To report initial results using a native 240 frames per second smartphone camera for 2-dimensional videographic analysis of eyelid dynamics during spontaneous blinking.
Spontaneous blinking was prospectively recorded in volunteers using a smartphone camera recording at 240 frames per second in 720p. A standardized recording setup was used in which the smartphone was mounted on a tripod stand at 0.5 m in the Frankfort horizontal plane. Subjects viewed a nature documentary video in primary gaze while their spontaneous blinking was recorded for 3 minutes. Exclusion criteria included known eyelid malposition or ocular surface pathology, including dry eye syndrome, contact lens use, prior eyelid or intraocular surgery, prior periocular trauma, or craniofacial abnormality. Primary outcome measures were spontaneous interblink interval, blink rate in blinks per minute, percentage of incomplete blinks, and blink velocity.
The authors studied 10 subjects, 5 men and 5 women. Average age was 34 (range 19–58). Mean interblink interval was found to be 7.4 seconds (SD: 5.2, range: 1.9–17.6), corresponding to a mean blink rate of 13 blinks per minute (SD: 7.8, range: 3.4–32.0). Mean percentage of incomplete blinks was 49.8% (SD: 33.3, range: 0–100). Mean blink closure velocity was 93 mm/seconds (SD: 31, range: 40–160). These numbers are consistent with previously published results of spontaneous eyelid blink parameters.
This study demonstrates that 240 frames per second videography native to modern smartphone cameras captures anatomic detail and blink dynamics with sufficient resolution and clarity to provide objective clinical information about spontaneous eyelid blink rate, dynamics, and function.