***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 assess visual outcome in four groups : one multifocal intraocular lens ( IOL ) , one monofocal IOL , and two phakic , one older and one younger . Setting : Department of Ophthalmology , National Health Service , Puerta de Hierro University Clinic , Madrid , Spain . Methods : This prospect i ve study comprised 70 aphakic eyes , 42 with a multifocal and 28 with a monofocal IOL , and 42 phakic eyes , 21 older than 60 years and 21 younger than 60 years . The phakic groups served as a double control . Main outcome measures were corrected and uncorrected distance and near visual acuities , contrast and glare sensitivity , and clinical and subjective complications . Results : There were no significant differences between the monofocal and multifocal IOL groups in uncorrected or corrected distance visual acuity . Near visual acuity in the multifocal group , with and without distance correction , was significantly better than in the monofocal group . Near vision with addition was similar between the two IOL groups . There were no significant differences between the monofocal and multifocal IOL groups in contrast sensitivity at the 96 and 50 % thresholds . Between‐group differences of less than one Regan line were found at the 25 and 11 thresholds . The phakic groups had better contrast sensitivity . The older phakic group ’s results were closer to those of the IOL groups . There were no significant complications . Conclusion : Distance acuity and contrast sensitivity were similar in the monofocal and multifocal IOL groups ; however , the multifocal group had significantly better near acuity . The younger phakic group had significantly better contrast sensitivity than the other groups OBJECTIVE Two million cataract extraction s are performed annually in the United States . The procedure is nearly always accompanied by implantation of a monofocal intraocular lens ( IOL ) , which corrects the patient 's distance vision . The authors ' objective was to measure visual function and quality -of-life outcomes associated with bilateral implantation of a multifocal IOL , which corrects distance and near vision , and to compare the outcomes with those of the st and ard therapy . DESIGN A prospect i ve , r and omized , double-masked , clinical trial was conducted at eight sites in the United States , seven sites in Germany , and one site in Austria . PARTICIPANTS Participants included 245 cataract patients , 127 of whom received the multifocal IOL bilaterally and 118 of whom received a monofocal IOL of nearly identical construction bilaterally . METHODS Clinical data included visual acuity ( VA ) , complications , and adverse events . Quality -of-life data were collected using a previously vali date d survey instrument at baseline , after first eye surgery , and after second eye surgery . RESULTS At 3 months after surgery , patients who had received multifocal IOLs had significantly better uncorrected and distance corrected binocular near VA compared with patients who had received monofocal IOLs ( mean uncorrected VA , 20/26 multifocal vs. 20/40 monofocal ; mean distance corrected VA , 20/28 multifocal vs. 20/45 monofocal ; P < 0.0001 ) . Additionally , 96 % of patients who had received multifocal IOLs and 65 % of patients who had received monofocal IOLs achieved both 20/40 and J3 ( Jaeger ) or better uncorrected , binocular distance and near visual acuities ( P < 0 . 0001 ) . Patients who had received multifocal IOLs were more likely than patients who had received monofocal IOLs to never wear glasses overall ( 32 % multifocal vs. 8 % monofocal ; P < 0.0001 ) . On a 4-point scale , patients who had received multifocal IOLs on average reported having between " a little bit " and " some " glare or halo , whereas patients who had received monofocal IOLs reported between " none " and " a little bit " of glare or halo ( 1.57 vs. 0.43 ; P < 0.001 ) . Patients who had received multifocal IOLs rated their vision without glasses better overall at near and at intermediate distances ( P < or = 0.002 ) and demonstrated better visual function for near tasks and social activities . CONCLUSIONS Cataract patients who received multifocal IOLs at time of surgery obtained better uncorrected and distance corrected near VA and reported better overall vision , less limitation in visual function , less spectacle dependency , and more glare or halo than those who received traditional monofocal IOLs Aims To evaluate the functional effect of bilateral implantation of two different multifocal intraocular lenses ( IOL ) compared with the st and ard monofocal IOL . Methods Sixty-nine