Tear and meibomian gland function in blepharitis and normals.

PURPOSE: To determine the differential features of tear physiology and meibomian gland function in blepharitics for ascertaining the diagnostic potential of a number of clinical tests. METHODS: Two groups of subjects, 15 with clinically diagnosed blepharitis (11 women and 5 men mol/L; age 60.9 +/- 12.5; range 41-79) and 15 age- and sex-matched controls (11 women and 5 men mol/L; age 60.7 +/- 12.6; range 40-78), were included in the study. Tear physiology was assessed by evaporimetry and interferometry and the meibomian glands by expression and meibography. RESULTS: Tear evaporation rate was significantly higher (P<0.001) in blepharitics (46.3 +/- 22.9 g/m/hr) than that in normals (18.0 +/- 10.7 g/m/hr). The lipid pattern was found to be significantly less stable (P=0.001) in the blepharitic group compared with that in the normal group. By meibography, meibomian gland dropout was scored and found to be significantly greater (P=0.001) in blepharitics in both the upper eyelids (blepharitis 1.0 +/- 0.8; normal 0.1 +/- 0.3) and lower eyelids (blepharitis 2.1 +/- 8.3; normal 1.0 +/- 0.8). The dropout score was the same or greater for the lower lids than for the upper lids, in all cases. A significant difference (P=0.000) in meibomian gland expression was found between blepharitics and normals; meibum was significantly thicker and more opaque in blepharitics in both the upper (blepharitis 2.2 +/- 0.7; normal 1.0 +/- 0.2) and lower (blepharitis 2.6 +/- 0.7; normal 1.3 +/- 0.4) eyelids. CONCLUSIONS: There are significant differences in tear physiology and meibomian gland function in patients with blepharitis when compared with those without. All the tests employed would be useful as single tests in the diagnosis of blepharitis, with meibomian gland dropout of the lower eyelid offering the greatest effectiveness as a single measure.

Effectiveness of artificial tears in the management of evaporative dry eye.

PURPOSE: To compare the efficacies of sodium hyaluronate, hydroxypropyl methylcellulose (HPMC), and a new oil-in-water emulsion (Emustil unidose; SIFI) in the management of lipid-deficient dry eye. METHODS: Seventy-five subjects with dry eye were randomly divided into 3 groups. Each was allocated sodium hyaluronate, HPMC, or emulsion eyedrops to be used four times daily for 90 days. Parameters were measured at baseline, 30 days, and 90 days. A compliance visit was performed at days 7 and 60. RESULTS: Significant reduction (P < 0.05) in evaporation and improvement in symptoms in all groups were found. No statistically significant increase in tear turnover rate (TTR) was found with any solution. A significant difference in tear stability and noninvasive tear break-up time (NITBUT) was found in the emulsion and sodium hyaluronate groups but not in the HPMC group (P > 0.05). There was a significant decrease in osmolarity and corneal staining in the emulsion group (P < 0.001) but not in the sodium hyaluronate or HPMC group (P > 0.05). CONCLUSIONS: A significant reduction in evaporation and improvement in symptoms in all therapy groups were found from baseline to 90 days. However, no significant effect was seen on TTR for any group. The emulsion drops were shown to perform best, improving tear stability, and decreasing osmolarity and corneal staining. These results are consistent with improvements in the lipid layer of the tear film as a result of prolonged use of emulsion drops.

Comparison of human tear film osmolarity measured by electrical impedance and freezing point depression techniques.

PURPOSE: Tear hyperosmolarity is diagnostic of dry eye disease (DED), yet difficulty in measurement has limited its utility; development of new instruments could facilitate its clinical application. This study compares the new OcuSense TearLab osmometer (OcuSense, Inc, San Diego, CA), based on electrical impedance "lab-on-a-chip" nanoliter technology, with the freezing point depression Clifton Osmometer (Clifton Technical Physics, Hartford, NY). METHODS: Thirty-six subjects were recruited: 15 DED (9 women, 6 men age: 41 +/- 16 years) and 21 controls (12 women, 9 men age: 35 +/- 12 years); criteria for DED were noninvasive tear breakup time <10 seconds, Schirmer I test <5 mm, and positive symptoms. Samples were collected from the inferior tear meniscus for testing with both osmometers. RESULTS: Osmolarity values measured with OcuSense TearLab were 308 +/- 6 and 321 +/- 16 mOsm/L for controls and dry eye, respectively, and those measured with Clifton were 310 +/- 7 and 323 +/- 14 mOsm/L for controls and dry eye, respectively; these values were significantly different. Significant correlation was found between OcuSense and Clifton measurements (r = 0.904; P = 0.006). Bland-Altman analysis revealed agreement between techniques; the majority of points fell within the 95% confidence limits, and actual values differed by less than 1%. A cutoff value of >316 mOsm/L, derived from the distribution of osmolarity values, was used to diagnose DED with an effectiveness of 73% sensitivity, 90% specificity, and 85% positive predictive value for the OcuSense and 73% sensitivity, 71% specificity, and 65% positive predictive value for the Clifton in the study samples. CONCLUSIONS: Tear film osmolarity measured with the OcuSense TearLab system correlates well with the Clifton Osmometer. The new instrument has the potential to provide clinicians with a readily available clinically applicable measure, which could become the gold standard in DED.

A clinical alternative to fluorophotometry for measuring tear production in the diagnosis of dry eye.

PURPOSE: To determine the utility of the tear function index (Liverpool modification TFI) in assessing tear turnover rate (TTR), evaluate association of tear clearance rate (TCR) and TFI with measurements of TTR by fluorophotometry, and determine effectivity of these test measures in dry eye (DE) diagnosis. METHODS: Forty-one subjects with DE and 15 control subjects participated. Tests included symptoms, fluorophotometry (by automated scanning fluorophotometry), and TCR and TFI from a prepared Liverpool modification TFI strip. RESULTS: Significant differences between subjects with DE and control subjects were found for all tests. Although wetting length values gave highest sensitivity (SS) and specificity (SP) (71% and 73%, respectively), this resulted from a high degree of selection bias because the Schirmer test was one of the inclusion criteria for patients entering the study. Therefore, the best tear production test was found to be TTR (SS 71% and SP 60%). The TTR test is not readily available in clinical settings; therefore, associations between the TTR test and other tests were determined. Significant correlations were found between TTR and wetting length/TCR/TFI, indicating these latter clinical tests useful as surrogates. The strongest correlations, TTR/TCR at 0.69 (P = 0.000) and TTR/TFI at 0.65 (P = 0.000), indicate TCR/TFI with the Liverpool test can be used as an alternative to TTR by fluorophotometry. The diagnostic effectiveness between these tests was compared, with both TCR and TFI found to have equal effectivity of 78% SS and 40% SP (TCR) and 83% SS and 40% SP (TFI). CONCLUSIONS: TCR measured by the commercially available Liverpool modification TFI strip is an acceptable alternative to TTR by fluorophotometry as a measure of tear production. It is effective as a single test for the discrimination of those with DE from those without the condition.