***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 : To compare the higher‐order aberrations ( HOAs ) in 70 eyes ( 38 patients ) that had wavefront‐guided laser in situ keratomileusis ( LASIK ) with those in 70 eyes ( 40 patients ) that had wavefront‐guided laser‐assisted subepithelial keratectomy ( LASEK ) for the treatment of myopia . SETTING : Department of Ophthalmology , Yonsei University College of Medicine , Myongdong Bal‐geun sesang Eye Clinic , and Seran Eye Center , Seoul , Korea . METHODS : In a prospect i ve study , 140 consecutive eyes of 78 patients were treated with wavefront‐guided LASIK or LASEK  according to the patient 's choice after each procedure had been thoroughly explained . The patients were followed for 6 months . Best corrected visual acuity ( BCVA ) , uncorrected visual acuity ( UCVA ) , manifest refraction , and wavefront aberrations were measured at baseline and 1 , 3 , and 6 months after surgery . RESULTS : There were no significant differences in postoperative BCVA , UCVA , and manifest refraction between groups . The mean root‐mean‐square wavefront error of HOAs for a scotopic pupil in the wavefront‐guided LASIK group was significantly smaller than that in the wavefront‐guided LASEK group at 1 month . Analyzing individual Zernike coefficients , the spherical aberration and second coma were significantly smaller in the wavefront‐guided LASIK group than in the wavefront‐guided LASEK group at 1 month . This difference in HOAs between groups disappeared at 3 and 6 months . CONCLUSIONS : The HOAs in the scotopic condition were not different between the wavefront‐guided LASIK and LASEK groups beginning 3 months after surgery . However , the HOAs in the LASIK and LASEK groups had a different time course , especially in the case of spherical aberration . This finding suggests that postoperative changes in aberration contribute to the final outcome of wavefront‐guided ablation PURPOSE To compare the visual and refractive outcomes of laser epithelial keratomileusis ( LASEK ) and laser in situ keratomileusis ( LASIK ) for the treatment of low to moderate myopia . DESIGN Retrospective , nonr and omized , control-matched study . METHODS The charts of 2257 eyes that underwent LASEK or LASIK treatment were review ed . Patients who were 21 years of age or older having between -0.75 and -6.00 diopters ( D ) of myopia with up to -2.25 D of astigmatism were included . One hundred twenty-two LASEK-treated eyes were matched with 122 LASIK-treated eyes having preoperative spheres , cylinders , and spherical equivalent ( SE ) within + /-0.50 D. Both groups had similar preoperative best spectacle-corrected visual acuity ( BSCVA ) , laser platform , and follow-up duration s. Outcome measures were visual and refractive results . RESULTS Preoperatively , the mean SE was -3.50 + /- 1.40 D for LASEK and -3.50 + /- 1.42 D for LASIK ( P = .59 ) . Postoperatively , the mean logarithm of minimum angle of resolution ( logMAR ) uncorrected visual acuity ( UCVA ) was 0.01 + /- 0.08 ( 20/21 ) for LASEK and 0.06 + /- 0.12 ( 20/23 ) for LASIK ; the mean SE was -0.15 + /- 0.40 D for LASEK and -0.37 + /- 0.45 D for LASIK ; and the mean logMAR of BSCVA was -0.03 + /- 0.06 ( 20/19 ) for LASEK and -0.02 + /- 0.05 ( 20/19 ) for LASIK . No eye lost 2 or more lines of BSCVA in both groups . CONCLUSIONS Slight differences in the visual and refractive results between LASEK and LASIK were observed , despite the use of the same nomogram . Both procedures were safe , effective , and predictable . Nomogram adjustment may be necessary for LASIK surgeons adopting surface ablation Aim : To compare 1-year follow-up results of photorefractive keratectomy ( PRK ) with mitomycin C ( MMC ) and laser in situ keratomileusis ( LASIK ) for custom correction of myopia . Methods : Eighty-eight eyes of 44 patients with moderate myopia were r and omised to PRK with 0.002 % MMC for 1 min in one eye and LASIK in the fellow eye . The 1-year follow-up was evaluated . Results : There were no differences between LASIK and MMC-PRK eyes preoperatively . Forty-two patients completed the 1-year follow-up . MMC-PRK eyes achieved better uncorrected visual acuity ( p = 0.03 ) and better best-spectacle-corrected