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  • Smartphone Tonometer Effective in Measuring IOP

    By Arthur Stone
    Selected By: Prem S. Subramanian, MD, PhD
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    Journal Highlights

    British Journal of Ophthalmology
    Published online Dec. 23, 2019

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    Wu et al. evaluated the accuracy of a novel smartphone tonometer. They found that the intraocular pressure (IOP) measurements taken with their prototype were roughly equivalent to those obtained via other tonometers used in clinical practice, with the best correlation seen using Goldmann ap­planation tonometry (GAT).

    The tonometer used in this study clamps onto an iPhone 6 that aligns with the camera and flash. It uses fixed force applanation in conjunction with a machine-learning computer algorithm to calculate IOP. For this proof of con­cept study, the researchers enrolled 81 patients (162 eyes) at a university glau­coma clinic. Topical fluorescein/benox­inate (Fluress) was applied to both eyes of each patient, and IOP was measured by trained ophthalmic technicians, first using GAT and then the smartphone device. A subset of 38 patients also were evaluated with other tonometers.

    Of the 162 smartphone recordings obtained from the 162 eyes, the ma­chine learning algorithm was successful in processing 92 (56.8%). Of these, 90 (97.8%) were within ±5 mm Hg of GAT, and 58 (63%) were within ±2 mm Hg of GAT. The mean difference for IOP measurements of the smartphone tonometer versus the other tonometers was +0.24 mm Hg for GAT, –1.30 for Tono-Pen, –1.39 mm Hg for iCare, and –3.71 mm Hg for pneumotonometry.

    The authors noted that a smart­phone-based tonometer such as theirs complements other smartphone attach­ments and applications to facilitate a portable ophthalmological examina­tion, which may improve access to eye care in resource-poor regions.

    The original article can be found here.