***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 Dry eye syndrome ( DES ) is believed to be one of the most common ocular problems in the United States ( US ) , particularly among older women . However , there are few studies describing the magnitude of the problem in women and how this may vary with demographic characteristics . DESIGN Cross-sectional prevalence survey . METHODS STUDY POPULATION we surveyed 39,876 US women participating in the Women 's Health Study about a history of diagnosed DES and dry eye symptoms . MAIN OUTCOME MEASURE we defined DES as the presence of clinical ly diagnosed DES or severe symptoms ( both dryness and irritation constantly or often ) . We calculated the age-specific prevalence of DES and adjusted the overall prevalence to the age distribution of women in the US population . We used logistic regression to examine associations between DES and other demographic factors . RESULTS The prevalence of DES increased with age , from 5.7 % among women < 50 years old to 9.8 % among women aged > or = 75 years old . The age-adjusted prevalence of DES was 7.8 % , or 3.23 million women aged > or = 50 in the US . Compared with Whites , Hispanic ( odds ratio [ OR ] = 1.81 , confidence interval [ CI ] = 1.18 - 2.80 ) and Asian ( OR = 1.77 , CI = 1.17 - 2.69 ) women were more likely to report severe symptoms , but not clinical ly diagnosed DES . There were no significant differences by income ( P([trend ] ) = .78 ) , but more educated women were less likely to have DES ( P([trend ] ) = .03 ) . Women from the South had the highest prevalence of DES , though the magnitude of geographic differences was modest . CONCLUSIONS Dry eye syndrome leading to a clinical diagnosis or severe symptoms is prevalent , affecting over 3.2 million American women middle-aged and older . Although the condition is more prevalent among older women , it also affects many women in their 40s and 50s . Further research is needed to better underst and DES and its impact on public health and quality of life Objective .The objective of this work was to develop a psychometrically sound question naire for measuring the on-the-job impact of chronic health problems and /or treatment ( “ work limitations ” ) . Research Design .Three pilot studies ( focus groups , cognitive interviews , and an alternate forms test ) generated c and i date items , dimensions , and response scales . Two field trials tested the psychometric performance of the question naire ( studies 1 and 2 ) . To test recall error , study 1 subjects were r and omly assigned to 2 different question naire groups , a question naire with a 4-week reporting period completed once or a 2-week version completed twice . Responses were compared with data from concurrent work limitation diaries ( the gold st and ard ) . To test construct validity , we compared question naire scores of patients with those of healthy job-matched control subjects . Study 2 was a cross-sectional mail survey testing scale reliability and construct validity . Subjects . The study subjects were employed individuals ( 18–64 years of age ) from several chronic condition groups ( study 1 , n = 48 ; study 2 , n = 121 ) and , in study 1 , 17 healthy matched control subjects . Measures . Study 1 included the assigned question naires and weekly diaries . Study 2 included the new question naire , SF-36 , and work productivity loss items . Results .In study 1 , question naire responses were consistent with diary data but were most highly correlated with the most recent week . Patients had significantly higher ( worse ) limitation scores than control subjects . In study 2 , 4 scales from a 25-item question naire achieved Cronbach alphas of ≥0.90 and correlated with health status and self-reported work productivity in the hypothesized manner ( P ≤0.05 ) . Conclusions .With 25 items , 4 dimensions ( limitations h and ling time , physical , mental-interpersonal , and output dem and s ) , and a 2-week reporting period , the Work Limitations Question naire demonstrated high reliability and validity Background This study was performed to estimate the annual direct cost incurred by dry eye patients , which includes expenses