***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 results of wavefront-guided custom LASIK and the Toric Implantable Collamer Lens ( TICL ) in the correction of myopic astigmatism . METHODS This observational , non-r and omized study compared clinical efficacy results from the TICL 's US Food and Drug Administration Clinical Trial and published Summaries of Safety and Effectiveness of two wavefront-guided lasers : STAR S4 CustomVue excimer laser system ( VISX Inc ) and LADARVision4000 CustomCornea excimer laser system ( Alcon Laboratories Inc ) . Preoperative myopic refractive error was divided into two groups : -3.00 to -7.00 diopters ( D ) and -7.00 to -11.00 D. RESULTS The percentage of  eyes with uncorrected visual acuity ( UCVA ) of 20/20 and 20/40 and predictability of manifest refraction spherical equivalent within + /- 0.50 and + /- 1.00 D in the three groups was similar with only one statistically significant difference ( TICL versus Alcon within + /- 1.00 D : 97 % versus 82 % ; P = .008 ) . The TICL had significantly better postoperative best spectacle-corrected visual acuity ( BSCVA ) compared to preoperative BSCVA than both the VISX CustomVue and Alcon CustomCornea ( P < .001 ) . The TICL  postoperative UCVA outcomes compared to preoperative BSCVA were significantly better than Alcon CustomCornea outcomes ( P < .001 ) . Additionally , almost half ( 48 % ) of the TICL cases had improvement in postoperative UCVA compared to preoperative BSCVA , whereas only 23 % of the Alcon CustomCornea eyes showed improvement . CONCLUSIONS Although comparable in clinical efficacy outcomes , the TICL had a significantly better postoperative improvement in BSCVA and significantly better postoperative UCVA than preoperative BSCVA . The TICL can be considered as an alternative to LASIK through the full range of use PURPOSE To evaluate the 3- to 4-year effects of the Implantable Contact Lens ( ICL ) on the corneal endothelium . SETTING Multicenter study . METHODS Noncontact specular microscopy was performed as a subgroup study in a Phase III U.S. Food and Drug Administration clinical trial . Endothelial cell images were collected in the central region of the cornea before surgery and 3 , 12 , 24 , and 36 months after surgery , with a few at 48 months . The images were recorded and analyzed later by a central reading center . The cell density , coefficient of variation , and percentage of hexagonal cells were determined . RESULTS The cumulative endothelial cell loss was between 8.4 % and 8.9 % over the first 3 years and between 8.4 % and 9.5 % over the first 4 years depending on the method of calculation . The cell loss between baseline and 3 months was 2.1 % ; 3 months and 1 year , 0.9 % ; 1 year and 2 years , 2.3 % ; 2 years and 3 years , 3.2 % ; and 3 years and 4 years , -0.1 % . The coefficient of variation decreased over the course of the study , and the proportion of cases with hexagonal cells increased slightly . CONCLUSIONS The cell loss between 1 year and 3 years in the absence of an increase in the coefficient of variation and /or a decrease in the percentage of hexagonal cells is most readily explained by prolonged corneal remodeling following the surgical procedure rather than ongoing cell loss . The cell loss observed between 3 years and 4 years ( 0.1 % gain ) was negligible . Regardless of the cause of the change in endothelial cell density over the first 3 years , the available 4-year data suggest there was no ongoing chronic loss OBJECTIVE To evaluate the safety , efficacy , predictability , and long-term stability of the Artisan Phakic Intraocular Lens ( Ophtec BV , Groningen , the Netherl and s ) for the correction of high myopia . METHODS Prospect i ve analysis of 26 eyes from 15 patients who underwent placement of the Artisan lens for the correction of high and extreme myopia . The mean ( SD ) preoperative spherical equivalent was - 12.30 ( 2.69 ) diopters ( D ) ( range , - 