visual acuity ( p<0.001 ) 1 year after surgery . SE did not differ in the two groups during follow-up ( p = 0.12 ) . Clinical ly significant haze was not found in surface ablation eyes . LASIK eyes showed a greater higher-order aberration ( p = 0.01 ) and lower contrast sensitivity ( p<0.05 ) than MMC-PRK eyes postoperatively . Excellent vision was reported in 64 % of LASIK and 74 % of MMC-PRK eyes 1 year after surgery . The corneal resistance factor and corneal hysteresis ( ORA , Reichert ) were higher in LASIK than in MMC-PRK eyes ( p<0.01 ) at the last follow-up . Conclusions : Wavefront-guided PRK with 0.002 % MMC was more effective than wavefront-guided LASIK for correction of moderate myopia . Further research is necessary to determine the optimal concentration , exposure time and long-term corneal side effect of MMC PURPOSE To compare visual and refractive results , contrast sensitivity , and tear stability after laser in situ keratomileusis ( LASIK )  in one eye and laser epithelial keratomileusis ( LASEK ) in the fellow eye for low myopia . METHODS Patients diagnosed with low myopia , with a maximum difference of 1 D between their two eyes , were r and omly assigned to receive LASEK on one eye and LASIK on the other eye . A total of 64 eyes of 32 patients with a mean age of 26.83 + /- 5.33 years were included in the study . Preoperative myopia ranged from -1.00 to -6.00 D. Follow-up was 6 to 12 months . Uncorrected ( UCVA ) and best spectacle-corrected visual acuity ( BSCVA ) , Schirmer test results , tear break-up time , corneal asphericity , corneal uniformity index , predicted corneal acuity , and contrast sensitivity values were compared with preoperative values . A Wilcoxon test was used for statistical comparisons and a P-value less than .05 was considered significant . RESULTS At 6 months after surgery , there was no statistically significant difference in UCVA , BSCVA , spherical and cylindrical refractive error , Schirmer test , or tear break-up time between groups . Contrast sensitivity values in the LASIK eyes were lower in comparison to preoperative values , but there was no change in the LASEK group . CONCLUSIONS Based on 6-month results , LASEK for low myopia was safe and effective with predictable results , offered early refractive stability , and may be considered an alternative for LASIK Purpose : To compare changes in anterior corneal wavefront aberrations after myopic laser‐assisted subepithelial keratectomy ( LASEK ) and laser in situ keratomileusis ( LASIK ) .  Setting : Institute of Ophthalmology , Catholic University , Rome , Italy . Methods : This prospect i ve study included 36 eyes of 25 myopic patients : 18 eyes of 12 patients had LASEK and 18 eyes of 13 patients , LASIK .  The topography data ( CSO EyeMap , version 6.2 ) were used to calculate corneal aberrations with 3.0 mm and 7.0 mm pupils before and 3 months after surgery . Results : Total corneal aberrations increased similarly after LASEK and LASIK with the 7.0 mm pupil but did not change with the 3.0 mm pupil . Coma‐like and spherical‐like aberrations changed similarly after both procedures , but spherical‐like aberrations increased after LASEK with the 3.0 mm pupil ( P<.05 , independent t test ) . With the 7.0 mm pupil , the amount of achieved correction was positively correlated with changes in total corneal aberrations after LASIK ( P = .007 ) and with spherical‐like aberrations after LASEK ( P = .03 ) and LASIK ( P<.003 ) . Although there was no significant difference between LASEK and LASIK ( P>.05 , independent t test ) , in individual eyes with an achieved correction less than 7.50 diopters ( D ) , spherical‐like aberrations increased more after LASEK than after LASIK . Conclusions : In this preliminary study , myopic LASEK and LASIK  changed total and higher‐order corneal aberrations . In both procedures , changes in spherical‐like aberrations were dependent on the achieved correction . However , in individual eyes , spherical‐like aberrations increased more after LASEK than after LASIK for low‐moderate achieved correction , suggesting that these procedures may induce the same optical changes in the anterior corneal surface in different ways PURPOSE To compare the refractive results of laser epithelial keratomileusis ( LASEK ) and laser in situ keratomileusis ( LASIK ) for the correction of low myopia . METHODS A prospect i ve , interventional , non-r and omized , observer-masked study was performed of patients with myopia of < or = -2.50 diopters ( D ) ( cylinder < or = 1.50 D ) who had undergone either LASEK or LASIK .  