Fourier Descriptors for Characterizing Waveforms of the Pupil Light Response to Chromatic Stimuli

Wioletta Nowak, Minoru Nakayama, Hitoshi Ishikawa, and Ken Asakawa


Pupil Light Reflex, Waveform morphology, Fourier descriptor, Multidimensional Scaling


The waveform of the Pupil Light Response (PLR) to chromatic stimuli is a key point in non-invasive assessment of the activity of the melanopsin-associated photo receptive system, which is considered as the basis for preparing new diagnostic procedures in ophthalmology. The article shows a procedure for a quantitative description of the PLR waveform for both eyes across stimuli conditions using Fourier descriptors, and another procedure for emphasizing normal and abnormal pupil responses using Multi Dimensional Scaling. To determine the efficiency of this procedure as a clinical diagnostic, a set of PLR data for healthy subjects and patients with Age-Related Macular Degeneration (ARMD) were analyzed. The PLR data were obtained during a classical experiment used to measure melanopsin-associated photo receptive system activity. The results confirmed the diagnostic utility of the proposed procedures for discriminating between normal and abnormal PLR responses.

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