Tear Physiology of Aqueous Deficiency and Evaporative Dry Eye

Khanal, Santosh; Tomlinson, Alan; Diaper, Charles

doi:10.1097/opx.0b013e3181bc63cc

Cited by 49 publications

(49 citation statements)

References 26 publications

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“…Both methods require expert technical support and time and are open to potential errors because of evaporation of test samples. 3,13,26,27 The feasibility of measuring the tear film osmolarity as an objective test in the diagnosis of dry eye is greatly enhanced by the availability of a commercial device using electrical impedance. The TearLab is a volume-independent tear osmometer based on electrical impedance and ''lab-on-achip'' technology.…”

Section: Discussionmentioning

confidence: 99%

Tear Film Osmolarity Measurements in Dry Eye Disease Using Electrical Impedance Technology

Jacobi

Kruse

et al. 2011

Cornea

134

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Section: Discussionmentioning

confidence: 99%

Tear Film Osmolarity Measurements in Dry Eye Disease Using Electrical Impedance Technology

Jacobi

Kruse

et al. 2011

Cornea

134

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“…, 22 , 23 This increase is due to poor tear film quality, especially of the lipid component of the tears. This inability of the lipid layer to effectively prevent tear fluid loss from the ocular surface is exacerbated by adverse environmental conditions such as low humidity.…”

Section: Discussionmentioning

confidence: 99%

Effectiveness of Dry Eye Therapy Under Conditions of Environmental Stress

Tomlinson

Madden

Simmons

2013

Current Eye Research

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Purpose: Dry eye is often characterized by increased tear evaporation due to poor tear film quality, especially of the lipid component of the tear film. Using an environmental chamber to induce environmental stress, this study compared the effect of three lubricant eye drops on various aspects of tear physiology in a crossover design (evaporation was the principal outcome measure). Methods: Three eye drop formulas were tested: 0.5% carmellose sodium (Drop C), 0.5% carmellose sodium with added lipid (Drop C-L) and 1.0% glycerine with added lipid (Drop G-L). Nineteen control and 18 dry eye subjects used each product for 2 weeks, three times per day, in a random order, with a minimum 1-week washout between treatment periods. Tear evaporation, break up time, osmolarity, tear structure (by interferometry) and patient symptoms were assessed with the subjects adapted for 10 min in an environmental chamber controlled at 20% relative humidity and 22 °C. The treatment effects were analyzed using general linear model repeated measures analyses of variance. Results: In dry eye subjects, evaporation, break up time, osmolarity and symptoms improved for all formulas (p < 0.05). Normal subjects showed some improvements: evaporation with C-L, osmolarity with C and symptoms with C-L and G-L. Change in evaporation was greater for both C-L and G-L versus C (p < 0.05), and there was a trend for C-L to reduce evaporation more than G-L (p < 0.11). There were no significant treatment effects on tear film structure. Conclusion: Overall, the eye drop formula containing both carmellose sodium and lipid (C-L) produced a greater treatment effect on tear evaporation than the other formulations containing only one of these ingredients. This study also demonstrates the utility of a controlled environmental chamber in showing the difference in performance between dry eye treatments.

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“…This may explain the lower osmolarities and the absence of differences between normal and dry eye groups reported by others. 9,14–16,35 In addition, an awareness of the positioning of the test card tip on the ocular surface may unintentionally induce a hypersecretory reflex in some subjects, 14,37 especially in subjects with low tear volumes who require longer sampling times to collect an appropriate quantity of tears. Reflex tearing during the test may cause some sampling-induced variations in tear osmolarity.…”

Section: Discussionmentioning

confidence: 99%

Daytime Variations of Tear Osmolarity and Tear Meniscus Volume

Zhu

et al. 2012

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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Objectives To determine the pattern of variations in tear osmolarity and tear meniscus volume in dry eye patients and in healthy control subjects over an 8-hour daytime period. Methods Ten normal subjects (5 males and 5 females with a mean age of 27 ± 7 yrs) and 10 dry eye patients (4 males and 6 females with a mean age of 36 ± 12 yrs) who had been diagnosed on the basis of having an ocular surface discomfort index (OSDI) >12 and a tear breakup time of < 10 seconds or Schirmer’s test score of < 5 mm were included. The tear meniscus volumes of the participants were measured using ultra-high resolution optical coherence tomography (OCT), and tear osmolarity was measured using the TearLab Osmolarity System. Both measurements protocols were conducted on the right eye of each participant every two hours beginning at 8:30AM and ending at 4:30PM. OCT imaging was performed first and was followed by osmolarity testing. Results The mean tear osmolarity of the dry eye patients was 304.0 ± 10.8 mOsm/L, and the mean tear osmolarity of the normal subjects was 298.0 ±14.2 mOsm/L (P > 0.05). Over the course of 8 hours, the average measured osmolarities of the dry eye group varied by approximately 21.9 ± 13.5 mOsm/L (range, 6–43 mOsm/L), and the average measured tear osmolarities of the normal group varied by approximately 21.0 ± 9.2 mOsm/L (range, 8–35 mOsm/L). At 2:30 PM, the average volume of the tear menisci in the dry eye group was significantly lower than that of the subjects in the normal group (P < 0.05). No correlations between the tear meniscus volumes and tear osmolarities of either group were observed. Conclusions Variations in the tear osmolarities of individual dry eye patients and healthy normal control subjects were documented over the course of 8 daytime hours. No relationships between tear osmolarities and tear meniscus volumes were observed.

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Tear Physiology of Aqueous Deficiency and Evaporative Dry Eye

Abstract: Tear turnover is significantly lower in ADDE than EDE, but there is considerable overlap of tear evaporation between the two dry eye subtypes. Tear osmolarity and turn over tests can be conducted sequentially to effectively diagnose dry eye and its subtypes.

Cited by 49 publications

References 26 publications

Tear Film Osmolarity Measurements in Dry Eye Disease Using Electrical Impedance Technology

Tear Film Osmolarity Measurements in Dry Eye Disease Using Electrical Impedance Technology

Effectiveness of Dry Eye Therapy Under Conditions of Environmental Stress

Daytime Variations of Tear Osmolarity and Tear Meniscus Volume

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