***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE Evaluation of night glare after  excimer laser in situ keratomileusis ( LASIK )  using two different ablation zone diameters . METHODS One hundred and twenty eyes of 60 consecutive myopic patients received LASIK with the Nidek EC-5000 excimer laser .  Eyes were r and omized so that every patient had a single ablation zone of 5.5 mm on one eye and an ablation zone of 5.5 mm with a transition zone of 1.0 mm diameter larger on the other eye . Night glare was measured by two methods ; a spot light test and a subjective question naire . RESULTS At 6 months , 54 patients ( 90 % ) were examined ; results of the spot light test showed that 40 patients ( 74.1 % ) perceived more glare with the eye with the single ablation zone ; the subjective question naire indicated that 22 patients ( 40.7 % ) had more night glare with the eye with a single ablation zone compared to the other eye . The use of the transition zone increased the required total ablation depth by 20 % . CONCLUSION The use of a peripheral transition 1.0 mm diameter larger than the ablation zone significantly decreased night glare after LASIK with slight increase in the required central ablation depth OBJECTIVE To determine the incidence and severity of complications from laser in situ keratomileusis ( LASIK ) for the correction of myopia by experienced and inexperienced surgeons . DESIGN Prospect i ve , observational clinical study . PARTICIPANTS Fourteen surgeons and 1062 eyes of 574 myopic patients who desired surgical correction of myopia ranging from -2.00 to -22.50 diopters ( D ; mean , -7.57 D ) and astigmatism no greater than 4.00 D participated in this study . INTERVENTION Myopia was corrected with LASIK . Astigmatism was corrected with arcuate keratotomy at the same time as the initial procedure or subsequently . MAIN OUTCOME MEASURES Primary outcome measures were change in best spectacle-corrected visual acuity ( BSCVA ) and the incidence of complications . RESULTS Eyes were followed for a mean of 9.5 months after their last surgical procedure ( range , 2 weeks-21 months ) . Three hundred eighty-one eyes ( 36 % ) underwent 468 enhancement procedures 3 months or more after the initial treatment . There were 27 ( 2.1 % ) intraoperative and 40 ( 3.1 % ) postoperative complications .  Laser ablation was not performed during the initial treatment of 17 ( 1.6 % ) eyes because of intraoperative complications . Seventy-four eyes gained 2 or more lines of BSCVA , while 50 eyes lost 2 or more lines of BSCVA . Only three eyes lost two or more lines of BSCVA to a level worse than 20/40 . One eye with a flap buttonhole ( BSCVA 20/50 ) also had an epiretinal membrane . The second eye ( BSCVA 20/60 ) had a flap buttonhole that may have been related to a previous corneal transplant . The third eye ( -22.50 D before surgery ) had a rhegmatogenous retinal detachment develop , reducing BSCVA from 20/60 to 20/200 . The incidence of intraoperative complications decreased from 3.1 % during the first 3 months to 0.7 % during the last 9 months of the study ( P = 0.02 ) . CONCLUSIONS LASIK is acceptably safe for the correction of myopia . Although complications occur in approximately 5 % of cases , these rarely lead to visual loss of more than two Snellen lines and postoperative acuity below 20/40 . Flap buttonholes were more likely to cause loss of BSCVA than free or incomplete flaps ( P = 0.02 ) ; flap buttonholes may be more likely in eyes that have undergone previous surgery . Complication rates can be reduced as the surgical team gains experience OBJECTIVE The research ers sought to assess whether the widely used 1994 Cochrane Highly Sensitive Search Strategy ( HSSS ) for r and omized controlled trials ( RCTs ) in MEDLINE could be improved in terms of sensitivity , precision , or parsimony . METHODS A gold st and ard of 1,347 RCT records and a comparison group of 2,400 non-trials were r and omly selected from MEDLINE .  Terms occurring in at least 1 % of RCT records were identified . Fifty percent of the RCT and comparison group records were r and omly selected , and the ability of the terms to discriminate RCTs from non-trial records was determined using logistic regression . The best performing combinations of terms were tested on the remaining records and in MEDLINE . RESULTS The best discriminating term was " Clinical Trial " ( Publication Type ) . In years where the Cochrane assessment of MEDLINE records had taken place , the strategies identified few additional unindexed records of trials . In years where Cochrane assessment has yet to take place , " R and omized Controlled Trial " ( Publication Type ) proved highly sensitive and precise . Adding six more search terms identified further , unindexed trials at reasonable levels of precision and with sensitivity almost equal to the Cochrane HSSS . CONCLUSIONS Most reports of RCTs in MEDLINE can now be identified easily using " R and omized Controlled Trial " ( Publication Type ) . More sensitive search es can be achieved by a brief strategy , the Centre for Review s and Dissemination/Cochrane Highly Sensitive Search Strategy ( 2005 revision ) 
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However there is a low risk of developing early cataract with phakic IOLs .
Phakic IOL surgery appears to result in better contrast sensitivity than excimer laser correction for moderate to high myopia .
The results of this review suggest that phakic IOLs are safer than excimer laser surgical correction for moderate to high myopia in the range of -6.0 to -20.0 D and phakic IOLs are preferred by patients .