Abstract
Purpose :
Eyelid blinking protects the globe and lubricates the ocular surface. There is insufficient information on the coordination of eyelid blinking dynamics between eyes and the effects of positional changes. This observational study examines the dynamics of a normal, spontaneous blink.
Methods :
Six normal, healthy adult subjects without adnexal, facial, neurologic or ocular pathology that may affect blinking were studied. One minute of spontaneous, bilateral blinking activity was recorded at 240 frames per second in upright and supine positions. Eyelid closure velocity and amplitude were calculated in horizontal (x) and vertical (y) axes for each eye using the Tracker® Video Analysis and Modeling Tool program.
Results :
The average age of subjects was 35 years (range 26-48). In the upright position, mean x-axis velocity was 35.3mm/s (SD 13.5) and mean y-axis velocity was 102mm/s (SD 31.3). The mean x-axis amplitude was 2.57mm (SD 0.843) and mean y-axis amplitude was 7.36mm (SD 1.89). When supine, mean x-axis velocity was 33.1mm/s (SD 12.8) and mean y-axis velocity was 93.7mm/s (SD 34.1). The mean x-axis amplitude was 2.31mm (SD 0.790) and mean y-axis amplitude was 6.34mm (SD 1.85). Individually, the y-axis amplitudes in each eye were found to be significantly reduced when supine compared to upright (OD 1.06mm, p<0.001; OS 0.988mm, p<0.001). The y-axis velocity was also significantly reduced by 9.31mm/s (p=0.03) in OD when supine compared to upright. Asymmetry was noted as OS closed further with greater y-axis amplitude both upright (OD 6.85mm vs. OS 7.87mm; p=0.001) and supine (OD 5.79mm vs. OS 6.88mm; p<0.001). No delay in closure initiation between the eyes was detectable at 4.17ms per video frame.
Conclusions :
This study of normal, spontaneous eyelid blinking demonstrates findings consistent with previous studies of upright eyelid blinking velocity. Differences observed in the supine position may be related to changes in the direction of gravitational pull on the eyelid, and to our knowledge have not been described before. The OS/OD differences may be attributed to dominance, favoring more complete closure of OS, controlled by the right cerebral hemisphere which controls emotional expression. These findings will provide a baseline for future studies to characterize changes in eyelid blinking dynamics with age and in patients with flaccid facial paralysis.
This is a 2020 ARVO Annual Meeting abstract.