***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 compare refractive performance and safety of laser in situ keratomileusis ( LASIK ) and Artisan phakic intraocular lens ( PIOL ) for moderately high myopia . DESIGN A prospect i ve , r and omized trial with paired eye control . PARTICIPANTS Twenty-five patients with myopia ranging from -8.00 to -12.00 diopters ( D ) . INTERVENTION For each patient , one eye received LASIK and the other one was implanted with an Artisan phakic intraocular lens . The treated eye and the surgical technique were r and omized . MAIN OUTCOME MEASURES Primary outcome measure was spherical equivalent refraction . Main secondary outcome measures were the change of two or more lines and safety index ( ratio postoperative to preoperative best-corrected visual acuity ) . RESULTS One year after surgery , the mean spherical equivalent refraction was -0.74 + /- 0.67 D for LASIK-treated eyes and -0.95 + /- 0.45 D for Artisan-treated eyes , and the majority of LASIK-treated eyes ( 64 % ) and Artisan-treated eyes ( 60 % ) were within + /-1.00 D of the intended result . At 1 month , the mean spherical equivalent refraction was -0.28 + /- 0.71 D for LASIK and -1.07 + /- 0.59 D for Artisan ( P < 0.01 ) . The changes of two or more lines were in favor of Artisan ( P < 0.05 ) . The safety index was significantly better for Artisan ( 1.12 + /- 0.21 ) than for LASIK ( 0.99 + /- 0.17 ) at 1 year ( P < 0.02 ) . CONCLUSIONS In cases of moderately high myopia , LASIK and Artisan phakic intraocular lenses seemed to produce a similar predictability . The best-corrected visual acuity and subjective evaluation of quality of vision were better for Artisan Purpose . To compare the results of laser assisted in situ keratomileusis ( LASIK ) and implantable contact lenses ( ICL ) in the correction of moderate/high myopia . Methods . Five hundred fifty-nine LASIK eyes from the Davis Duehr Eye Center , Madison , WI , and 210 ICL eyes from the 14-site U.S. FDA Clinical Trial for ICL for Myopia were compared . These series were concurrently operated on with 8 to 12 D of preoperative myopia and were examined at 1 day , 1 week , 1 month , 6 months , and 1 year postoperatively . The mean baseline myopia was slightly higher in the ICL group , ( ICL : −9.8 ± 1.7 D ; LASIK : −9.1 ± 0.97 D ) . BSCVA , UCVA , and refractions were collected prospect ively in both series . Results . Every index of BSCVA , UCVA , predictability of refraction , and stability of refraction studied favored the ICL over the LASIK procedure . All but one of the indices ( UCVA % 20/40 or better ) were statistically significant in at least half of the time periods studied . At 6-month follow-up , both the loss of two or more lines  ( ICL : 0 % ; LASIK : 2%;p = 0.05 ) and gain of two or more lines ( ICL : 7 % ; LASIK : 3%;p = 0.04 ) of BSCVA were better with the ICL . Similarly , efficacy outcomes with the ICL were better with predictability ( attempted versus achieved ±1.0 D ) of the ICL at 90 % ; 76 % with LASIK ( p < 0.001 ) . In this highly myopic series , UCVA 20/20 or better was 50 % with ICL compared with 35 % with LASIK ( p < 0.001 ) . No serious complications occurred in either series of cases . Conclusions . The ICL was safer and more effective than LASIK and appears to be a viable alternative to corneal refractive excimer surgery in the treatment of moderate to high myopia 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 This study evaluated the predictability , stability , and safety of laser in situ keratomileusis ( LASIK ) in myopia and myopic astigmatism . DESIGN The study design was a prospect i ve , unmasked , nonr and omized clinical trial . PARTICIPANTS Participating were 25 patients with myopia ( 37 eyes ) with astigmatism of less than 1.00 diopter ( D ) , divided into 3 subgroups ( -5.00 to -9.90 D , 8 eyes ; -10.00 to -14.90 D , 10 eyes ; -15.00 to -29.00 D , 19 eyes ) , and 37 patients with myopia ( 56 eyes ) with corneal astigmatism of 1.00 to 4.50 D , divided into 3 subgroups ( -5.00 to -9.90 D , 12 eyes ; -10.00 to -14.90 D , 24 eyes ; -15.00 to -29.00 D , 20 eyes ) . INTERVENTION LASIK was performed using the Automatic Corneal Shaper and the Keracor 116 excimer laser . MAIN OUTCOME