Abstract
Purpose: :
The purpose of this study was to measure the effect of an oil-in-water emulsion eye drop on aqueous tear film evaporation rates over time in dry eye patients.
Methods: :
A total of 12 patients with aqueous deficient dry eyes with or without meibomian gland dysfunction were enrolled (11 females and 1 male) with a mean age of 47.4±10.5 years old (62-31 years). The protocol, consent form, and data accumulation methods were approved by the University of Texas Southwestern Medical Center Institutional Review Board. A commercially available artificial tear solution (Systane BALANCE; Alcon Inc., Fort Worth, Texas, USA) was tested. Evaporative measurements were performed at baseline and at 30 and 60 minutes following instillation of 40 µl of the eye drop. An Evaporometer (Oxdata, Portland, Oregon, USA) was used at two ranges of relative humidity (RH) 25% to 35% and 35% to 45% to determine aqueous tear evaporation. The data was expressed in µl/cm2/min.
Results: :
An increase in evaporation rate of the tear film was noted for all measurements at RH of 25% to 35% compared to 35% to 45% (p<0.05). The average evaporation rate at baseline using both RH (25% to 35% and 35% to 45%) was 0.092±0.027 and 0.069±0.022, respectively. Following instillation of the study agent the evaporation rates decreased to 0.083±0.016 and 0.062±0.013 (at 25-35% and 35-45% RH, respectively) at 30 minutes; and 0.082±0.030 and 0.058±0.022 at 60 minutes. The observed decrease at 30 and 60 minutes did not reach statistical significance when compared to baseline values.
Conclusions: :
A 10% reduction in RH from 35-45% to 25-35% resulted in an average increase in evaporation rate of 27% in dry eye patients. In addition, following instillation of the oil-in-water emulsion eye drop the rate of evaporation decreased by 11% at 30 minutes, and 14% at 60 minutes compared to baseline. When compared to baseline, a strong tend was noted that did not reach statistical significance.
Keywords: cornea: tears/tear film/dry eye • lipids