Abstract
The intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin, which is sensitive to blue light. Previous chromatic pupillometry studies have shown that the post-illumination response is considered an indicator of the melanopsin activation. The aim of this study was to investigate the ipRGC mediated pupil response in patients with a unilateral non-arteritic anterior ischemic optic neuropathy (NAION). Consensual pupil responses during and after exposure to continuous 20 s blue (470 nm) or red (660 nm) light of high intensity (300 cd/m2) were recorded in each eye for 10 patients. Comparisons were performed both intra-individually (affected versus non-affected eyes) and inter-individually (compared with healthy controls). The pupil response was calculated both during the illumination and during the post-illumination phase. The pupil responses to blue and red colors were significantly reduced in the NAION-affected eyes, compared with the fellow non-affected eyes. When comparing the affected eyes with the healthy control eyes, the post-illumination responses were not significantly different. In addition, the post-illumination pupil responses after blue light exposure were increased in the fellow non-affected patients’ eyes, compared with the healthy controls. However, significance was only reached for the late post-illumination response. In conclusion, chromatic pupillometry disclosed reduced post-illumination pupil responses in the NAION-affected eyes, compared with the non-affected fellow eyes, suggesting dysfunction of the ipRGCs. Compared with the responses of the healthy controls, the blue light post-illumination pupil responses were similar in the affected eyes and increased in the fellow non-affected eyes. This suggests a possible adaptive phenomenon, involving the ipRGCs of both eyes after unilateral NAION.
Highlights
Pupil light responses are mediated by the intrinsically photosensitive retinal ganglion cells
The exclusion criteria were: a history of glaucoma, isolated raised intraocular pressure (IOP), cataracts, retinopathies, associated ophthalmologic conditions interfering with the pupil light responses or their recordings such as congenital or acquired iris defects, anterior segment abnormalities, and ptosis
Ten patients with typical, strictly unilateral non-arteritic anterior ischemic optic neuropathy (NAION) were included in the study
Summary
Pupil light responses are mediated by the intrinsically photosensitive retinal ganglion cells (ipRGCs). Pupillometric measurements have been shown to be a potential tool to assess ipRGC function in vivo in humans (Gamlin et al, 2007; Kardon et al, 2009; Feigl et al, 2011; Kankipati et al, 2011; Park et al, 2011; Herbst et al, 2012; Léon et al, 2012). As the ipRGCs integrate information from rods (stimulated by dim blue light) and cones (stimulated by longer wavelengths) (Dacey et al, 2005; Güler et al, 2008), the pupil response reflects both melanopsin and classical photoreceptor activation, based on the stimulus conditions (Kardon et al, 2009, 2011; McDougal and Gamlin, 2010; Park et al, 2011; Gooley et al, 2012; Léon et al, 2012)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
