iPhone-based Pupillometry: A Novel Approach for Assessing the Pupillary Light Reflex

Area of Science:

• Ophthalmology
• Medical Devices
• Physiology

Background:

• The pupillary light reflex (PLR) is a critical diagnostic measure in optometry and medicine.
• Traditional PLR evaluation relies on subjective, qualitative observation.
• There is a need for objective, quantitative, and portable methods for PLR assessment.

Purpose of the Study:

• To introduce a novel iPhone-based application for real-time pupillary light reflex (PLR) recording.
• To compare the technical performance of this mobile application against a standard laboratory infrared (IR) camera system.

Main Methods:

• Pupil sizes were measured in 15 visually normal subjects using both an IR camera and the iPhone-based Sensitometer test.
• The Sensitometer test utilizes the iPhone flash to elicit constriction and its camera for real-time pupil size recording.
• Key metrics included dark-adapted steady-state pupil size, minimum pupil size post-flash, and redilation phase, analyzed using Bland-Altman methods.

Main Results:

• Strong statistically significant correlations were observed between the IR camera and Sensitometer test for both PLR (r = 0.91) and redilation size (r = 0.65).
• Bland-Altman analysis revealed excellent agreement, with mean differences of 6% for PLR and 1% for redilation size.
• The limits of agreement were 14% for PLR and 5% for redilation size, indicating high reliability.

Conclusions:

• The Sensitometer test demonstrates excellent agreement with established IR camera systems for measuring the pupillary light reflex.
• This iPhone-based pupillometer offers a simple, portable, and cost-effective solution for quantitative pupillary measurements.
• The technology presents a highly promising advancement for clinical practice in optometry and beyond.