Diagnostic accuracy of the iCare rebound tonometer compared to the Perkins applanation tonometer in assessing intraocular pressure in rural patients

Background: Vision health is recognized as a critical unmet need in North America. The ocular morbidity associated with glaucoma results from increased intraocular pressure (IOP) and early detection is crucial for the management of glaucoma. Our objective was to find a diagnostically accurate screening tool for intraocular hypertension that can be used in rural communities. We sought to validate the diagnostic accuracy of the iCare rebound tonometer against the gold standard Perkins applanation tonometer (PAT) in measuring IOP. Methods: Patients from two rural communities in Ontario, Canada visiting their optometrists for routine appointments had their IOP measured by a non-contact tonometer (NCT), an iCare rebound tonometer, and a Perkins applanation tonometer (PAT). Values of sensitivity, specificity, and likelihood ratios for a positive and negative result were calculated for the iCare and the NCT. Results: Complete data was collected from 209 patients. Overall, the iCare tonometer had high levels of validity, as compared to the gold standard PAT. The iCare tonometer displayed excellent sensitivity of 98.3% (90-99%, 95% CI) and excellent negative likelihood ratio of 0.024 (0.0088-0.066, 95% CI) which is useful for ruling out intraocular hypertension. Conclusions: The iCare tonometer is a reasonably valid tool for detecting elevated IOP. Its ease of use, simplicity, and accessibility makes it a good screening tool to improve eye health in rural areas.