Meta analysis of randomized controlled clinical trial in the effect of hinge location on dry eye syndrome after LASIK / 中华实验眼科杂志

ABSTRACT

Background Dry eye syndrome is a frequent postoperative complication of laser in situ keratomileusis (LASIK).Some studies reported that the hinge location of corneal flap has influence on dry eye syndrome following LASIK,but others showed inverse views.Objective This systematic review was to evaluate and compare the effects of a superior-and nasal/temporal-hinge location on dry eye syndrome after LASIK.Methods A systematic literature retrieval was conducted in the Medline,Embase,Cochrane Library and CNKI from 1990 to 2011 according to designed searching strategy and relevant words.Published randomized-controlled clinical trial (RCT) data of the effect of superior-and nasal/temporal-hinge location on dry eye syndrome were extracted by two researchers separately.The outcome parameters,such as tear film breakup time (BUT),Schirmer Ⅰ test and corneal sensation were analyzed 1 week,3 months and 6-12 months postoperatively.The statistical analysis was performed using a RevMan 5.0 software and the quality of included literatures were graded according to the Jadad scale.Fixedeffect model was used for the inhomogeneity multiple studies (P≥0.1,homogeneity test I2 ＜50％),and random-effect model was used for the homogeneity studies.Results Ten pieces RCT papers were searched and 3 of them were rejected because of the lack of outcome data.In 7 included studies,652 eyes of 331 patients were involved in the Meta analysis,with the Jadad scores ≥ 3.BUT assessment was performed in 5 trials (530 eyes),Schirmer Ⅰ test evaluation was in 7 trials (652 eyes) and corneal sensation observation was in 4 trials (320 eyes),without significant homogeneity among the relevant literature(I2＜50％).Meta analysis revealed that BUT in the eyes with superior-hinge group was obvious shorter than that in the eyes nasal/temporal-hinge group at 1 week (WMD =-0.42,95％ CI-0.79 to-0.06,P=0.020),but there was no signifieant difference in 3 months and 6-12 months duration postoperatively.Better corneal sensation was found at postoperative 3 months (WMD=-0.62,95％CI-l.09 to-0.19,P=0.005) in the nasal/temporal-hinge group,but there was no difference in 1 week and 6-12 months duration postoperatively.No significant difference was seen between the two groups in Schirmer Ⅰ test during the follow-up period (P＞0.05).Conclusions LASIK with nasal/temporal-hinge corneal flap can improve the corneal sensation and relief the dry eye syndrome after LASIK to some extent.More high-quality evidence-based studies are still needed for the further clinical evaluation.