

Data collection and analysis

Two review authors independently screened all reports and assessed the risk of bias of trials included in this review. We extracted data and summarized findings using risk ratios and mean differences. We used a random-effects model when we identified at least three trials, and we used a fixed-effect model when we found fewer than three trials.

Main results

We included 11 RCTs with a total of 428 participants 18 years of age or older with low to moderate myopia. These trials were conducted in the Czech Republic, Brazil, Italy, Iran, China, Korea, Mexico, Turkey, USA, and UK. Investigators of 10 out of 11 trials randomly assigned one eye of each participant to be treated with LASEK and the other with PRK, but did not perform paired-eye (matched) analysis. Because of differences in outcome measures and follow-up times among the included trials, few trials contributed data for many of the outcomes we analyzed for this review. Overall, we judged RCTs to be at unclear risk of bias due to poor reporting; however, because of imprecision, inconsistency, and potential reporting bias, we graded the quality of the evidence from very low to moderate for outcomes assessed in this review.

The proportion of eyes with uncorrected visual acuity of 20/20 or better at 12-month follow-up was comparable in LASEK and PRK groups (risk ratio (RR) 0.98, 95% confidence interval (95% CI) 0.92 to 1.05). Although the 95% CI suggests little to no difference in effect between groups, we judged the quality of the evidence to be low because only one trial reported this outcome (102 eyes). At 12 months post treatment, data from two trials suggest no difference or a possibly small effect in favor of PRK over LASEK for the proportion of eyes achieving ± 0.50 D of target refraction (RR 0.93, 95% CI 00.84 to 1.03; 152 eyes; low-quality evidence). At 12 months post treatment, one trial reported that one of 51 eyes in the LASEK group lost one line or more best-spectacle corrected visual acuity compared with none of 51 eyes in the PRK group (RR 3.00, 95% CI 0.13 to 71.96; very low-quality evidence).

Three trials reported adverse outcomes at 12 months of follow-up or longer. At 12 months post treatment, three trials reported corneal haze score; however, data were insufficient and were inconsistent among the trials, precluding meta-analysis. One trial reported little or no difference in corneal haze scores between groups; another trial reported that corneal haze scores were lower in the LASEK group than in the PRK group; and one trial did not report analyzable data to estimate a treatment effect. At 24 months post treatment, one trial reported a lower, but clinically unimportant, difference in corneal haze score for LASEK compared with PRK (MD -0.22, 95% CI -0.30 to -0.14; 184 eyes; low-quality evidence).

Authors' conclusions

Uncertainty surrounds differences in efficacy, accuracy, safety, and adverse effects between LASEK and PRK for eyes with low to moderate myopia. Future trials comparing LASEK versus PRK should follow reporting standards and follow correct analysis. Trial investigators should expand enrollment criteria to include participants with high myopia and should evaluate visual acuity, refraction, epithelial healing time, pain scores, and adverse events.


比較兩種矯正近視手術方法 ─ 雷射上皮細胞下角膜切除術 (LASEK) 與雷射屈光角膜切除術(PRK)


近視的成因是由於眼睛屈光度過大所導致的缺陷。近視的人最常困擾於遠處視野的視線模糊,通常的解決之道包含傳統的光學輔助工具配戴眼鏡、隱形眼鏡,或採取手術程序如雷射上皮細胞下角膜切除術 (LASEK) 與雷射屈光角膜切除術(PRK)予以矯正。PRK係以雷射去除角膜基質,與PRK方法類似,LASEK首先創建一個角膜上皮瓣,以雷射切除角膜基質,然後把此上皮細胞層放回。本系統回顧將來自各種不同試驗中報告的LASEK和PRK手術的利弊進行整理。


