Objective optical assessment of tear-film quality dynamics in patients with meibomian gland dysfunction and aqueous-deficient dry eye optical quality changes in different dry eye subtypes

ABSTRACT

Purpose: To evaluate the optical quality and tear-film dynamics in patients with aqueous-deficient or evaporative subtype of dry eye disease (DED). Methods: Twenty-five aqueous-deficient dry eye (ADDE) patients, 25 DED patients with meibomian gland dysfunction (MGD), and 25 healthy subjects were included in this study. Vision-related health-targeted quality of life was evaluated using the Ocular Surface Disease Index (OSDI) questionnaire. Dynamic recording with a double-pass system (Optical Quality Analysis System [OQAS]) was performed in right eyes. Scattered light was measured as the objective scatter index (OSI) at 0.5-second intervals over 20 seconds without blinking. Then, we recorded OSI every 0.5 seconds within a 20-second period with the subjects asked to blink freely. Several parameters were established to evaluate the dynamic alterations of optical quality and the effects of blinks OSI, OSI standard deviation (SD), ?OSI, ?OSI/time, blinking change (BC), and blinking frequency (BF). Additional clinical examination included tear film break-up time (BUT), Schirmer I test (SIT), fluorescein staining grade (FL), meibomian gland quality, meibomian gland expressibility, and meibomian gland drop-out. Results: The OSI, SD, ?OSI, ?OSI/time, BC, and BF were significantly higher in DED patients than controls (P < 0.01, respectively). The OSI, SD, ?OSI, ?OSI/time, BC, and BF were significantly higher in patients with MGD than patients with ADDE (P < 0.01). In the MGD group, BUT, FL staining score, lid abnormality, meibomian gland expressibility, and meibomian gland drop-out were correlated with ? OSI and ? OSI/time. Conclusion: Dry eye patients with MGD had significant alterations of optical quality compared with ADDE patients. The double-pass system has potential to be a useful quantitative method to evaluate the optical quality and tear-film dynamics in patients with dry eye.