Refractive analysis was performed by a masked observer preoperatively and 1 day , 1 week , and 1 and 3 months postoperatively . RESULTS Seventy-nine eyes that fulfilled the inclusion criteria in each group were included in the study . No statistically significant differences were noted in age , gender , or preoperative refractive error between groups . Postoperative uncorrected visual acuity ( UCVA ) was significantly lower in LASEK eyes 1 and 7 days postoperatively ( P = .0001 ) . At 1 and 3 months postoperatively , no significant differences were noted between the groups in UCVA ( P = .07 ) , but best spectacle-corrected visual acuity 3 months postoperatively was significantly better in LASEK eyes ( P = .01 ) . The refractive error was similar in both groups ( P = .3 ) . CONCLUSIONS Visual improvement after LASEK for low myopia is significantly slower than after LASIK . Visual outcomes at 3 months postoperatively were similar with both techniques for the correction of low myopia PURPOSE To compare laser epithelial keratomileusis ( LASEK ) and LASIK for the correction of high myopia . METHODS A prospect i ve , single-masked study was conducted . Patients treated with LASEK to correct myopia > or = -7.00 diopters ( D ) ( spherical equivalent manifest refraction ) with a cylinder < or = -3.50 D ( LASEK group ) were compared to patients treated with LASIK ( LASIK group )  using the same excimer laser ( Technolas 217C ) . Mitomycin C ( MMC ) 0.02 % was applied for 1 minute in all LASEK-treated eyes . RESULTS A total of 228 consecutive eyes were included in the study ( 114 in each group , matched for preoperative refraction ) . The mean preoperative spherical equivalent manifest refraction was -8.72 + /- 1.20 D in the LASEK group and -8.74 + /- 1.20 D in the LASIK group ( range : -7.00 to -13.75 D ) ( P = .9 ) . Uncorrected visual acuity ( UCVA ) was significantly lower in LASEK eyes 1 , 7 , and 30 days postoperatively ( P = .0001 for each comparison ) . No significant differences were found at 3 months postoperatively in UCVA ( P = .3 ) , best spectacle-corrected visual acuity ( BSCVA ) ( P = .2 ) , or in the safety ( P = .6 ) and efficacy ( P = .8 ) indices . Uncorrected visual acuity was 1.0 or better in 34.2 % of LASEK eyes and 44.7 % of LASIK eyes . Spherical refraction was + 0.25 + /- 0.6 D after LASEK and -0.06 + /- 0.5 D after LASIK ( P = .0001 ) . Sixty-eight percent of LASEK eyes and 79 % of LASIK eyes were within + /- 0.50 D of intended refraction . No LASEK eye versus 7 LASIK eyes lost 2 lines of BSCVA . Eight LASEK eyes gained 2 or more lines of BSCVA versus 1 LASIK eye . CONCLUSIONS Visual improvement after LASEK with intraoperative MMC was significantly slower than after LASIK . Visual outcomes ( UCVA , BSCVA , and safety and efficacy indices ) 3 months after surgery were similar with both techniques for the correction of high myopia . Ten percent 
    Output:
    
There were no significant differences in visual and refractive outcomes between the two surgeries for low to moderate myopia .
The incidence of loss of ≥1 line of BCVA was significantly higher in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup .
The efficacy ( MRSE and UCVA ) of LASEK appeared to be a significant worsening trend in the long-term followup .
Corneal haze was more severe in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup .
The flap-related complications still occurred in LASIK , but the incidence was not significantly higher than that in LASEK .
LASEK and LASIK  were safe and effective for low to moderate myopia .
The advantage of LASEK was the absence of flap-related complications , and such procedure complication may occur in LASIK and affect the visual results .
The increased incidence of stromal haze and regression in LASEK significantly affected the visual and refractive results for high myopia