Effect of central and peripheral cone- and rod-specific stimulation on the pupillary light reflex

Helmut Wilhelm,Carina Kelbsch,Barbara Wilhelm,Krunoslav Stingl,Anton Sonntag,Ronja Jung,Tobias Peters,Torsten Strasser

doi:10.1007/s10792-021-02132-1

Helmut Wilhelm, Carina Kelbsch + Show 6 more

Open Access

https://doi.org/10.1007/s10792-021-02132-1

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Journal: International Ophthalmology	Publication Date: Nov 26, 2021
Citations: 2	License type: open-access

Affiliation: STZ eyetrial, University of Tübingen

Abstract

PurposeTo assess the effect of central and peripheral stimulation on the pupillary light reflex. The aim was to detect possible differences between cone- and rod-driven reactions.MethodsRelative maximal pupil constriction amplitude (relMCA) and latency to constriction onset (latency) to cone- and rod-specific stimuli of 30 healthy participants (24 ± 5 years (standard deviation)) were measured using chromatic pupil campimetry. Cone- and rod-specific stimuli had different intensities and wavelengths according to the Standards in Pupillography. Five filled circles with radii of 3°, 5°, 10°, 20° and 40° and four rings with a constant outer radius of 40° and inner radii of 3°, 5°, 10° and 20° were used as stimuli.ResultsFor cone-and rod-specific stimuli, relMCA increased with the stimulus area for both, circles and rings. However, increasing the area of a cone-specific ring by minimizing its inner radius with constant outer radius increased relMCA significantly stronger than the same did for a rod-specific ring. For cones and rods, a circle stimulus with a radius of 40° created a lower relMCA than the summation of the relMCAs to the corresponding ring and circle stimuli which combined create a 40° circle-stimulus. Latency was longer for rods than for cones. It decreased with increasing stimulus area for circle stimuli while it stayed nearly constant with increasing ring stimulus area for cone- and rod-specific stimuli.ConclusionThe effect of central stimulation on relMCA is more dominant for cone-specific stimuli than for rod-specific stimuli while latency dynamics are similar for both conditions.

Highlights

The effect of central stimulation on relative maximal constriction amplitude (relMCA) is more dominant for cone-specific stimuli than for rod-specific stimuli while latency dynamics are similar for both conditions
Based on several studies using chromatic pupillography that detected changes of the pupillary light reflex (PLR) to explicitly celladdressing stimuli in patients with retinal diseases [13, 14] and glaucoma [15] the Pupil Research Group at the Centre for Ophthalmology developed a new type of device, the Chromatic Pupil Campimeter (CPC): a combination of cell-specific stimuli and a new pupillographic campimetry device introduced by Stingl et al [1]
Kelbsch et al presented this objective method to measure pupil responses separately for rods and L-cones at different locations in the visual field [2] and found that the mean relative maximal constriction amplitude caused by cone-specific stimuli was larger in the centre of the retina and decreased in a hill-shaped form towards the periphery

Summary

Introduction

The use of specific wavelengths, stimulus durations and adaptation states at different locations of the visual field allows responses from rods, cones and intrinsically photosensitive retinal ganglion cells to be studied by pupil campimetry [12]. Based on several studies using chromatic pupillography that detected changes of the pupillary light reflex (PLR) to explicitly celladdressing stimuli in patients with retinal diseases [13, 14] and glaucoma [15] the Pupil Research Group at the Centre for Ophthalmology developed a new type of device, the Chromatic Pupil Campimeter (CPC): a combination of cell-specific stimuli and a new pupillographic campimetry device introduced by Stingl et al [1].

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Conclusion