patients were recruited into a prospect i ve , double-masked , r and omised , controlled trial at a single hospital in the United Kingdom . Sixty completed follow-up ; 16 implanted with  monofocal IOLs  , 29 with AMO ’ ARRAY ’ multifocal IOLs and 15 with Storz ’ TRUEVISTA ’ bifocal IOLs . Phacoemulsification and IOL implantation was performed to a st and ardised technique in both eyes within a 2-month period . The main outcome measures were distance and near visual acuity , depth of field and vali date d assessment of subjective function ( TyPE question naire ) . Results Unaided distance acuity was good , and equivalent across the three groups . Corrected distance acuity was significantly lower in the bifocal group . Patients with multifocal and bifocal IOLs could read smaller absolute print size than those in the monofocal group ( P = 0.05 ) , but at a closer reading distance such that mean unaided near acuity was equal in the three groups . Corrected near acuity was significantly higher in the monofocal control group ( P < 0.05 ) . Depth of field was increased in multifocal ( P = 0.06 ) and bifocal ( P = 0.004 ) groups . Overall visual satisfaction was equal in the three groups , while near visual satisfaction was higher in the multifocal group than the monofocal ( P = 0.04 ) . Spectacle independence was not seen in the monofocal group , but was achieved in 28 % of multifocal IOL patients and 33 % of bifocal patients ( P < 0.001 ) . Adverse symptoms such as glare and haloes were significantly more bothersome with multifocal ( not bifocal ) IOLs than monofocals ( P = 0.01 ) . Conclusions Multifocal and bifocal IOLs  improved unaided near vision performance , with around one in three patients becoming spectacle-independent . The main adverse effect was an increased incidence of subjective glare and haloes in the multifocal IOL group OBJECTIVE The objective of the report is to examine the comparative effectiveness and cost-effectiveness of various intraocular lenses ( IOLs ) for the treatment of  age-related cataracts .  CLINICAL NEED TARGET POPULATION AND CONDITION A cataract is a hardening and clouding of the normally transparent crystalline lens that may result in a progressive loss of vision depending on its size , location and density . The condition is typically bilateral , seriously compromises visual acuity and contrast sensitivity and increases glare . Cataracts can also affect people at any age , however , they usually occur as a part of the natural aging process . The occurrence of cataracts increases with age from about 12 % at age 50 years , to 60 % at age 70 . In general , approximately 50 % of people 65 year of age or older have cataracts . Mild cataracts can be treated with a change in prescription glasses , while more serious symptoms are treated by surgical removal of the cataract and implantation of an IOL . In Ontario , the estimated prevalence of  cataracts increased from 697,000 in 1992 to 947,000 in 2004 ( 35.9 % increase , 2.4 % annual increase ) . The number of cataract surgeries per 1,000 individuals at risk of cataract increased from 64.6 in 1992 to 140.4 in 1997 ( 61.9 % increase , 10.1 % annual increase ) and continued to steadily increase to 115.7 in 2004 ( 10.7 % increase , 5.2 % increase per year ) . DESCRIPTION OF TECHNOLOGY/THERAPY IOLs are classified either as monofocal , multifocal , or accommodative . Traditionally , monofocal ( i.e .. fixed focusing power ) IOLs are available as replacement lenses but their implantation can cause a loss of the eye 's accommodative capability ( which allows variable focusing ) . Patients thus usually require eyeglasses after surgery for reading and near vision tasks . Multifocal IOLs aim to improve near and distant vision and obviate the need for glasses . Potential disadvantages include reduced contrast sensitivity , halos around lights and glare . Accommodating IOLs are design ed to move with ciliary body contraction during accommodation and , therefore , offer a continuous range of vision ( i.e. near , intermediate and distant vision ) without the need for glasses . Purported advantages over multifocal IOLs include the avoidance of haloes and no reduction in contrast sensitivity .  