本文獻回顧目的為通過評估療效和安全性,包括術後裸眼視力、剩餘屈光不正以及其他相關併發症,來比較PRK 與LASEK 手術方法矯正近視。


我們搜索了CENTRAL(包含括Cochrane Eyes and Vision group臨床試驗註冊資料庫(2015年Issue 12),Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations,,Ovid MEDLINE Daily, Ovid OLDMEDLINE ( 1946 年 1 月至 2015 年 12 月),EMBASE(1980 年 1 月至 2015 年 12 月), Latin American and Caribbean Health Sciences(LILACS) (1982 年 1 月至 2015 年 12 月),ISRCTN 註冊資料庫 (, ( 和世界衛生組織 (WHO) International Clinical Trials Registry Platform (ICTRP) (。在電子搜索試驗時並未設定任何日期或語言限制。2015年12月15日為最後的電子資料庫搜尋日期。我們用科學引文索引(Science Citation Index) 來搜索納入試驗的參考文獻目錄以確認與本回顧相關的試驗。


本回顧中納入了比較PRK手術與LASEK手術矯正近視的隨機對照試驗 (RCTs)。受試者年齡均為18歲以上之成人,並無罹患其他可能影響屈光狀態或傷口癒合的眼部或全身性疾病。





LASEK 和PRK組於12個月後裸眼視力達到20/20甚至更好的比例相近(風險比(RR)0.98,95%信賴區間95% CI 0.92至1.05)。雖然95%CI顯示兩組間的效果從很小至沒有差異,​因僅有一個試驗報告此結果(102眼),判斷其證據品質低。由兩個試驗在接受治療12個月後的數據,受試眼達到± 0.50 D目標屈光度的比例並無差異或可能只有些微PRK優於LASEK效果。(RR 0.93,95%CI 0.84至1.03; 152眼;低證據品質),在接受治療12個月後,一個試驗提出在LASEK組別的51眼中,有ㄧ個的最佳眼鏡矯正視力失去視力表一行以上,相較於PRK組別的51眼中則無此情形發生(RR 3.00,95%CI 0.13至71.96;證據品質非常低)。

三個試驗在追蹤12個月或更久之後有不良結果。 在治療後的12個月,三個試驗報告角膜混濁分數; 然而,數據不足以及在這些試驗間不一致,排除了統合分析的可行性。一個試驗報告兩組間角膜混濁的分數差別極少或無差別;另一個試驗報告則指出,LASEK組別的角膜混濁分數平均比PRK組別低;而一試驗報告則並未提出可供評估療效的分析數據。在治療後24個月,一個試驗報告與PRK相比LASEK角膜混濁分數有較低但未達臨床意義差異(MD -0.22,95% CI -0.30 至-0.14,184眼,證據品質低)。





本翻譯計畫由臺北醫學大學考科藍臺灣研究中心(Cochrane Taiwan)、台灣實證醫學學會及東亞考科藍聯盟(EACA)統籌執行

Plain language summary

Two different surgical procedures for people who are near-sighted

Research question
How does laser-assisted subepithelial keratectomy compare with photorefractive keratectomy for eyes with myopia?

Myopia (short-sightedness or near-sightedness) is a condition whereby people cannot see distant objects clearly. The prevalence of myopia is increasing worldwide, especially in some Asian areas. Spectacles and contact lenses are commonly used for correction of this condition. Surgical procedures such as laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) also can be used for correction of myopia. In both procedures, a laser is used to remove corneal tissue (front of the eye); these procedures have been performed in human eyes for nearly 30 years.

Study characteristics
We identified 11 trials that enrolled 428 adult participants. These trials were conducted in various countries, including the Czech Republic, Brazil, Italy, Iran, China, Korea, Mexico, Turkey, USA, and UK. Ten out of 11 trials used a paired-eye design, in which one eye of each participant received LASEK and the other eye received PRK. The remaining trial included one eye of six participants and both eyes of 15 participants. Most participants included in the trials had low to moderate myopia. The evidence is current as of 15 December 2015.

Key results
Because these trials reported different outcomes at different time points, it is difficult to compare the effectiveness of LASEK versus PRK across trials. We assessed our primary outcomes 12 months after the surgeries were performed. Available data were insufficient to clarify whether LASEK performed better than PRK with respect to correcting visual acuity to 20/20 or better, achieving within 0.50 diopters of target refraction, or preventing loss of corrected visual acuity. Data were insufficient for assessment of whether differences between procedures in adverse outcomes occurred at 12 months after the surgeries. At 24 months post treatment, one trial reported that eyes treated LASEK with may have better corneal haze scores than those treated with PRK, but that the difference may not be noticeable.

