Development and Implementation of a Handheld Pupillometer for Detection of Optic Neuropathies

Basics, benefits, and pitfalls of pupillometers assessing visual function

Numerous commercially and non-commercially available pupillometers are nowadays able to assess various biological functions in humans, by evaluating pupils' dynamics in response to specific stimuli. However, the use of pupillometers for ophthalmic afferent evaluations (i.e., photoreceptoral responses) in real-world settings is relatively limited. Recent scientific and technological advances, coupled with artificial intelligence methods have improved the performance of such devices to objectively detect, quantify, and classify functional disturbances of the retina and the optic nerve. This review aims to summarize the scientific principles, indications, outcomes, and current limitations of pupillometry used for evaluation of afferent pathways in ophthalmic clinical settings.

Pupil assessment with a new handheld pupillometer in healthy subjects

OBJECTIVE

To assess the pupil response with a new handheld pupillometer in healthy subjects.

METHODS

Sixty-four eyes of 32 healthy subjects (mean age 21.2 years) were tested. After dark adaptation for 10 min, pupil responses to 1 s red and blue light stimuli at 100 cd/m² were measured in the order from right to left eyes with a 1 min interval. The initial pupil size (D1, mm), minimum pupil size (D2, mm), and constriction rate (CR, %) were obtained. Intra-examiner reproducibility was examined using the coefficient of variation (CV, %) and the Bland-Altman plot. Inter-examiner consistency was examined using the interclass correlation coefficient (ICC) and the agreements with a conventional device, by Pearson's correlation coefficient (r).

RESULTS

The CV of all parameters have high reproducibility in the red (11.0-20.7%) and blue (5.5-12.1%) light stimuli. Bland-Altman plot analysis showed no bias with both light stimuli. "Almost perfect" and "substantial" correlations between the examiners were obtained in the red (ICC = 0.78-0.94) and blue (ICC = 0.71-0.89) light stimuli. "Excellent" and "good" correlations between the devices were obtained, except for the CR parameter in the red (D1: r = 0.90; p < 0.001, D2: 0.72; p < 0.001, and CR: 0.08; p = 0.631, respectively) and blue (D1: r = 0.87; p < 0.001, D2: 0.70; p < 0.001, and CR: 0.19; p = 0.274, respectively) light stimuli.

CONCLUSION

The novel pupillometer is useful for assessing pupil response. However, because of their different constructions, the CR values cannot be compared directly between the devices.