Polymethyl methacrylate ( PMMA ) was the first material used in the fabrication of IOLs and has inherent ultraviolet blocking abilities . PMMA IOLs are inflexible , however , and require a larger incision for implantation compared with newer foldable silicone ( hydrophobic ) and acrylic ( hydrophobic or hydrophilic ) lenses . IOLs can be further sub-classified as being either aspheric or spheric , blue/violet filtered or non-filtered or 1- or 3-piece . METHODS OF EVIDENCE -BASED ANALYSIS : A literature search was conducted from January 2003 to January 2009 that included OVID MEDLINE , MEDLINE In-Process and Other Non-Indexed Citations , EMBASE , the Cumulative Index to Nursing & Allied Health Literature ( CINAHL ) , The Cochrane Library , and the International Agency for Health Technology Assessment /Centre for Review and Dissemination . Inclusion Criteria Exclusion Criteria adult patients with age-related cataracts systematic review s , r and omized controlled trials ( RCTs ) PRIMARY OUTCOMES distance visual acuity ( best corrected distance visual acuity ) , near visual acuity ( best distance corrected near visual acuity ) SECONDARY OUTCOMES contrast sensitivity , depth of field , glare , quality of life , visual function , spectacle dependence , posterior capsule opacification .  studies with fewer than 20 eyesIOLs for non-age related cataractsIOLs for presbyopia studies with a mean follow-up < 6months studies reporting insufficient data for analysis COMPARISONS OF INTEREST : The primary comparison of interest was accommodative vs. multifocal vs. monofocal lenses . Secondary comparisons of interest included : tinted vs. non-tinted lensesaspheric vs. spheric lensesmultipiece vs. single piece lensesbio material A ( e.g. acrylic ) vs. bio material B ( e.g. silicone ) lensessharp vs. round edged lensesThe quality of the studies was examined according to the GRADE Working Group criteria for grading quality of evidence for interventional procedures . SUMMARY OF FINDINGS The conclusions of the systematic review of IOLs for age-related cataracts are summarized in Executive Summary Table 1 . CONSIDERATIONS FOR THE ONTARIO HEALTH SYSTEM : Procedures for crystalline lens removal and IOL insertion are insured and listed in the Ontario Schedule of Benefits .If a particular lens is determined to be medically necessary for a patient , the cost of the lens is covered by the hospital budget . If the patient chooses a lens that has enhanced features , then the hospital may choose to charge an additional amount above the cost of the usual lens offered . An IOL manufacturer stated that monofocal lenses comprise approximately 95 % of IOL sales in Ontario and premium lenses ( e.g. , multifocal/accomodative ) consist of about 5 % of IOL sales . A medical consultant stated that all types of lenses are currently being used in Ontario ( e.g. , multifocal , monofocal , accommodative , tinted , nontinted , spheric , and aspheric ) . Nonfoldable lenses , rarely used in routine cases , are primarily used for complicated cataract implantation situations . ES Table 1 : Conclusions for the Systematic Review of IOLs for Age-Related CataractsComparison Conclusion GRADE Quality Multifocal vs. monofocal Objective Outcomes Significant improvement in BDCUNVANo significant difference in BCDVAInconclusive evidence for contrast sensitivityInconclusive evidence for glareSubjective Outcomes Inconclusive evidence for visual satisfactionSignificant increase in glare/halosSignificant increase in freedom from spectaclesmoderatemoderatelowvery lowlowlow/moderatelow/moderateAccommodative vs. multifocal/monofocalInconclusive due to Insufficient limited evidence for any effectiveness outcome very lowHydrophilic acrylic vs. other material s ( hydrophobic acrylic , silicone)Significant increase in PCO scoreLowSharp edged compared to round edgedSignificant reduction in PCO scoreLowOne piece compared to three pieceNo significant difference in PCO scorelowHydrophobic acrylic compared to siliconeNo significant difference in PCO scoremoderateAspherical modified prolate anterior surface compared to sphericalNo significant difference in VASignificant reduction in contrast sensitivityvery lowvery lowBlue light filtering compared to non blue-light filteringNo significant difference in BCDVANo significant difference in contrast sensitivityNo significant difference in HRQLlow 
    Output:
    
Results Multifocal lenses achieved higher rates of spectacle independence compared to monofocal lenses but also had higher reported frequency of dysphotopsia and worse contrast sensitivity , especially with low light or glare .
Accommodative lenses were not associated with reduced contrast sensitivity or more dysphotopsia but had only modest improvements in spectacle independence compared to monofocal lenses .
Studies of monovision did not target a sufficiently myopic outcome in the near-vision eye to achieve the full potential for spectacle independence .
Patients reported high levels of overall satisfaction regardless of implanted IOL .
No studies correlated patient-reported outcomes with patient expectations .