"A mathematical study of the influence of a blink"

Abstract: The blink plays an important role in the health and function of our eyes.  For example, the blink facilitates the re-establishment of an optically-smooth surface necessary for refraction, and it removes any irritants, such as dust, from the ocular surface.  Furthermore, for contact lens wearers, it is the forceful blink that inserts the contact lens onto the front of your eye, and it is the blink that moves the contact lens around delivering fresh tear fluid and oxygen to the ocular surface covered by the lens.   In this talk, I will explain two different research efforts underway to quantify the influence of a blink in (i) tear film formation and (ii) contact lens re-centering. 

During a blink, tear fluid supplied from the lacrimal gland is distributed from the upper meniscus region onto the ocular surface to form a stable tear film. Because the current state-of-the-art instrumentation does not yet have the capability to estimate the tear film thickness over the entire front of the eye, especially near the lids during the upstroke and downstroke, it is not fully understood how the tear supply impacts the tear film formation, and thus subsequent tear film thinning during the interblink.  I will explain the insight we have gained by developing and analyzing a mathematical model of the tear film thickness evolution on a realistic moving eye-shaped domain. 

An important mechanical feature of a contact lens is its ability to re-center on the front of the eye when displaced by the lids.  In equilibrium, the contact lens pushes and pulls on the ocular surface generating a suction pressure in the tear film between the surface of the eye and the back side of the lens.  The lid can displace the lens from its equilibrium position.  We have proposed a mechanism for the re-centering of the contact lens based on generated suction pressure gradients in the tear film.  I will explain the mathematical model we developed to verify our hypothesis.  

Host: AWM