Validating a new device for measuring tear evaporation rates

Athira Rohit, Klaus Ehrmann, Thomas Naduvilath, Mark Willcox, Fiona Stapleton

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Purpose: To calibrate and validate a commercially available dermatology instrument to measure tear evaporation rate of contact lens wearers. 

Methods: A dermatology instrument was modified by attaching a swim goggle cup such that the cup sealed around the eye socket. Results for the unmodified instrument are dependent on probe area and enclosed volume. Calibration curves were established using a model eye, to account for individual variations in chamber volume and exposed area. Fifteen participants were recruited and the study included a contact lens wear and a no contact lens wear stage. Day and diurnal variation of the measurements were assessed by taking the measurement three times a day over 2 days. The coefficient of repeatability of the measurement was calculated and a linear mixed model assessed the influence of humidity, temperature, contact lens wear, day and diurnal variations on tear evaporation rate. The associations between variables were assessed using Pearson correlation coefficient. 

Results: Absolute evaporation rates with and without contact lens wear were calculated based on the new calibration. The measurements were most repeatable during the evening with no lens wear (COR = 49 g m-2 h) and least repeatable during the evening with contact lens wear (COR = 93 g m-2 h). Humidity (p = 0.007), and contact lens wear (p < 0.01), significantly affected the tear evaporation rate. However, temperature (p = 0.54) diurnal variation (p = 0.85) and different days (p = 0.65) had no significant effect after controlling for humidity. 

Conclusion: Tear evaporation rates can be measured using a modified dermatology instrument. Measurements were higher and more variable with lens wear consistent with previous literature. Control of environmental conditions is important as a higher humidity results in a reduced evaporation rate.

Original languageEnglish
Pages (from-to)53-62
Number of pages10
JournalOphthalmic and Physiological Optics
Volume34
Issue number1
DOIs
Publication statusPublished - 1 Jan 2014

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Contact Lenses
Tears
Equipment and Supplies
Humidity
Dermatology
Calibration
Lenses
Eye Protective Devices
Temperature
Orbit
Linear Models

Cite this

Rohit, Athira ; Ehrmann, Klaus ; Naduvilath, Thomas ; Willcox, Mark ; Stapleton, Fiona. / Validating a new device for measuring tear evaporation rates. In: Ophthalmic and Physiological Optics. 2014 ; Vol. 34, No. 1. pp. 53-62.
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abstract = "Purpose: To calibrate and validate a commercially available dermatology instrument to measure tear evaporation rate of contact lens wearers. Methods: A dermatology instrument was modified by attaching a swim goggle cup such that the cup sealed around the eye socket. Results for the unmodified instrument are dependent on probe area and enclosed volume. Calibration curves were established using a model eye, to account for individual variations in chamber volume and exposed area. Fifteen participants were recruited and the study included a contact lens wear and a no contact lens wear stage. Day and diurnal variation of the measurements were assessed by taking the measurement three times a day over 2 days. The coefficient of repeatability of the measurement was calculated and a linear mixed model assessed the influence of humidity, temperature, contact lens wear, day and diurnal variations on tear evaporation rate. The associations between variables were assessed using Pearson correlation coefficient. Results: Absolute evaporation rates with and without contact lens wear were calculated based on the new calibration. The measurements were most repeatable during the evening with no lens wear (COR = 49 g m-2 h) and least repeatable during the evening with contact lens wear (COR = 93 g m-2 h). Humidity (p = 0.007), and contact lens wear (p < 0.01), significantly affected the tear evaporation rate. However, temperature (p = 0.54) diurnal variation (p = 0.85) and different days (p = 0.65) had no significant effect after controlling for humidity. Conclusion: Tear evaporation rates can be measured using a modified dermatology instrument. Measurements were higher and more variable with lens wear consistent with previous literature. Control of environmental conditions is important as a higher humidity results in a reduced evaporation rate.",
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Rohit, A, Ehrmann, K, Naduvilath, T, Willcox, M & Stapleton, F 2014, 'Validating a new device for measuring tear evaporation rates', Ophthalmic and Physiological Optics, vol. 34, no. 1, pp. 53-62. https://doi.org/10.1111/opo.12096

Validating a new device for measuring tear evaporation rates. / Rohit, Athira; Ehrmann, Klaus; Naduvilath, Thomas; Willcox, Mark; Stapleton, Fiona.

In: Ophthalmic and Physiological Optics, Vol. 34, No. 1, 01.01.2014, p. 53-62.

Research output: Contribution to journalArticleResearchpeer-review

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