***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: Abstract Purpose : To determine the tear osmolarity in patients with tearing secondary to dry eye and other pathologies , and to determine the prevalence of dry eye disease among patients with tearing in an oculoplastics setting . Methods : 108 eyes of 54 patients with a chief complaint of tearing were prospect ively recruited . Subjects were excluded if they used eye drops or contact lenses within 2 hours of assessment , had a history of refractive surgery , an active ocular allergy , or evidence of a systemic disease which affects tear production . A full medical and ocular history was taken with a complete eye exam pertinent to dry eye .  Tear osmolarity was measured using the TearLab device . A clinical diagnosis of dry eye was made based on findings , without reference to tear osmolarity . Results : Among 86 eyes symptomatic for tearing , 32 eyes had dry eye disease ( 37 % ) . Patients with dry eye had a significantly higher median tear osmolarity compared to that in patients with other diagnoses ( 308 mOsm/L vs. 294 mOsm/L , p < 0.0001 ) . At a cut-off of 308 mOsm/L , tear osmolarity result ed in a sensitivity of 50 % and a specificity of 88 % for the diagnosis of dry eye . Conclusions : A significant proportion of patients with tearing in an oculoplastics practice had dry eye disease . The high specificity of tear osmolarity may render it a useful tool to rule in dry eye disease and may assist the oculoplastic surgeon in more accurately determining the cause of tearing PURPOSE To evaluate the use of tear osmolarity in the diagnosis of dry eye disease . DESIGN A prospect i ve , observational case series to determine the clinical usefulness of tear osmolarity and commonly used objective tests to diagnose dry eye disease . METHODS A multicenter , 10-site study consisting of 314 consecutive subjects between 18 and 82 years of age .  Bilateral tear osmolarity , tear film break-up time ( TBUT ) , corneal staining , conjunctival staining , Schirmer test  , and meibomian gl and grading were performed . Diagnostic performance was measured against a composite index of objective measurements that classified subjects as having normal , mild or moderate , or severe dry eye . The main outcome measures were sensitivity , specificity , area under the receiver operating characteristic curve , and intereye variability . RESULTS Of the 6 tests , tear osmolarity was found to have superior diagnostic performance . The most sensitive threshold between normal and mild or moderate subjects was found to be 308 mOsms/L , whereas the most specific was found at 315 mOsms/L. At a cutoff of 312 mOsms/L , tear hyperosmolarity exhibited 73 % sensitivity and 92 % specificity . By contrast , the other common tests exhibited either poor sensitivity ( corneal staining , 54 % ; conjunctival staining , 60 % ; meibomian gl and grading , 61 % ) or poor specificity ( tear film break-up time , 45 % ; Schirmer test , 51 % ) .  Tear osmolarity also had the highest area under the receiver operating characteristic curve ( 0.89 ) . Intereye differences in osmolarity were found to correlate with increasing disease severity ( r(2 ) = 0.32 ) . CONCLUSIONS Tear osmolarity is the best single metric both to diagnose and classify dry eye disease . Intereye variability is a characteristic of dry eye not seen in normal subjects PURPOSE A prospect i ve , multisite clinical study ( 10 sites in the European Union and the United States ) evaluated the clinical utility of commonly used tests and tear osmolarity for assessing dry eye disease severity . METHODS Three hundred fourteen consecutive subjects between the ages of 18 and 82 years were recruited from the general patient population , 299 of which qualified with complete data sets .  