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Automated Pupillometry Using a Prototype Binocular Optical Coherence Tomography System
Reena Chopra1, Pádraig J Mulholland2, Axel Petzold3
1National Institute for Health Research Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital National Health Service Foundation Trust and University College London Institute of Ophthalmology, London, United Kingdom.
Purpose:
To determine the test-retest reliability and diagnostic accuracy of a binocular optical coherence tomography (OCT) prototype (Envision Diagnostics, El Segundo, California, USA) for pupillometry.
Design:
Assessment of diagnostic reliability and accuracy.
Methods:
Fifty participants with relative afferent pupillary defects (RAPDs) confirmed using the swinging flashlight method (mean age 49.6 years) and 50 healthy control subjects (mean age 31.3 years) were examined. Participants twice underwent an automated pupillometry examination using a binocular OCT system that presents a stimulus and simultaneously captures OCT images of the iris-pupil plane of both eyes. Participants underwent a single examination on the RAPDx (Konan Medical, Irvine, California, USA), an automated infrared pupillometer. Pupil parameters including maximum and minimum diameter, and anisocoria were measured. The magnitude of RAPD was calculated using the log of the ratio of the constriction amplitude between the eyes. A pathological RAPD was above ±0.5 log units on both devices.
Results:
The intraclass correlation coefficient was >0.90 for OCT-derived maximum pupil diameter, minimum pupil diameter, and anisocoria. The RAPDx had a sensitivity of 82% and a specificity of 94% for detection of RAPD whereas the binocular OCT had a sensitivity of 74% and specificity of 86%. The diagnostic accuracy of the RAPDx and binocular OCT was 88% (95% confidence interval 80%-94%) and 80% (95% confidence interval 71%-87%) respectively.
Conclusions:
Binocular OCT-derived pupil parameters had excellent test-retest reliability. The diagnostic accuracy of RAPD was inferior to the RAPDx and is likely related to factors such as eye movement during OCT capture. As OCT becomes ubiquitous, OCT-derived measurements may provide an efficient method of objectively quantifying the pupil responses.
