Development of a method to measure upper eyelid pressure on the cornea

Abstract

Purpose: The cornea is known to be susceptible to forces exerted
by eyelids. There have been previous attempts to quantify eyelid
pressure but the reliability of the results is unclear. The purpose
of this study was to develop a technique using piezoresistive pressure
sensors to measure upper eyelid pressure on the cornea.
Methods: The technique was based on the use of thin (0.18 mm)
tactile piezoresistive pressure sensors, which generate a signal
related to the applied pressure. A range of factors that influence the response of this pressure sensor were investigated along with
the optimal method of placing the sensor in the eye.
Results: Curvature of the pressure sensor was found to impart
force, so the sensor needed to remain flat during measurements.
A large rigid contact lens was designed to have a flat region to
which the sensor was attached. To stabilise the contact lens during
measurement, an apparatus was designed to hold and position
the sensor and contact lens combination on the eye. A calibration
system was designed to apply even pressure to the sensor when
attached to the contact lens, so the raw digital output could be
converted to actual pressure units.
Conclusions: Several novel procedures were developed to use
tactile sensors to measure eyelid pressure. The quantification of
eyelid pressure has a number of applications including eyelid
reconstructive surgery and the design of soft and rigid contact
lenses.