MEASURES Visual acuity , manifest refraction , central corneal isl and s , ablation decentration , and patient satisfaction were measured . RESULTS At 12 months , predictability , regression between 1 and 12 months , uncorrected visual acuity ( UCVA ) , loss of two or more lines of corrected visual acuity , and patient satisfaction of the spherical ( toric ) groups are reported . Subgroups -5.00 to -9.90 D : 100 % ( 75 % ) + 1.00 D ; regression less than or equal to 1.00 D in 100 % ( 91.7 % ) ; UCVA greater than or equal to 20/40 in 87.5 % ( 70 % ) ; none lost two or more lines ; 100 % ( 84 % ) highly satisfied . Subgroups -10.00 to -14.90 D : 60 % ( 78.3 % ) + /-1.00 D ; regression less than or equal to 1.00 D in 100 % ( 87 % ) ; UCVA greater than or equal to 20/40 in 77.8 % ( 86.4 % ) ; 10 % ( 4.3 % ) lost two lines ; 90 % ( 91 % ) highly satisfied . Subgroups -15.00 to -29.00 D : 38.9 % ( 21.4 % ) + /-1.00 D ; regression less than or equal to 1.00 D in 72.2 % ( 64.3 % ) ; UCVA greater than or equal to 20/40 in 33.3 % ( 40 % ) ; 5.6 % ( 7.1 % ) lost two lines ; 78 % ( 50 % ) highly satisfied . Differences of predictability and change of manifest refraction between subgroups of -5.00 to -9.90 D and -15.00 to -29.00 D were statistically significant . Central isl and s ( decentrations ) were observed in 17 % ( 5.6 % ) of eyes of the spherical and in 16 % ( 4.1 % ) of the toric group . Overall , the corneal interface was visible in 8.2 % . CONCLUSIONS The LASIK method used in this study showed stability of manifest refraction and adequate uncorrected central visual acuity in a large percentage of patients with myopia up to -15.00 D. Corneal stability was not as uniform . Central corneal isl and s were observed in a sizable minority of patients despite pretreatment . For myopia greater than 15.00 D , accuracy and patient satisfaction were sufficiently poor to advise against using the authors ' treatment technique in these groups . Visually significant microkeratome and laser-related problems were noted in a smaller percentage of patients . Patients with astigmatism correction were less pleased with results than were patients who received spherical corrections PURPOSE To compare visual , refractive , and clinical outcomes of foldable iris-fixated phakic intraocular lens ( PIOL ) implantation versus femtosecond laser-assisted LASIK for myopia between -6.00 and -9.00 diopters ( D ) . METHODS Forty-six myopic patients were r and omized to undergo bilateral Artiflex ( Ophtec BV ) PIOL implantation or bilateral femtosecond laser-assisted conventional LASIK with the VISX S2 ( Abbott Medical Optics ) . Refraction , uncorrected ( UDVA ) and corrected ( CDVA ) distance visual acuity , contrast sensitivity , corneal endothelial cell count , rate of retreatment , and complications were compared . RESULTS Twelve months after surgery , no statistically significant differences were noted in spherical equivalent refraction ( P=.19 ) or UDVA ( P=.28 ) , whereas CDVA was better in the PIOL group ( P<.001 ) . Spherical equivalent refraction was within ±0.50 D in 42 ( 91.3 % ) LASIK eyes and 41 ( 89.1 % ) PIOL eyes ( P>.99 ) . The percentage of eyes gaining lines of CDVA was significantly higher in the PIOL group ( 50.0 % vs 8.7 % ; P<.001 ) . Contrast sensitivity was better for PIOL eyes at 1.5 cycles per degree 
    Output:
    
Phakic IOL surgery was safer than excimer laser surgical correction for moderate to high myopia as it results in significantly less loss of best spectacle corrected visual acuity ( BSCVA ) at 12 months postoperatively .
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 .
Phakic IOL surgery also scored more highly on patient satisfaction/preference question naires .
The results of this review suggest that , at one year post surgery , 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 .
While phakic IOLs might be accepted clinical practice for higher levels of myopia ( greater than or equal to 7.0 D of myopic spherical equivalent with or without astigmatism ) , it may be worth considering phakic IOL treatment over excimer laser correction for more moderate levels of myopia ( less than or equal to 7.0 D of myopic spherical equivalent with or without astigmatism ) .