Abstract Details

Title Melanopsin and Cone Stimulation Both Contribute to Interictal Light Sensitivity in Migraine

Topic Headache

Presentation(s) S47 - Headache 2 (2:24 PM-2:36 PM)

Poster/Presentation
Number 008

Objective To measure visual discomfort and squint in response to melanopsin and cone stimulation in headache-free controls and individuals with migraine.

Background Photophobia is a canonical feature of a migraine attack, but light sensitivity often exists interictally. Daylight perception is mediated by cones, which relay information to retinal ganglion cells; a small subset of these contain melanopsin making them intrinsically photosensitive (ipRGC). The relative contribution of these photoreceptors to light sensitivity is unknown.

Design/Methods Following a pre-registered protocol (https://osf.io/qjxdf/), subjects were recruited into three groups: headache-free controls, migraine without aura (MwoA), and migraine with aura (MwA) (n = 20 per group); non-photophobic migraineurs were excluded. Subjects were presented with 4 sec pulses of light that selectively stimulated melanopsin (Mel) or cones (LMS) via silent substitution at 100%, 200% and 400% contrast levels. For each trial, subjects reported visual discomfort (0-10 scale) while squint was concurrently recorded with electromyography of the orbicularis oculi.

Results All groups reported a graded response to increasing contrast levels with 400% contrast eliciting the greatest degree of visual discomfort for both melanopsin and cone stimulation. At 400%, migraineurs perceived greater visual discomfort from melanopsin-directed (MwoA: 5.00; MwA: 4.00) and cone-directed (MwoA: 5.50; MwA 4.00) stimulation as compared to controls (Mel: 2.00; LMS: 2.75). However, only MwA subjects showed increased squint in response to melanopsin-directed (1.88) and cone-directed (1.89) stimulation at 400%. Conversely, squint was not observed in MwoA (Mel: 1.24; LMS: 1.18) and control (Mel: 1.26; LMS: 1.35) subjects at 400%. Data are reported as median values.

Conclusions In photophobic migraineurs, both melanopsin and cone stimulation evoke an explicit report of visual discomfort. An implicit measure of squint response, however, is only seen in migraine with aura for these stimuli. These results suggest that multiple pathways carrying ipRGC signals contribute to photophobia, and that these are differentially affected in migraine subtypes.

Authors/Disclosures
Eric Kaiser, MD, PhD (Hospital of the University of Pennsylvania) PRESENTER	The institution of Dr. Kaiser has received research support from Amgen. Dr. Kaiser has received intellectual property interests from a discovery or technology relating to health care.
	No disclosure on file
	No disclosure on file
Brett L. Cucchiara, MD (Hosp Uni of Pennsylvania)	Dr. Cucchiara has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Elseiver. Dr. Cucchiara has received personal compensation in the range of $5,000-$9,999 for serving as an Expert Witness for Bayer. Dr. Cucchiara has received publishing royalties from a publication relating to health care.
	No disclosure on file
Geoffrey K. Aguirre, MD, PhD (University of Pennsylvania, Department of Neurology)	Dr. Aguirre has received stock or an ownership interest from Nia therapeutics. The institution of Dr. Aguirre has received research support from Lion's Foundation. The institution of Dr. Aguirre has received research support from National Institutes of Health. The institution of Dr. Aguirre has received research support from Johnson and Johnson. The institution of Dr. Aguirre has received research support from Department of Defense.

��ɫ��

��ɫ��