Abstract
Purpose: :
Dry eye symptoms are often associated with soft contact lens (SCL) wear and are possibly affected by abnormality of tear film on the SCL. This study aimed to explore the relationship between dryness and tear dynamics, as well as dryness and tear volume during SCL wear. The relationship between tear volume and tear dynamics on the SCL was also assessed.
Methods: :
Fifty–seven daily SCL wearers [aged 32.3±6.4 (mean ± SD)] were enrolled in this study. Different types of brand–new hydrogel SCL, in the same prescription normally worn by each patient, were used. Dryness [visual analog scale rating of 0 mm = no dryness to 100 mm = extreme dryness] was evaluated. In regards to tear dynamics on the SCL, the tear interference pattern (TIPCL) and non–invasive tear film breakup time (NIBUT) were both assessed using a video interferometer (Yokoi, AJO, 1996). The TIPCL was graded from 1 to 5, with 5 representing the thinnest film (Maruyama, IOVS, 2004). Tear volumes were evaluated by measuring tear meniscus radius (R) at the lower lids during SCL wear with a video meniscometer (Yokoi, Cornea, 2000).
Results: :
There were significant correlations of dryness with the grade of TIPCL [r=0.355, p=0008: Spearman’s rank correlation coefficient (SRCC)], and NIBUT on the SCL (r=–0.321, p=0002: SRCC), and R [r=–0.465, p<0.0001: Pearson’s correlation coefficient (PCC)]. R also had a correlation with the grade of TIPCL (r=–0.512, p<0.0001: SRCC) and NIBUT on the SCL (r=0.602, p<0.0001: SRCC).
Conclusions: :
There were relationships between dryness and tear dynamics on the SCL and tear volume. Namely, decreased tear volume produces a thinner and unstable tear film on the SCL, leading to increased dryness.
Keywords: contact lens • cornea: tears/tear film/dry eye • clinical laboratory testing