Pupillary responses driven by ipRGCs and classical photoreceptors are impaired in glaucoma

• Published in: Graefe's archive for clinical and experimental ophthalmology Vol. 254; no. 7; pp. 1361 - 1370
• Main Authors: Kelbsch, Carina, Maeda, Fumiatsu, Strasser, Torsten, Blumenstock, Gunnar, Wilhelm, Barbara, Wilhelm, Helmut, Peters, Tobias
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2016; Springer Nature B.V
• Subjects: Adult; Female; Glaucoma; Glaucoma - metabolism; Glaucoma - physiopathology; Humans; Male; Medicine; Medicine & Public Health; Middle Aged; Neurophthalmology; Ophthalmology; Photic Stimulation; Reflex, Pupillary - physiology; Retinal Ganglion Cells - physiology; Rod Opsins - metabolism; Visual Fields; Glaucoma; Colour pupillography; Pupil light reflex; ipRGC; Ocular hypertension
• ISSN: 0721-832X; 1435-702X
• DOI: 10.1007/s00417-016-3351-9

Purpose 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 PIPR blue-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 PIPR blue-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 PIPR blue-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.