Noninvasive measurement of tear film break-up time in eyes with high-water-content contact lenses

Objective: To evaluate changes in tear dynamics under soft contact lenses (SCLs) by measuring the noninvasive Keratograph break-up time (NIKBUT) in subjects wearing SCLs. Methods: The study included 24 eyes of 12 subjects (10 women and 2 men; age range, 19-38 years) with experience wearing contact lenses and without ocular surface disease except for a refractive error. An infrared video-topographer was used to measure the NIKBUTs with and without high-water-content contact lens. The subjects were asked to grade their subjective feeling of dehydration on a scale of 0 to 3, with 0 indicating no dehydration and 3 indicating maximal dehydration. Results: The eyes were divided into two groups: group A comprising 16 eyes that showed a significant decrease (P < 0.05) in the NIKBUTs with SCLs, and group B comprising eight eyes in which the NIKBUTs remained unchanged. The NIKBUTs without SCLs were significantly longer (P < 0.001) in group A than in group B. The subjective feelings of dehydration decreased significantly (P < 0.001) among subjects with SCLs in group B, whereas the subjective feelings remained unchanged among subjects in group A. Conclusions: The NIKBUTs became relatively shorter with SCLs regardless of the basal NIKBUT of a bare eye. The changes in the NIKBUTs with SCLs could be classified into two groups. These findings offer new insights into the mechanism underlying SCL-induced complications