Assessment of Tear Film Optical Quality Dynamics

To investigate tear film optical quality dynamics by analyzing the postblink temporal changes of objective scatter index (OSI).

A total of 109 myopic subjects without symptoms of dry eye and 32 myopic subjects diagnosed with dry eye disease were recruited in this cross-sectional study. The right eye for each subject was analyzed. Serial measurements of OSI were performed for 20 seconds in the interval of 0.5 second using a double-pass instrument, and 10 successive seconds of nonblinking immediately after a blink was selected to analyze the tear film optical quality dynamics. The tear breakup time (TBUT) was also measured. The mean OSI in 10 successive seconds and the correlation coefficient between OSI and time were analyzed.

For subjects without symptoms of dry eye, 109 eyes were divided into two categories based on the correlation coefficient between OSI and time: category A (without positive correlation) and category B (with positive correlation). Categories A and B were further divided into four categories based on the mean OSI for 10 seconds: category A1 (36.7%, lower than 1.00); category A2 (33.0%, equal to or greater than 1.00); category B1 (13.8%, lower than 1.00), and category B2 (16.5%, equal to or greater than 1.00). Dry eye subjects were set as category C for comparison. There was no significant difference in the TBUT among the five categories (A1, A2, B1, B2, C) except between category C and category A1 (P < 0.01) and category C and category A2 (P < 0.05).

Dynamic changes of OSI after blinking showed variations even in clinically asymptomatic subjects, and four categories of tear film were proposed based on the optical quality dynamics. The procedure using serial measurements of OSI as a noninvasive and objective method may have potential applications for detecting preclinical phase of dry eye disease in asymptomatic subjects.