17.25 to - 8.25 D ) . RESULTS At 5 years , the mean ( SD ) manifest refraction was - 0.37 ( 0.69 ) D , with 95 % of eyes within 1 D of attempted correction and 74 % of eyes within 0.5 D of the attempted correction . Ninety-five percent of eyes achieved an uncorrected visual acuity of 20/40 or better and 74 % achieved an uncorrected visual acuity of 20/20 or better . No eyes experienced a loss of 1 or more lines of best-corrected visual acuity . Sixteen percent of eyes gained 2 or more lines of best-corrected visual acuity . From preoperative measurements , the mean endothelial cell density decreased by 14.05 % at 5 years postoperatively . CONCLUSIONS Placement of the Artisan lens is predictable , stable , and effective at reducing high and extreme myopia 5 years after implantation . The rate of endothelial cell loss was significantly higher than has been reported in previous studies Purpose : To compare the results of laser-assisted in situ keratomileusis ( LASIK ) and implantable collamer lenses ( ICL ) in the correction of myopia -4 to -7.88 D. Methods : A total of 1678 LASIK eyes from the Davis Duehr Eye Center , Madison , WI , and 144 ICL eyes from the 14-site US FDA Clinical Trial for ICL for Myopia were compared . Both series were concurrently operated on with 4 to 7.88 D of preoperative spherical equivalent of the manifest refraction and were examined at 1 day , 1 week , 1 month , and 6 months postoperatively . The mean baseline myopia was slightly higher in the ICL group ( ICL : −6.4 ± 1.1 D ; LASIK : −5.6 ± 1.1 D ) . Best spectacle-corrected visual acuity ( BSCVA ) , uncorrected visual acuity ( UCVA ) , and refractions were collected prospect ively in both series . Results : BSCVA loss of at least 2 lines was significantly higher in the LASIK series in the early healing period ( 1 week : 6 % vs. 0.7 % ; P = 0.008 ) , whereas a BSCVA gain of at least 2 lines was statistically better with the ICL at 1 ( 5 % vs. 0.9 % , P = 0.001 ) and 6 months ( 4 % vs. 0.8 % , P = 0.013 ) . Proportion of cases seeing 20/15 or better uncorrected ( 21.6 % vs. 7.8 % , P < 0.001 ) and 20/20 or better ( 67 % vs. 57 % , P = 0.027 ) at 6 months postoperatively was better in the ICL group .  The ICL was statistically more predictable ( attempted vs. achieved ) at 6 months ; ±0.50 D ( 79 % ICL vs. 70 % LASIK , P = 0.034 ) and ±1.0 D ( 97 % ICL vs. 88 % LASIK , P < 0.001 ) . Stability was achieved ( 95 % ≤ 1.0 D ) at the 1-week to 1-month interval for both groups ( 95 % LASIK ; 98 % ICL ) . The stability of refraction ( ≤0.5 D change ) was significantly better in the ICL group than the LASIK group through 6 months . No serious complications occurred in either series . Conclusions : The ICL was safer and more effective than LASIK and seems to be a viable alternative to corneal refractive excimer surgery in the treatment of low myopia PURPOSE To assess the safety and efficacy of the Implantable Contact Lens ( ICL ) to treat moderate to high myopia . DESIGN Prospect i ve nonr and omized clinical trial . PARTICIPANTS Five hundred twenty-three eyes of 291 patients with between 3 and 20.0 diopters ( D ) of myopia participating in the U. S. Food and Drug Administration clinical trial of the ICL for myopia . INTERVENTION Implantation of the ICL . MAIN OUTCOME MEASURES Uncorrected visual acuity ( UCVA ) , refraction , best spectacle-corrected visual acuity ( BSCVA ) , adverse events , operative and postoperative complications , lens opacity analysis ( Lens Opacity Classification System III ) , subjective satisfaction , and symptoms . RESULTS Twelve months postoperatively , 60.1 % of patients had a visual acuity of 20/20 or better , and 92.5 % had an uncorrected visual acuity of 20/40 or better . Patients averaged a 10.31-line improvement in UCVA , 61.6 % of patients were within 0.5 D , and 84.7 % were within 1.0 D of predicted refraction . Only one case ( 0.2 % ) lost > 2 lines of BSCVA . Gains of 2 or more lines of BSCVA