Computerized biofeedback to characterize Pupil Cycle Time (PCT) in neuropathies and retinopathies

Abstract

Pupillary responses to light offer a convenient and objective way to quickly assess the functional health of the anterior afferent visual pathways. We here present the characteristics of Pupil Cycle Time (PCT) obtained with a computerized biofeedback setting in patients with retinal and optic nerve diseases. The spectral analysis of the sustained pupillary oscillations elicited over 45 seconds of passive fixation of colored displays with different spatial configurations provides relevant information that allow distinguishing patients from healthy participants with good sensitivity and specificity. PCT measures done with this method could complement the current functional examination of chronic ophthalmic diseases whose prevalence worryingly increases worldwide.

Method to quickly map multifocal Pupillary Response Fields (mPRF) using Frequency Tagging

“…Several clinical studies report correlations between pupillary features of the PLR and Retinal Nerve Fiber Layer (RNFL) estimated with Optical Coherence Tomography (Chang et al, 2013; Najar et al, 2018; Gracitelli et al, 2014; Rukmini et al, 2019; Stelandre et al, 2023; Ajasse et al, 2022). In these studies, depending on the protocol and stimuli at stake, different features of pupillary signals from populations of patients with ophthalmic pathologies are measured and compared to structural characteristics of the retina.…”

“…We used mPFT in several clinical studies to evaluate the extent to which it can be used to classify healthy participants from patients (Ajasse et al, 2022; Stelandre et al 2023; Trinquet et al, in preparation). Acceptability, comfort and feasibility were also evaluated with questionnaires comprising questions about duration, glare, fixating difficulty and fatigue induced by the mPFT test.…”

“…In a first study (Ajasse et al, 2022) 3 rare pathologies were tested at the Paris Vision Institute: Retinitis Pigmentosa (N=14), Stargardt disease (N=14) and Leber hereditary optic neuropathy (N=9). Healthy participants (N=14) were also included.…”

“…A second test used chromatic mPTF. The last test assessed the Pupil Cycle Time (PCT) using a computerized setting (See Ajasse et al 2022). We here report the results for the grey mPFT test only.…”

“…We further analyze the correlation of pupillary spectral power with structural data (RNFL). We end with a summary of clinical studies (Ajasse et al, 2022; Stelandre et al, 2023; Trinquet et al, in preparation) performed with mPFT on several diseases (neuropathies and retinopathies) that demonstrate that this method provide excellent classification results, opening the way to be routinely used in clinical settings.…”