for treatment and drugs , as well as the cost of punctal plugs . Methods The study group consisted of 118 dry eye patients aged 20 years or older who visited any of the 15 medical care facilities that participated in this prospect i ve cohort dry eye study . We estimated annual direct costs from outpatient medical records and survey question naires obtained from patients . Results Of the total patients enrolled , 10 were men and 108 women , and their average age was 64.1 ± 11.2 years . The number of hospital visits made by patients was 5.8 ± 3.6 per year . Among those who used ophthalmic solutions , the numbers of bottles used per year were as follows : 32.1 ± 20.8 bottles of hyaluronic acid ophthalmic solution ( 87 patients ) , 53.1 ± 42.2 bottles of artificial tears ( 40 patients ) , and 33.2 ± 23.2 bottles of over-the-counter eyedrops ( 15 patients ) . In patients with punctal plugs , 4.1 ± 3.9 plugs were used annually . The annual drug cost was 32,000 ± 21,675 Japanese yen ( 323 ± 219 US dollars ) . The clinical cost was 16,318 ± 9961 Japanese yen ( 165 ± 101 US dollars ) . The total direct costs including punctal plug treatment amounted to 52,467 ± 38,052 Japanese yen ( 530 ± 384 US dollars ) . Conclusion Although treatment modalities for dry eye in Japan were different from those in the US and in European countries , the direct cost of dry eye patients in Japan was comparable with that reported in those countries . Considering the high prevalence of dry eye , the direct cost of this chronic condition may be significant Purpose To study the prevalence and associations of dry eye symptoms in adult Chinese . Methods The Beijing Eye Study is a population -based study in northern China , which included 4439 of 5324 subjects invited to participate with an age of 40 + years ( response rate : 83.4 % ) . For the present study , a r and om sample was taken consisting of 1957(44.1 % ) subjects ( 1112 women ; 56.9 % ) .  Dry eye symptoms were evaluated with ( 1 ) an  interviewer-assisted question naire ; ( 2 )  measurement of the tear-film break-up time ; ( 3 ) assessment of the fluorescein staining of the cornea ; ( 4 ) slit-lamp-based examination of a meibomian gl and dysfunction ;  and ( 5 ) Schirmer 's test .  Results Symptoms of a dry eye felt ‘ often ’ or ‘ at all times ’ were present in 411 subjects ( 21.0 % ) . In a multivariate analysis , dry eye symptoms were significantly associated with age ( P<0.001 ) , female gender ( P<0.001 ; odds ratio ( OR ) : 1.56 ; 95 % confidence intervals ( CI ) : 1.23 , 1.98 ) , urban region ( P<0.001;OR : 1.89 ; 95 % CI : 1.46 , 2.48 ) , low degree of nuclear cataract ( P=0.02 ) , and undercorrection of refractive error ( P=0.005 ; OR : 1.42 ; 95 % CI : 1.11 , 1.82 ) . All tests for dry eye did not vary significantly between the dry eye group and the normal group . Conclusions The dry eye symptoms as evaluated subjectively in a question naire occurred in about 21 % of the adult population in China , with associations to age , female gender , urban region , and undercorrection of a refractive error . Measurement of the tear-film break-up time , assessment of the corneal fluorescein staining , slit-lamp-based examination of a meibomian gl and dysfunction , and Schirmer 's test were not significantly associated with dry eye symptoms PURPOSE To investigate the prevalence of and risk factors associated with  dry eye syndrome ( DES ) in South Korea . DESIGN Cross-sectional study . METHODS In 2010 and 2011 , 11,666 subjects , ranging in age from 19 to 95 , were r and omly selected as nationally representative participants in the Korea National Health and Nutrition Examination Survey ( KNHANES ) . Subjects were divided into 2 groups : 1 with clinical ly  diagnosed DES and 1 with symptoms of dry eye . We determined the prevalence of and risk factors for dry eyes in a Korean population .  