occurred in 55 cases ( 11.8 % ) at 6 months and 41 cases ( 9.6 % ) at 1 year after ICL surgery . Early and largely asymptomatic , presumably surgically induced anterior subcapsular ( AS ) opacities were seen in 11 cases ( 2.1 % ) ; an additional early AS opacity ( 0.2 % ) was seen because of inadvertent anterior chamber irrigation of preservative-containing solution at surgery . Two ( 0.4 % ) late ( > or = 1 year postoperatively ) AS opacities were observed . Two ( 0.4 % ) ICL removals with cataract extraction and intraocular lens implantation have been performed . Patient satisfaction ( very/extremely satisfied ) was reported by 92.4 % of subjects on the subjective question naire ; only four patients ( 1.0 % ) reported dissatisfaction . Slightly more patients reported an improvement at 1 year over baseline values for the following subjective symptoms : quality of vision , glare , double vision , and night driving difficulties . Only a 3 % difference between pre-ICL and post-ICL surgery was reported for haloes . CONCLUSIONS The results support the safety , efficacy , and predictability of ICL implantation to treat moderate to high myopia 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 PURPOSE To compare matched population s of  LASIK  and Visian Implantable Collamer Lens ( ICL )  cases in the correction of myopia between -3.00 and -7.88 diopters ( D ) . METHODS One hundred sixty-four LASIK eyes with prospect i ve data collected from a single center and 164 ICL eyes from the multicenter US ICL Clinical Trial were compared in this observational non-r and omized study . The LASIK and ICL groups were well matched for age , gender , and mean level of preoperative spherical equivalent refraction . RESULTS At 6 months , best spectacle-corrected visual acuity ( BSCVA ) > or = 20/20 was 85 % with LASIK and 95 % with ICL ( P = .003 ) compared to preoperative values of 93 % and 88 % , respectively ( P 
    Output:
    
Both HTAs concluded that there was good evidence of the short-term efficacy and safety of pIOLs , however , their conclusions regarding long-term safety differed .
The 2006 HTA found convincing evidence of long-term safety , while the 2009 HTA found no long-term evidence about the risks of complications including cataract development , corneal damage , and retinal detachment .
The systematic review of adverse events found that cataract development ( incidence rate of 9.6 % of eyes ) is a substantial risk following posterior chamber pIOL implantation , while chronic endothelial cell loss is a safety concern after iris-fixated pIOL implantation .
Adverse event rates varied by lens type , but they were more common in eyes that received posterior chamber pIOLs .
At most time points , more than 50 % of eyes achieved a MRSE within ± 0.5 D of emmetropia and at least 85 % within ± 1.0 D. Predictability was lower for eyes with more severe preoperative refractive errors .
Safety , defined as a loss of two or more Snellen lines of best spectacle corrected visual acuity ( BSCVA ) , was high for all refractive errors and lens types .
The studies that compared pIOLs with LASIK , PRK , and CLE for patients with moderate to high myopia and myopic astigmatism showed that pIOLs performed better than these alternative surgical options for the outcomes of : UCVA , predictability and stability of MRSE , postoperative MRSE , safety ( measured as clinical ly significant loss of BSCVA ) , and gains in BSCVA.Correction of refractive cylinder ( astigmatism ) was the only outcome that favoured refractive surgery over pIOLs .
This was observed for both toric and non-toric pIOLs ( toric pIOLs correct for astigmatism , non-toric pIOLs do not ) .
Common adverse events in the LASIK groups were diffuse lamellar keratitis and striae in the corneal flap .
In the pIOL groups , lens repositioning and lens opacities ( both asymptomatic and visually significant cataracts ) were the most commonly observed adverse events .