Binocular Summation in Postillumination Pupil Response Driven by Melanopsin-Containing Retinal Ganglion Cells

Abstract

PURPOSE.To investigate how melanopsin-mediated intrinsically photosensitive retinal ganglion cell (ipRGC) signals are integrated binocularly using chromatic pupillometry. We hypothesized that if the melanopsin system is summative, there will be a greater postillumination pupillary response (PIPR) under binocular conditions after viewing bright blue light.METHODS. Pupillary responses in 10 visually normal participants were recorded with an eye tracker following full-field stimulation of red (long wavelength) and blue (short wavelength) light of equal intensity (dim: 0.1 cd [candela]/m 2 , bright: 60 cd/m 2 ) and duration (400 ms). Individual monocular (left eye) pupil responses were measured first, followed by binocular responses. Each participant repeated the same protocol on 3 separate days, at similar times of day. PIPR was recorded for bright red and blue conditions only, whereas maximum pupillary constriction (MPC) was measured under both bright and dim conditions during red and blue light stimulation.RESULTS. Bright blue light stimulation induced greater PIPR under binocular than monocular viewing conditions (F (1,9) ¼ 79.52, P < 0.001). Bright red light stimulation induced minimal PIPR and showed no significant difference between viewing conditions post Bonferroni correction (F (1,9) ¼ 5.49, P ¼ 0.04). MPC was greater during binocular than monocular viewing conditions for all light stimuli, but was greatest following blue compared to red light stimulation. CONCLUSIONS.A larger PIPR was induced using a binocular than a monocular full-field stimulus of equal intensity and duration, demonstrating that melanopsin-mediated ipRGC signals are summated binocularly. This study expands our current understanding of the melanopsin system and may be used as an additional marker to stratify diseases according to their etiologies.

Symptoms of Dementia in Elderly Persons Using Waveform Features of Pupil Light Reflex

“…The observation procedures and the characteristics extracted from PLRs have been discussed regularly. Some characteristics of PLR waveforms are extracted and compared with light wavelengths of colours such as blue or red [9,42] as suggested in previous works [21,20,18]. Though some PLR-based diagnostic prediction procedure using features of the waveforms are proposed [32,31], key features of PLRs and the appropriate procedures have not yet been extracted.…”

“…Most of these procedures are based on the performance of signal transfer from retinal ganglion cells to the pretectal area via the optic chiasm, while the Edinger-Westphal (E-W) Nucleus also plays a major role in PLR [28,42,22]. Some impairment of the transfer path and the E-W Nucleus, such as neuronal loss, may influence AD patients [37,8].…”

“…In regards to the diagnostic issues, observation of these conditions should be focused on using the responses of each eye, even when the reactions of both eyes are measured synchronously. In most studies, the difference between the eyes is not considered since both pupils and eyes are thought of as changing synchronously, such as during consensual light response [42]. Also, similar processing can even be employed during diagnostic procedures which use PLR responses.…”

Noncontact brain–computer interface based on steady-state pupil light reflex using independent bilateral eyes stimulation

“…To account for individual variability in pupil size, the pupil data were normalized to a 5 s baseline period before each stimulus onset (i.e., normalized pupil size = absolute pupil size/baseline pupil size) [11]. In all the participants, no differences in pupil diameters between the left and right eyes were observed.…”

Artificial Intelligence Segmentation Algorithm-Based Optical Coherence Tomography Image in Evaluation of Binocular Retinopathy

“…However, binocular retinopathy is a genetic disease which is difficult to use effective drugs to treat [ 3 , 4 ]. The factors causing retinopathy are relatively complex, and different cases are analyzed according to the specific situation [ 5 , 6 ].…”