Osmolarity testing , Schirmer test without anesthesia , tear film breakup time ( TBUT ) , corneal staining , meibomian dysfunction assessment , and conjunctival staining  were performed bilaterally . A symptom question naire , the Ocular Surface Disease Index ( OSDI ) , was also administered to each patient . Distributions of clinical signs and symptoms against a continuous composite severity index were evaluated . RESULTS Osmolarity was found to have the highest correlation coefficient to disease severity ( r(2 ) = 0.55 ) , followed by conjunctival staining ( r(2 ) = 0.47 ) , corneal staining ( r(2 ) = 0.43 ) , OSDI ( r(2 ) = 0.41 ) , meibomian score ( r(2 ) = 0.37 ) , TBUT ( r(2 ) = 0.30 ) , and Schirmer result ( r(2 ) = 0.17 ) . A comparison of st and ard threshold-based classification with the composite severity index revealed significant overlap between the disease severities of prospect ively defined normal and dry eye groups . Fully 63 % of the subjects were found to be poorly classified by combinations of clinical thresholds . CONCLUSIONS Tear film osmolarity was found to be the single best marker of disease severity across normal , mild/moderate , and severe categories . Other tests were found to be informative in the more severe forms of disease ; thus , clinical judgment remains an important element in the clinical assessment of dry eye severity . The results also indicate that the initiation and progression of dry eye is multifactorial and supports the rationale for redefining severity on the basis of a continuum of clinical signs . ( Clinical Trials.gov number , NCT00848198 . ) Purpose : To evaluate the tear osmolarity and ocular surface changes in patients with polycystic ovary syndrome ( PCOS ) . Material s and Methods : Forty-eight patients with recently diagnosed PCOS and thirty-three control volunteers were enrolled in this prospect i ve , observational study . Ocular surface disease index ( OSDI ) score was calculated . Tear osmolarity was measured using the  TearLab Osmolarity System ( Tearlab , San Diego , CA , USA ) . All subjects also underwent the following ophthalmologic evaluation : Schirmer I test , tear-film breakup time ( TBUT ) , ocular surface flourescein staining , and conjunctival impression cytology .  Results : Mean OSDI score was significantly higher in patients with PCOS than control subjects ( P = 0.001 ) . Tear osmolarity was similar in both groups ( P = 0.404 ) . There were no significant differences between groups in Schirmer I test results , TBUT , and ocular surface flourescein staining scores ( P > 0.05 ) . Compared to control group , a statistically significant squamous metaplasia was observed in temporal bulbar conjunctival impression cytology specimens in PCOS group ( P = 0.032 ) . Conclusions : In patients with recently diagnosed PCOS , tear volume and osmolarity are not affected but , conjunctival morphology may be affected , though on a limited scale UNLABELLED It has been suggested that tear fluid is isotonic with plasma , and plasma osmolality ( P(osm ) ) is an accepted , albeit invasive , hydration marker . Our aim was to determine whether tear fluid osmolarity ( T(osm ) ) assessed using a new , portable , noninvasive , rapid collection and measurement device tracks hydration . PURPOSE This study aim ed to compare changes in T(osm ) and another widely used noninvasive marker , urine specific gravity ( USG ) , with changes in P(osm ) during hypertonic-hypovolemia . METHODS In a r and omized order , 14 healthy volunteers exercised in the heat on one occasion with fluid restriction ( FR ) until 1 % , 2 % , and 3 % body mass loss ( BML ) and with overnight fluid restriction until 08:00 h the following day , and on another occasion with fluid intake ( FI ) . Volunteers were rehydrated between 08:00 and 11:00 h. T(osm ) was assessed using the TearLab osmolarity system . RESULTS P(osm ) and USG increased with progressive dehydration on FR ( P < 0.001 ) . T(osm ) increased significantly on FR from 293 ± 9 to 305 ± 13 mOsm·L(-1 ) at 3 % BML and remained elevated overnight ( 304 ± 14 mOsm·L(-1 ) ; P < 0.001 ) . P(osm ) and T(osm ) decreased during exercise on FI and returned to preexercise values the following morning . Rehydration restored P(osm ) , USG , and T(osm ) to within preexercise values . The mean correlation between T(osm ) and P(osm ) was r = 0.93 and that between USG and P(osm ) was r = 0.72 . CONCLUSIONS T(osm ) increased with dehydration and tracked alterations in P(osm ) with comparable utility to USG . Measuring T(osm ) using the TearLab osmolarity system may offer sports medicine practitioners , clinicians , and research investigators a practical and rapid hydration assessment technique Abstract Aim : To generate data on the variability of tear osmolarity in a control ( normal , non-dry eye ) and symptomatic dry eye population ( Ocular Surface Disease Index : OSDI ≥20 ) . A secondary outcome is the determination of the