Intraocular Pressure Determining System Based on Rebound Tonometry

Glaucoma is a common neuropathy that causes irreversible blindness. The main categories of glaucoma are open-angle and closed-angle. Open-angle glaucoma is the most common type and is caused by increased flow resistance through Schlemm's canal. Most cases of open-angle glaucoma are discovered during routine eye exams due to their mainly asymptomatic nature. Intraocular pressure (IOP) is one of the most critical risk factors in diagnosing glaucoma. Tonometry is the procedure of measuring intraocular pressure. Currently, one of the most popular forms of tonometry is rebound tonometry. This paper aims to reproduce the technology behind the rebound tonometer by developing a system that measures the deceleration of a standardized magnetic probe. The system includes a magnetized probe, an electromagnetic propulsion mechanism, and an amplification circuit, with signal processing conducted in real time using a microcontroller and MATLAB. Experimental results demonstrated the system's ability to capture probe deceleration and correlate it with IOP in a simulated medium. The system's performance was evaluated by altering the probe's speed, and the results indicated an apparent variation in induced current relative to probe velocity. However, further optimization is needed to minimize external magnetic interference and increase sampling frequency for improved accuracy. The study lays the groundwork for developing portable and cost-effective rebound tonometers that can provide rapid, non-invasive measurements of IOP.