Abstract
Abstract: :
Purpose: Dry eye symptoms are often associated with soft contact lens (SCL) wear and are possibly affected by the wind in outdoor or the office. This study aimed to explore the effect of wind velocity on tear film on SCL. Methods: Enrolled subjects were all daily SCL wearers, aged 21.5±2.0 (mean±SD, n=11). The wind was produced artificially with an electric fan and was applied against subject’s right eye, which wore a high water content of SCL (72.0% in water content). Velocities of artificial wind VAW) were set at 0.0m/s (Test 1), 0.5m/s (Test 2), 1.0m/s (Test 3) and 5.5m/s (Test 4) under standardized condition (air temperature: 25°C, relative humidity: 40%). Tear volumes were evaluated by measuring tear meniscus radius (TMR) before and during SCL wearing with a video meniscometer (Yokoi, Cornea, 2000). Tear interference patterns on the CL (TIPCL) were assessed using a video interferometer (Yokoi, AJO, 1996) and graded into one of 5 original grades (Increased grades for thinner film). Non–invasive tear film breakup time (NIBUT) before and during the wearing of SCL were assessed using a video interferometer. Eye dryness before and during the wearing of SCL were scored by asking each subject. Results: No significant difference was recorded in TMR before SCL wearing at each wind velocities. However, TMR (mm) during SCL wear decreased with every blink in Test 3 and 4 [In Test 3: 0.26±0.06 (mean±SD), 0.21±0.06, and 0.20±0.05 respectively after the initial, second, and third blink; In Test 4: 0.25±0.06, 0.19±0.03, 0.18±0.05, respectively]. Grades of TIPCL significantly increased as the VAW increased (p<0.05). NIBUTs before SCL wearing were not significantly changed but NIBUTs during the wearing of SCL were significantly decreased as the VAW increased (Test 1: 4.7±0.8, Test 2: 4.5±1.6, Test 3: 1.9±1.0, Test 4: 0.6±0.7; p<0.05 between Test 1 and 3, and Test 1 and 4). Scores of dryness before and during the wearing of SCL were significantly increased as the VAW increased (Before the SCL wearing: Test 1: 0.4±0.7, Test 2: 0.5±0.7, Test 3: 1.3±0.9, Test 4: 1.5±0.8; during SCL wearing, Test 1: 0.5±0.8, Test 2: 0.6±0.8, Test 3: 2.1±0.7, Test 4: 2.5±0.7; p<0.05). Conclusions: In eyes with SCL exposed to artificial wind, tear film on SCL became thinner and unstable, with increase dryness, but they are not compensated due to the decrease in the tear volume by the accelerated evaporation.
Keywords: contact lens • cornea: tears/tear film/dry eye • cornea: clinical science