effect that tear collection technique has on the osmolarity of the sample . Material s and methods : This was a two-phase study that recruited 20 subjects ( n = 10 normal , n = 10 dry eye ) to evaluate the influence of time between measurements ( Phase I ) and 30 subjects ( n = 15 normal , n = 15 dry eye ) to evaluate the influence of collection technique ( Phase II ) . As part of Phase I , serial  tear osmolarity measurements were performed on each eye ; four separated by 15 min followed by four separated by 1 min , at each of three visits . Phase II compared the consecutive measurement of four in vivo tear sample s to four in vitro measurements on tears collected and dispensed from a glass capillary tube . Results : During Phase I , the dry eye group had a significantly higher maximum osmolarity ( 334.2 ± 25.6 mOsm/L ) compared to the normal group ( 304.0 ± 8.4 mOsm/L , p = 0.002 ) . No significant differences were observed whether collection s were performed at 15 or 1 min intervals . During Phase II , the in vivo osmolarity was equivalent to in vitro measurements from glass capillary tube sample s for both the dry eye group ( 323.0 ± 16.7 mOsm/L versus 317.7 ± 24.8 , p = 0.496 ) , and for the normal subjects ( 301.2 ± 7.2 mOsm/L versus 301.9 ± 16.0 mOsm/L , p = 0.884 ) . Conclusion : Symptomatic dry eye subjects exhibited a significantly higher tear osmolarity and variation over time than observed in normal subjects , reflecting the inherent tear film instability of dry eye disease . There was no change in the distribution of tear osmolarity measurements whether tears were collected in rapid succession or given time to equilibrate , and collection method had no impact on tear osmolarity PURPOSE To independently assess the measurement variability of TearLab System in a clinical setting of one visit and to estimate the minimum number of measurements required for reliable readings of tear osmolarity . METHODS Ten consecutive osmolarity measurements were taken from both eyes by the same examiner at one visit for fourteen subjects . The ocular surface disease index symptoms question naire and tear film break up time were also performed . Group average cumulative mean and cumulative coefficient of variation were calculated to assess the TearLab measurement variation . Repeated application of Thompson 's tau method was performed to identify the outliers in tear osmolarity readings for each eye . Results from both eyes were analysed separately . RESULTS Up to two r and omly occurring outlying values in 10 consecutive measurements were found in 19 out of 28 measured eyes . No statistically significant differences between the left and right eye were found for the group mean and group st and ard deviation ( paired t-test , p=0.099 and p=0.068 , respectively ) , however the cumulative coefficient of variation indicated higher measurement group variability on one eye . Estimated cumulative coefficient of variation indicated the minimum of three consecutive acquisitions required for the measurement to be reliable . CONCLUSIONS TearLab Osmolarity System required at least three consecutive measurements to be taken in order to provide clinical ly reliable tear osmolarity readings . Also , taking the maximum osmolarity value for detecting dry eye disease should be viewed with caution since outlying readings of tear osmolarity frequently occur Purpose : Tear film hyperosmolarity is recognized as an important pathogenetic factor in dry eye syndrome , but difficulties in its measurement have limited its utility in the recent past . This prospect i ve , nonr and omized , clinical single-center study investigates the osmolarity in tear sample s of patients with keratoconjunctivitis sicca compared with healthy controls . Methods : One hundred thirty-three patients [ aged 58 years ( 51–64 years ) , 86 women and 47 men ] with moderate to severe keratoconjunctivitis sicca and 95 controls [ aged 52 years ( 48–61 years ) , 55 women and 40 men ] were enrolled in the trial . Tear sample s were collected directly from the inferior lateral tear meniscus . Inclusion criteria were a tear breakup time of less than 5 seconds , a Schirmer test with anest 
    Output:
    
Conclusions : There is a high variability of osmolarity measurements with the TearLab system .
A substantial number of healthy subjects fulfill the DEWS 's definition of DED .