Health-related quality of life ( HRQoL ) , measured by the EuroQoL-5 dimension ( EQ-5D )  , was evaluated in patients with dry eyes . RESULTS The mean age was 49.9 years . The overall prevalence of diagnosed DES was 8.0 % ( 95 % confidence interval [ CI ] , 7.3 % to 8.7 % ) , and of dry eye symptoms the prevalence was 14.4 % ( 95 % CI , 13.1 to 15.7 ) . Age ( adjusted odds ratio [ aOR ] = 1.8 , 1.6 ) , female ( aOR = 2.8 , 1.9 ) ; history of eye surgery ( aOR = 2.6 , 2.2 ) ; stress ( aOR = 1.7 , 1.6 ) ; thyroid disease ( aOR = 1.7 , 1.5 ) ; and high education level ( aOR = 1.6 , 1.5 ) were common risk factors in the groups . Subjects who had undergone ptosis , cataract or refractive surgery were more likely to have dry eye than subjects with no history of eye surgery . Means of pain and anxiety dimensions in the EQ-5D and the Euro Quality of Life Visual Analog Scale ( EQ-VAS ) were significantly higher in the group with diagnosed DES than in the normal group . CONCLUSIONS The risk factors were mostly similar in both groups . It is thought there are more patients with DES who have not been diagnosed by doctors . Doctors should identify whether a patient has any risk factors for dry eye . Patients need to be educated about the modifiable factors of DES OBJECTIVE To evaluate the prevalence of and risk factors for dry eye disease ( DED ) in an elderly Korean population . METHODS This population -based study in Yongin , Korea , included 657 individuals 65 years or older r and omly selected from an official household registration data base .  Dry eye symptoms were assessed using a 6-item question naire , and DED was defined as having 1 or more dry eye symptoms often or all the time .  Dry eye tests  , including the Schirmer test , tear film break-up time measured using fluorescein , cornea fluorescein staining , and examination for meibomian gl and dysfunction  , were performed . RESULTS The crude prevalence of DED was 30.3 % , and the age- , sex- , and region ( urban vs rural)-adjusted prevalence was 33.2 % . Women ( P = .01 ) and urban dwellers ( P = .001 ) were more likely to have DED . Of those with DED , 85.1 % had tear film break-up time of 10 seconds or less , 54.1 % had meibomian gl and dysfunction , 39.2 % had a fluorescein score of 1 or greater , and 32.8 % had a Schirmer test score of 5 mm or less . A low Schirmer score was correlated with increased prevalence of DED , although sensitivity was low . CONCLUSIONS Dry eye disease is common in elderly Koreans ; female sex and living in an urban region were strongly correlated with its frequency . We also noted a positive correlation between low Schirmer test scores and symptom-based DED OBJECTIVE To investigate the prevalence of dry eye in population s equal or over 20 years old in Jiangning District , Shanghai , China . METHODS This was a cross-sectional study . From September 2008 to January 2009 , 6 small districts including 21,102 people of Jiangning District were r and omly selected as survey venues by Department of Ophthalmology in First People 's Hospital affiliated to Shanghai Jiaotong University . Then , 1266 people as the selected residents were enrolled , which was figured out through the r and om cluster sampling procedure . Every participant completed  dry eye question naire , the  ocular surface disease index ( OSDI ) , and a series of examination including slit-lamp microscope , tear-film break-up time ( BUT ) , Schirmer I test , and fluorescein staining of the cornea ( F1 ) .  The diagnosis of dry eye was referred to the well-accepted domestic diagnostic criteria The SPSS11 . 0 software was used to analyze the data base , t . test , chi2 test , one-way-ANOVA and Logistic regression were used for analysis . RESULTS One thous and and eighty five residents finally took part in this study , and the inclusion ratio was 85.70 % . Three hundred and twenty six individuals , including 101 men and 225 women , were diagnosed as dry eye , and the prevalence rate was 30.05 % . The prevalence of dry eye in the female ( 33.78 % ) was higher than that of the male ( 24.11 % ) ( chi2 = 11.46 , P < 0.01 ) . The prevalence of dry eye in people over 50 years old was higher than that under 50 years ( chi2 = 94.50 , P < 0.01 ) . The figure of Schirmer I test and BUT decreased in 
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To conclude , it was found that DED is prevalent across generations in the Japanese population , and costs related to the disease lead to considerable economic burden