***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 
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    Input: PURPOSE To compare 11  preschool vision screening tests  administered by licensed eye care professionals ( LEPs ; optometrists and pediatric ophthalmologists ) . DESIGN Multicenter , cross-sectional study . PARTICIPANTS A sample ( N = 2588 ) of 3- to 5-year-old children enrolled in Head Start was selected to over-represent children with vision problems . METHODS Certified LEPs administered 11 commonly used or commercially available screening tests . Results from a st and ardized comprehensive eye examination were used to classify children with respect to 4 targeted conditions : amblyopia , strabismus , significant refractive error , and unexplained reduced visual acuity ( VA ) . MAIN OUTCOME MEASURES Sensitivity for detecting children with > or = 1 targeted conditions at selected levels of specificity was the primary outcome measure . Sensitivity also was calculated for detecting conditions grouped into 3 levels of importance . RESULTS At 90 % specificity , sensitivities of noncycloplegic retinoscopy ( NCR )  ( 64 % ) , the  Retinomax Autorefractor  ( 63 % ) ,  SureSight Vision Screener ( 63 % ) , and Lea Symbols test ( 61 % ) were similar . Sensitivities of the Power Refractor II ( 54 % ) and HOTV VA test ( 54 % ) were similar to each other . Sensitivities of the R and om Dot E stereoacuity ( 42 % ) and Stereo Smile II ( 44 % ) tests were similar to each other and lower ( P<0.0001 ) than the sensitivities of NCR , the 2 autorefractors , and the Lea Symbols test . The cover-uncover test had very low sensitivity ( 16 % ) but very high specificity ( 98 % ) . Sensitivity for conditions considered the most important to detect was 80 % to 90 % for the 2 autorefractors and NCR . Central interpretations for the MTI and iScreen photoscreeners each yielded 94 % specificity and 37 % sensitivity . At 94 % specificity , the sensitivities were significantly better for NCR , the 2 autorefractors , and the Lea Symbols VA test than for the 2 photoscreeners for detecting > or = 1 targeted conditions and for detecting the most important conditions . CONCLUSIONS Screening tests administered by LEPs vary widely in performance . With 90 % specificity , the best tests detected only two thirds of children having > or = 1 targeted conditions , but nearly 90 % of children with the most important conditions . The 2 tests that use static photorefractive technology were less accurate than 3 tests that assess refractive error in other ways . These results have important implication s for screening preschool-aged children PURPOSE To assess the accuracy of the Lang II stereotest in screening for strabismus , amblyopia , and anisometropia in 6-year-old children . DESIGN Cross-sectional population -based study . METHODS The Sydney Myopia Study examined 1765 6-year-old children ( 78.9 % of eligible ) who were identified by r and om cluster sampling of 34 schools in Sydney , Australia . Sensitivity and specificity of the Lang II stereotest was determined by best stereoacuity .  Cycloplegic autorefraction , assessment of visual acuity , and ocular motility were conducted . RESULTS Test sensitivity ranged from 21.4 % for anisometropia ( > or = 1.0 diopter ) to 31.3 % for amblyopia . The detection rate for new cases of amblyopia ranged from 20 % to 40 % ; the detection rate for new cases of strabismus was 30 % . Specificity was > 98 % in all three conditions . Children with false-negative results included newly diagnosed cases of strabismus ( 14 of 25 children ) or amblyopia ( 5 of 12 children ) . CONCLUSION The Lang II stereotest , when used alone , has very limited value as a screening test of binocular dysfunction BACKGROUND The Enhanced Vision Screening Program is a population -based  vision screening program that has , at present , examined 59,782 children . Its main goal is to detect amblyopia , strabismus , and high refractive errors . An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly . The current study determines the negative predictive value of the screening program : For a subject having passed the vision screening test , what is the probability of not having amblyopia , strabismus , or high refractive errors ? METHODS Of the 11,734 subjects who passed the vision screening , 200 were r and omly chosen to undergo a strictly defined gold st and ard examination by an orthoptist and an ophthalmologist .  RESULTS Of the 200 r and omly chosen subjects , 157 underwent the gold st and ard evaluation . The negative predictive value of the Enhanced Vision Screening Program was 97.6 % for any potentially vision-threatening ocular condition . It was 98.7 % if we considered only the visually significant ocular problems that the test was design ed to detect . CONCLUSION Because the negative predictive value of the Enhanced Vision Screening Program is not 100 % , some children with amblyopia , strabismus , or refractive errors are missed . Occasionally , a rare , potentially vision-threatening condition may go undetected . Parents should be made aware of this when they receive the results of the vision screening Purpose . To compare the agreement between subjective refraction and autorefraction using two commercially available autorefractors . Methods . Prospect i ve data were collected for 190 subjects using either the Nidek ARK-700A ( Fremont , CA ) or the Topcon KR-8000  ( Paramus , NJ ) and subjective refraction ( masked to autorefraction ) . Refractions were compared in terms of spherical equivalent using Bl and -Altman limits of agreement and astigmatic vector difference using median and 95th percentile . Results . The two groups were similar for age , gender , spherical equivalent , and astigmatic power . The differences in spherical equivalent between subjective and autorefraction were significantly different ( mean ± SD ; Nidek , −0.03 ± 0.36 D ; Topcon , + 0.11 ± 0.34 D ; analysis of variance , F = 7.84 ; p < 0.01 ) . However , the 95 % limits of agreement were similar : Nidek , −0.74 to + 0.68 D ; Topcon , −0.55 to + 0.77 D. The median differences in astigmatic vector difference were also similar : Nidek , 0.27 D and Topcon , 0.25 D. However , the 95th percentile was 0.67 D for Nidek and 1.09 D for Topcon . There was a low frequency of large ( > 1.00 D ) differences in spherical equivalent , 1.1 % with each autorefractor . There were five cases with