Pupillary responses driven by ipRGCs and classical photoreceptors are impaired in glaucoma.
OBJECTIVE
The aim was to investigate the involvement of intrinsically photosensitive retinal ganglion cells (ipRGCs) in patients with manifest glaucoma and ocular hypertension (OH) using specific parameters of the pupil light reflex to chromatic stimuli.


METHODS
Twenty-five patients with manifest glaucoma, 16 patients with OH and 16 healthy control subjects were stimulated with 28 lx red (605 nm) or blue (420 nm) light with a duration of either 1 s or 4 s. The consensual pupil light reaction was recorded by means of infrared pupillometry. The maximal relative amplitude (MRA), the post-illumination pupil response PIPRblue-red, and the slope of the response during exposure to the 4 s red stimulus (SORRS) were calculated and compared using ANOVA and Tukey-Kramer post-hoc tests. Correlations between pupil parameters and visual field defects were analyzed using Pearson correlation coefficient r.


RESULTS
PIPRblue-red was reduced in glaucoma patients compared to normals (p < 0.001) and OH (p < 0.01). There was no significant difference between OH and normals. Glaucoma patients showed additionally reduced MRA for red and blue light (p < 0.05) and a pupillary escape during exposure to red light (increased SORRS, p < 0.0005). This pupillary escape could also be seen in single subjects with OH. Significant correlations between pupil parameters and visual field defects were detected.


CONCLUSIONS
The reduced PIPRblue-red indicates a characteristic impairment of the melanopsin-driven pathway of ipRGCs in glaucoma patients, whereas the reduced MRA and increased SORRS suggest a disturbed synaptic function and altered interaction between outer photoreceptors, RGCs, and ipRGCs.
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany. carina.kelbsch@med.uni-tuebingen.de.
Carina
C
Kelbsch
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany.|Department of Orthoptics and Visual Sciences, Faculty of Medical Technology, Niigata University of Health and Welfare, Niigata, Japan.
Fumiatsu
F
Maeda
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany.|Institute for Ophthalmic Research, University of Tuebingen, Tuebingen, Germany.
Torsten
T
Strasser
Department of Clinical Epidemiology and Applied Biometry, University of Tuebingen, Tuebingen, Germany.
Gunnar
G
Blumenstock
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany.
Barbara
B
Wilhelm
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany.
Helmut
H
Wilhelm
Pupil Research Group at the Centre for Ophthalmology, University of Tuebingen, Schleichstraße 12, 72076, Tuebingen, Germany.
Tobias
T
Peters
D000328:Adult; D005260:Female; D005901:Glaucoma / Q000378:metabolism* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D012025:Reflex, Pupillary / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D017299:Rod Opsins / Q000378:metabolism; D014794:Visual Fields; D000099210:Melanopsin
D017299:Rod Opsins; D000099210:Melanopsin
Colour pupillography; Glaucoma; Ocular hypertension; Pupil light reflex; ipRGC