A novel contact lens-based intraocular pressure (IOP) monitoring device can capture ocular deformation due to IOP changes, according to research published in Eye.
“Contact lens-based IOP monitoring may allow for a noninvasive continuous IOP monitoring; however, such devices rely on the ability of a soft contact lens to reliably mirror the deformations of the cornea that occur with changes in IOP,” researchers explain.
The experimental study used 12 cadaveric eyes. For each eye, the IOP was increased from 10 to 36 mm Hg. The investigators used video imaging to capture the 3 experimental variations. The deformation of the bare eye served as a control. The team evaluated and compared the deformation of an overlying silicone grided contact lens and an overlying microfluidic IOP-sensing contact lens.
According to the report, the association between the slope of the radius of corneal curvature vs the IOP for both the bare eye and the marker contact lens resulted in a linear relationship with a R2 value of 0.83. The microfluidic contact lens demonstrated an average performance of 0.40 mm indicator movement/mmHg (standard deviation 0.006), the report shows.
When the slope of the marker contact lens deformation was compared with the performance of the microfluidic contact lens, it resulted in a R2 value of 0.78. The strain map of the overlaying grided contact lens revealed most deformation occurring along the outer edge of the lens with increased deformation as IOP increased and with some negative, compressive movement close to the central points.
Compared with the only contact lens-based IOP monitoring device currently on the market, “the contact lens sensor reported here has a simpler fabrication process and a thinner structure, and uses patients’ smartphone rather than a special reader to read and process the sensing information, which could lead to a less expensive, more comfortable and more accessible alternative device for IOP monitoring,” according to the researchers. “Overall, a soft contact lens deformation has a strong linear correlation to the deformation of the curvature of the eye. The edge of the soft contact lens is more deformable than its center, allowing these contact lens-based IOP monitoring devices to effectively capture the deformation of the eye due to the fluctuations of the IOP, and to be a useful tool for frequent and convenient IOP tracking.”
Study limitations include failure to consider biomechanical properties of the tissue itself, failure to assess the influence of central corneal central thickness and radius of corneal curvature, and the experimental set up required a horizontal configuration to enable unrestricted eye deformation, which may affect certain dynamics of eye deformation.
Campigotto A, Campbell RJ, Lai Y. Correlation between corneal and contact lens deformation with changes in intraocular pressure for wearable monitoring systems. Eye. Published online October 27, 2022. doi:10.1038/s41433-022-02285-y