astigmatic vector difference > 1 D , all with the Topcon KR-8000 ( 5.3 % ) . Conclusions . Both autorefractors show excellent agreement with subjective refraction . Despite a statistically significant difference in mean spherical equivalent ( 0.14 D ) , near identical limits of agreement ( 0.10 D difference ) suggest clinical equivalence . Conversely , for astigmatism , despite similar median scores , major outliers were more likely with the Topcon , reflected in a 0.42 D larger 95th percentile , which suggests a small advantage for the Nidek for avoiding large astigmatic errors The aim of the study is to examine the suitability of the Lang II R and om Dot Stereotest for use by district nurses in primary healthcare centres . The Lang Stereotest is an inexpensive method . It is easy to apply , but the child 's co-operation is required . Approximately 100 district nurses were given detailed information and instruction by an orthoptist prior to a r and omized population -based community trial initiated in 1993 . In the county of Uppsala in Sweden , all 4293 children born in 1990 were r and omized to one of the following four study groups : intervention , control , reliability or validity . All children were followed from birth to 6.5 y of age with respect to the occurrence of strabismus . The kappa statistic for test-retest reliability among district nurses was 0.65 ( 95 % CI , 0.51 - 0.80 ) . A validation of the outcomes of district nurses ' against orthoptists ' examinations using the Lang Stereotest showed a sensitivity of 0.33 ( 95 % CI , 0.09 - 0.65 ) and a specificity of 0.85 ( 0.80 - 0.89 ) . Of 113 cases of strabismus , 53 % were detected within the first 3 y of life . Examination of 1132 3-y-old children using the Lang Stereotest enabled the district nurses to detect 11 new cases of strabismus . Only one of these cases was referred to an orthoptist as a direct consequence of the screening . The Lang Stereotest showed low reliability and low validity in this community trial . It is concluded that the Lang II R and om Dot Stereotest is not suitable for the screening of manifest strabismus in unselected population s of 3-y-old children in Sweden , where a large proportion of cases of strabismus is detected during the first 3 y of life BACKGROUND New , small-target ( < 1 degree ) r and om dot stereogram ( STRDS ) and binocular suppression ( STBS ) tests appropriate for preschool vision screening were developed to correct the shortcomings of previous such tests , particularly missed cases of anisometropic amblyopia such as found with some RDS-based testing . METHODS In Experiment 1 , the tests were administered to 14 patients with current or a recent history of moderate ( < or = 20/60 ) anisometropic amblyopia , or with accommodative esotropia or monofixation syndrome . All subjects had good binocularity ( < or = 100 " contour stereoacuity ) . In Experiment 2 , the new tests were administered in a screening setting to a group of 112 three- to five-year-olds to determine testability .  Visual acuity , cover testing , and photoscreening  were administered as control measures . RESULTS In Experiment 1 , eleven of the 14 patients failed both tests . Two anisometropic amblyopes passing one or both tests had an acuity < or = 20/30 in the worse eye and < or = 25 " stereoacuity . Three anisometropic amblyopia patients failing the STRDS passed another RDS test with similar disparity but a larger target size , confirming a report34 that anisometropic amblyopes may pass RDS testing with parafoveal stereopsis despite the presence of central suppression . The STRDS and STBS tests indicated 80 % and 96 % specificity , respectively , with the original method ologies ; STRDS specificity increased to 95 % with retesting with a different methodology . Administration time was 30 sec to 60 sec per test . CONCLUSION Small-target RDS or suppression testing may be more effective for strabismus and amblyopia screening of preschoolers than previous RDS test formats AIMS To test the effectiveness of a PC computer program for detecting vision disorders which could be used by non-trained personnel , and to determine the prevalence of visual impairment in a sample population of preschool children in the city of Beer-Sheba , Israel . METHODS 292 preschool children , aged 4–6 years , were examined in the kindergarten setting , using the computer system and “ gold st and ard ” tests .  Visual acuity and stereopsis were tested and compared using Snellen type symbol charts and r and om dot stereograms respectively . The sensitivity , specificity , positive predictive value , negative predictive value , and kappa test were evaluated . A computer pseudo Worth four dot test  was also performed but could not be compared with the st and ard Worth four dot test owing to the inability of many children to count . RESULTS Agreement between computer and gold st and ard tests was 83 % and 97.3 % for visual acuity and stereopsis respectively . The sensitivity of the computer stereogram  was only 50 % , but it had a specificity of 98.9 % , whereas the sensitivity and specificity of the visual acuity test were 81.5 % and 83 % respectively . The positive predictive value of both tests was about 63 % . 27.7 % of children tested had a visual acuity of 6/12 or less and stereopsis was absent in 28 % using st and ard tests . Impairment of fusion was found in 5 % of children using the computer pseudo Worth four dot test . CONCLUSIONS The computer program was found to be stimulating , rapid , and easy to perform . The wide availability of computers in schools and at home allow it to be used as an additional screening tool by non-trained personnel , such as teachers and parents , but it is not a replacement for st and ard testing OBJECTIVE To assess the effectiveness of the Otago photoscreener in detecting  amblyogenic factors in the general population . DESIGN Prospect i ve clinical trial . SETTING Suburban school district in Delta , BC . PARTICIPANTS A total of 1245 kindergarten children . INTERVENTIONS Screening for visual defects was done with the Otago photoscreener ( by a technician ) and the regular manual method ( by a health care aide ) . A st and ard ophthalmologic 
    Output:
    
Conclusion Diagnostic test accuracy of preschool vision screening tests can only be sufficiently investigated after establishing age-related values defining amblyopia , refractive errors and binocular disorders .