Glaucoma is a progressive eye condition that damages the optic nerve leading to vision loss or blindness. The primary treatable risk factor for glaucoma patients is increased intraocular pressure (IOP). IOP is measured regularly in eye exams to screen, diagnose and assess treatment responses for glaucoma. Current devices used by ophthalmologists to measure IOP, such as the Goldman applanation tonometer, acquire only a single IOP measurement during the eye exam. A single IOP measurement is an inaccurate representation because IOP varies throughout the day with the circadian rhythm and in response to physical activity, recumbency, and the cardiac cycle. While devices for continuous IOP monitoring have been developed, such as the Sensimed Triggerfish, they are also faced with limitations. For instance, the Triggerfish does not directly measure IOP, but instead measures fluctuations in ocular volume, which is not as accurate when diagnosing glaucoma. These limitations highlight the need for a versatile device that provide an accurate and continuous measurement of IOP to diagnose glaucoma.
Researchers in the Department of Ophthalmology and Biomedical Engineering at UNC – Chapel Hill and Biomedical Engineering at the University of Miami are developing a novel contact lens to continuously measure IOP. The contact lens will contain an array of cantilevers to measure IOP, permit oxygen transmissibility for use over 24 hours, and contain features to ensure proper positioning. When the cantilever array is in contact with the corneal surface, a change in IOP is detected through the deflection of a cantilever. This provides an output signal based on the change in IOP, through a receiving circuit coupled to a cantilever and subsequent wireless transmission to an external data acquisition unit. The IOP data recorded over a 24-hour period in the external unit can then be analyzed to provide a more complete picture of eye health. By accurately measuring IOP over 24 hours, this device would allow for improved diagnosis of glaucoma in patients and enable optimized treatment plans. Feasibility studies are underway with a prototype device to evaluate measurement of IOP in cornea models used for surgical simulations and cadaver cornea tissue. Additionally, initial safety studies are underway using cadaver cornea tissue.
- The cantilever array design provides more accurate measurements of IOP over existing devices.
- 24-hour continuous monitoring of IOP for a complete picture of eye health.
- Minimal burden on user through a wireless design for data transmission.
This device can be used to measure IOP continuously and accurately to improve diagnosis of glaucoma patients. Additionally, the device can also be used to provide accurate measurements of IOP in patients who have undergone corneal or refractive surgery.