Quality of the evidence
Available data were insufficient for investigation of whether LASEK or PRK is better at correcting near-sightedness. We judged the evidence for most outcomes as very low to moderate quality because of variation in reporting and differences in effects among trials.

Резюме на простом языке

Две разных хирургических процедуры для близоруких людей

Вопрос обзора
Каковы результаты сравнения лазерной субэпителиальной кератэктомии с фоторефракционной кератэктомией в коррекции миопии?

Миопией (или близорукостью) называют такое состояние, при котором человек не может ясно видеть отдаленные объекты. Распространённость миопии (близорукости) увеличивается по всему миру, особенно в некоторых регионах Азии. Для коррекции миопии обычно используют очки или контактные линзы. Кроме того, для коррекции могут быть использованы такие хирургические процедуры, как лазерная субэпителиальная кератэктомия (ЛАСЕК) и фоторефракционная кератэктомия (ФРК). В ходе этих процедур при помощи лазера снимается небольшой слой роговицы (передней части глаза); эти процедуры проводятся уже около 30 лет.

Характеристика исследований
Мы обнаружили 11 клинических испытаний, с общим числом участников - 428 взрослых человек. Эти испытания проводились в разных странах, включая: Чешскую республику, Бразилию, Италию, Иран, Китай, Корею, Мексику, Турцию, США и Великобританию. В 10 испытаниях из 11, использовался следующий метод сравнения: у каждого из участников один глаз был обработан при помощи ЛАСЕК, а другой - ФРК. В последнем исследовании у 6 участников провели процедуру с одним глазом, а у 15 других - с двумя. Большинство участников имели слабую или среднюю степень миопии. Эти доказательства актуальны по 15 декабря 2015 года.

Основные результаты
Сопоставить эффективность процедур ЛАСЕК и ФРК трудно, потому что клинические испытания сообщили о разных исходах в разные временные точки. Мы оценили наши первичные исходы спустя 12 месяцев после операций. Информации оказалось недостаточно, чтобы говорить о превосходстве процедуры ЛАСЕК над ФРК в отношении следующих показателей: коррекция остроты зрения до 20/20 или лучше, достижение необходимой рефракции с точностью до 0,50 диоптрий, предупреждение потери уже скорректированной остроты зрения. Данных было недостаточно и для оценки различия между процедурами по числу неблагоприятных исходов, проявившихся через 12 месяцев после операции. По прошествии 24 месяцев после лечения, в одном из испытаний показали: помутнение роговицы происходит реже после процедуры ЛАСЕК, но эта разница практически незаметна. 

Качество доказательств
Данных было недостаточно для разрешения вопроса о том, что эффективнее в коррекции близорукости - ЛАСЕК или ФРК. Качество большинства доказательств мы оценили от низкого до среднего. Это связанно с различиями при представлении отчетности и с разницей в величинах эффектов в испытаниях. 

Заметки по переводу

Перевод: Расческов Арсений Алексеевич. Редактирование: Зиганшина Лилия Евгеньевна. Координация проекта по переводу на русский язык: Cochrane Russia - Кокрейн Россия (филиал Северного Кокрейновского Центра на базе Казанского федерального университета). По вопросам, связанным с этим переводом, пожалуйста, обращайтесь к нам по адресу:

Laienverständliche Zusammenfassung

Vergleich von zwei verschiedenen chirurgischen Verfahren zur Korrektur von Kurzsichtigkeit

Wie ist die Wirksamkeit des Laser-Epithelial-Keratomileusis-Verfahrens im Vergleich zur photorefraktiven Keratektomie bei Kurzsichtigkeit?

Myopie (oder Kurzsichtigkeit) ist eine Form der Fehlsichtigkeit, bei der entfernte Objekte nicht scharf wahrgenommen werden können. Kurzsichtigkeit kommt weltweit immer häufiger vor, vor allem in einigen Teilen Asiens. Häufig kommen Kontaktlinsen und Brillen zum Einsatz, um eine Kurzsichtigkeit auszugleichen. Zur Korrektur der Myopie können auch chirurgische Operationen wie das Laser-Epithelial-Keratomileusis-Verfahren (LASEK) oder die photorefraktive Keratektomie (PRK) durchgeführt werden. Bei beiden Verfahren wird ein Laser eingesetzt, um Hornhautgewebe (Kornea, vorderer Teil des Augapfels) abzutragen; diese Operationen werden seit fast 30 Jahren beim Menschen durchgeführt.

