Real-Time and Non-Invasive Monitoring of IOP in Glaucoma Patients
Biomedical Engineering
Brianna Botello, Anthony De Luz, Saee Sarang Pangarkar, Aditi Rao
Abstract
Affecting approximately 3 million people in the United States, glaucoma is the leading cause of blindness that manifests due to elevated intraocular pressure (IOP) damaging the optic nerve. Early detection of glaucomatous ocular environments allows for improved prognosis of the disease in an effort to reduce the rate at which symptoms become prevalent. Since glaucoma is a chronic disease, there is a need for real-time, non-invasive IOP monitoring to provide physicians data of IOP fluctuations over time to make decisions with regards to further treatment interventions. Current IOP monitoring devices like the Goldmann Applanation Tonometer and the iCare tonometer are based on principles wherein the magnitude of the corneal stiffness translates to IOP. However, the mechanism employed is not only contact-based and causes discomfort to patients but also makes acquiring frequent measurement inaccessible. Furthermore, nocturnal IOP monitoring is necessary for physicians to gauge the extent of fluctuations which are elevated further by the supine position, however there are currently no FDA-approved devices focused on this need despite its significance.
Eye-D.E.A Labs has developed an ultrasound-based system that determines IOP by measuring stiffness using the rebound of ultrasound waves imparted on the corneal surface. The device is intended for recording IOP measurements intermittently while also timely delivering the recorded information to the physician for review. Technical modeling was conducted using Python for acoustic force generation. Various concentrations of gelatin phantoms were fabricated and IOP values were measured using a clinical tonometer (Reichert Tonopen). The phantoms were subsequently used for validation of the final prototype. Safety of the ultrasound system was verified through measurement of the generated acoustic force and compared to FDA standards regarding ophthalmic ultrasound. The final prototype established a proof-of-concept for an ultrasound-based system capable of detecting corneal stiffness changes through small-scale changes in received echoes.