Abstract
Purpose :
To investigate the chromatic pupillary responses and light-induced lacrimation mediated by intrinsically photosensitive retinal ganglion cells (ipRGCs) in migraine patients with photophobia. We hypothesized that patients with migraine (without evidence of dry eye disease) will exhibit increased ipRGC activities which correlate with increased light-induced lacrimation.
Methods :
Ten individuals with episodic migraine and normal tear production (i.e., no dry eye disease) and eleven healthy controls participated in the study. Following an initial baseline trial (no light flash), participants received seven incremental intensity steps (0.1, 1, 3.16, 10, 31.6, 100, 400 cd/m2) of alternating red and blue light stimuli. Pupillometry recording of the left eye and a 1-min anesthetized Schirmer’s test of the right eye (using 0.5% proparacaine) were performed simultaneously. Two-way mixed ANOVA and Pearson's correlation coefficient were performed for statistical analysis.
Results :
Intrinsic and extrinsic ipRGC photoactivities, as measured by chromatic pupillometry, did not differ between migraine participants and controls across all intensities and wavelengths. Participants with migraine, however, had significantly lower lacrimation following the highest intensity (400 cd/m2) blue light stimulation relative to controls (F(1,19) = 14.34, p = 0.001). There was a positive linear correlation between melanopsin-driven post-illumination pupillary response and lacrimation following blue light stimulation in both groups (Migraine: r = 0.51, p = 0.001; Controls: r = 0.57, p < 0.001).
Conclusions :
Migraine patients with self-reported photophobia have normal ipRGC-driven pupillary response, suggesting that photophobia and pupillary light response may be mediated by two distinct circuits with both originating from ipRGCs. The positive correlation between melanopsin-driven pupillary response and light-induced lacrimation suggests that the afferent arm of the light-induced lacrimation reflex is mediated by melanopsin and functions normally in patients. The reduction in melanopsin-mediated light-induced lacrimation at the highest light intensity level suggests that the efferent parasympathetic pathway of the lacrimation reflex is attenuated under certain conditions, which may be a harbinger of dry eye disease especially in patients with chronic migraine.
This is a 2020 ARVO Annual Meeting abstract.