Für diesen Review wurden elf Studien mit 428 erwachsenen Teilnehmern gefunden. Diese Studien wurden in verschiedenen Ländern durchgeführt, wie Tschechien, Brasilien, Italien, Iran, China, Korea, Mexiko, Türkei, USA und im Vereinigten Königreich. In zehn der elf Studien wurde ein Design angewandt, bei dem jeweils ein Auge der Probanden mit LASEK und das andere mit PRK behandelt wurde. Bei der elften Studie wurden bei sechs Teilnehmern nur ein Auge und bei 15 Probanden beide Augen operiert. Die meisten Teilnehmer dieser Studien hatten eine schwache bis mäßig starke Myopie. Die Evidenz ist auf dem Stand vom 15. Dezember 2015.

Da in den Studien verschiedene Endpunkte zu unterschiedlichen Zeitpunkten untersucht wurden, ist ein studienübergreifender Vergleich der Wirksamkeit von LASEK im Vergleich zu PRK schwierig. Wir untersuchten unsere primären Endpunkte zwölf Monate nach erfolgter Operation. Die verfügbaren Daten waren unzureichend, um eindeutig zu klären, ob mit dem LASEK-Verfahren bessere Ergebnisse erzielt wurden als mit PRK in Bezug auf eine Korrektur der Sehschärfe auf 20/20 oder besser, das Erreichen einer Zielrefraktion von maximal 0,5 Dioptrien oder die Vorbeugung eines Abfalls der korrigierten Sehschärfe. Die Daten waren nicht ausreichend, um daraus abzuleiten, ob Unterschiede in den Verfahren bezüglich negativer Folgen innerhalb von zwölf Monaten nach erfolgter Operation auftraten. Aus einer Studie ging hervor, dass Augen, die mit LASEK behandelt wurden, 24 Monate nach der Behandlung bessere Hornhauttrübungswerte aufweisen könnten als nach dem PRK-Verfahren operierte Augen; dieser Unterschied könnte jedoch nur geringfügig sein.

Qualität der Evidenz
Die verfügbaren Daten waren nicht ausreichend um festzustellen, ob LASEK oder PRK besser geeignet sind, um eine Kurzsichtigkeit zu korrigieren. Die Evidenz wurde aufgrund von Abweichungen in den dargestellten Inhalten und unterschiedlicher Wirkungen zwischen den Studien für die meisten Endpunkte als von sehr niedriger bis moderater Qualität eingestuft.

Anmerkungen zur Übersetzung

I. Noack, freigegeben durch Cochrane Schweiz.





我們檢視11個試驗共428位成年受試者。這些執行試驗所在的國家為 - 捷克共和國、巴西、義大利、伊朗、中國、韓國、墨西哥、土耳其、美國和英國。在11個的試驗中,有10個以成對眼(paired-eye)設計,即每位受試者的一眼接受LASEK,另一眼則接受PRK。其餘一個試驗則包括6位受試者的單一眼,以及15位病患的雙眼。試驗中大多數的受試者患有低至中度近視。證據更新溯至2015年12月15日。

因這些試驗在不同的時間點報告不同結果,使其不容易在各試驗中比較LASEK和PRK的效果。我們在各手術執行過後的12個月評估主要結果。取得的數據並不足以評估是否LASEK優於PRK: 矯正視力至20/20或更佳,達到0.50 屈光度之內的屈光目標,或預防已矯正視力的再度喪失。同樣由於數據的不足,無法評估在術後12個月,兩種手術程序之間是否存在不良結果上的差異。在其中一個試驗則指出於術後24個月,接受LASEK手術病眼的角膜混濁積分可能優於接受PRK手術病眼的積分,但差異可能並不顯著。




本翻譯計畫由臺北醫學大學考科藍臺灣研究中心(Cochrane Taiwan)、台灣實證醫學學會及東亞考科藍聯盟(EACA)統籌執行