Intraocular pressure (IOP) is the pressure exerted by the eye contents on the eyeball wall and is used to maintain the shape of the eyeball. It may cause glaucoma when the dynamic balance of the generation and excretion of aqueous humor in the eyeball is broken. The Goldmann applanation tonometer (GAT) based on the Imbert-Fick principle is considered to be the reference standard for glaucoma diagnosis in clinics. OCT is widely used for eye screening by imaging structural changes caused by various eye diseases. In this paper, we have developed an OCT-assisted transparent flexible force sensing system (O-FPSS) for IOP measurements. In general, the hybrid O-FPSS consists of a droplet-based flexible transparent force sensor placed over an optical coherence tomography imaging lens, in which the IOP measured once the apex of the cornea is flatted by the sensor. According to the Imbert-Fick law, when cornea is flattened, the pressure applied by the sensor equals to the IOP. Specially, the droplet-based capacitive flexible force sensor is consisted by two flexible conductive membranes, and an ionic is sandwiched in between, in which the force applied on the cornea can be monitored by the output. The sensing membrane deforms uniformly upon contacting the cornea, leading to the expansion of the droplet and an increase of the overall capacitance. On the other hand, to get the flatten area between the sensor and the cornea, a swept-source OCT (SS-OCT) is used to record the interfacial with a resolution of 5μm.

Date Published: 5 November 2018
PDF: 8 pages
Proc. SPIE 10816, Advanced Optical Imaging Technologies, 108161Q (5 November 2018); doi: 10.1117/12.2502636

Published in SPIE Proceedings Vol. 10816:
Advanced Optical Imaging Technologies
Xiao-Cong Yuan; Kebin Shi; Michael G. Somekh, Editor(s)