Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma

Naber, M., Roelofzen, C., Fracasso, A. , Bergsma, D. P., van Genderen, M., Porro, G. L. and Dumoulin, S. O. (2018) Gaze-contingent flicker pupil perimetry detects scotomas in patients with cerebral visual impairments or glaucoma. Frontiers in Neurology, 9, 558. (doi: 10.3389/fneur.2018.00558) (PMID:30042727) (PMCID:PMC6048245)

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The pupillary light reflex is weaker for stimuli presented inside as compared to outside absolute scotomas. Pupillograph perimetry could thus be an objective measure of impaired visual processing. However, the diagnostic accuracy in detecting scotomas has remained unclear. We quantitatively investigated the accuracy of a novel form of pupil perimetry. The new perimetry method, termed gaze-contingent flicker pupil perimetry, consists of the repetitive on, and off flickering of a bright disk (2 hz; 320 cd/m; 4° diameter) on a gray background (160 cd/m) for 4 seconds per stimulus location. The disk evokes continuous pupil oscillations at the same rate as its flicker frequency, and the oscillatory power of the pupil reflects visual sensitivity. We monocularly presented the disk at a total of 80 locations in the central visual field (max. 15°). The location of the flickering disk moved along with gaze to reduce confounds of eye movements (gaze-contingent paradigm). The test lasted ~5 min per eye and was performed on 7 patients with cerebral visual impairment (CVI), 8 patients with primary open angle glaucoma (age >45), and 14 healthy, age/gender-matched controls. For all patients, pupil oscillation power (FFT based response amplitude to flicker) was significantly weaker when the flickering disk was presented in the impaired as compared to the intact visual field (CVI: 12%, AUC = 0.73; glaucoma: 9%, AUC = 0.63). Differences in power values between impaired and intact visual fields of patients were larger than differences in power values at corresponding locations in the visual fields of the healthy control group (CVI: AUC = 0.95; glaucoma: AUC = 0.87). Pupil sensitivity maps highlighted large field scotomas and indicated the type of visual field defect (VFD) as initially diagnosed with standard automated perimetry (SAP) fairly accurately in CVI patients but less accurately in glaucoma patients. We provide the first quantitative and objective evidence of flicker pupil perimetry's potential in detecting CVI-and glaucoma-induced VFDs. Gaze-contingent flicker pupil perimetry is a useful form of objective perimetry and results suggest it can be used to assess large VFDs with young CVI patients whom are unable to perform SAP.

Item Type:Articles
Additional Information:This research was supported by the Uitzicht grant nr. 2016-35 awarded to author AF, the grant included contributions from: Oog Fonds, FP. Fisher-Stichting, LSBS fond and Glaucoom fonds.
Glasgow Author(s) Enlighten ID:Fracasso, Dr Alessio
Authors: Naber, M., Roelofzen, C., Fracasso, A., Bergsma, D. P., van Genderen, M., Porro, G. L., and Dumoulin, S. O.
College/School:College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Journal Name:Frontiers in Neurology
Publisher:Frontiers Media
ISSN (Online):1664-2295
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Frontiers in Neurology 9:558
Publisher Policy:Reproduced under a Creative Commons License

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