Abstract
Purpose :
Lateral eye movements are natural and common but the effects of the eye moving on tear film behavior are largely unknown. These lateral eye movements are not considered during eye examinations because subjects are required to look straight ahead. This study is to determine what happens to the tear film during lateral eye movements.
Methods :
15 participants (10 male, 5 female; mean age 26 with two male outliers age 70) had no ocular surface related complaints (OSDI <13) and no fluorescein staining. Tear film dynamics of a sequence of open-eye gaze maneuvers (saccadic abduction-adduction, finger following) were recorded in real time using a TearView camera system. This detects the tear film based on natural infrared emission from the ocular surface. The study was non-interventional, observational and did not involve a control group.
Results :
Lateral eye movements expose new ocular surface not previously covered by the tear film.
The tear film margins react to eye movements by spreading towards the newly uncovered ocular surface areas, thereby recoating them. Additional flow comes from a tear reservoir around the caruncle. No flow occurs from the menisci onto the ocular surface.
Conclusions :
Lateral eye movements rip the tear film away from the lid margins. The sheer forces fluidize the existing tear film allowing it to flow towards the newly exposed ocular surface. In addition, a reserve of tears around the caruncle provides an immediate buffer for filling in this gap in the tear film. It is speculated that this tear reservoir would be diminished in patients with dry eye and so the ocular surface would remain exposed. This complex behavior of the tear film during lateral gaze also needs to be considered in oculoplastic surgery of the canthal regions.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.