Abstract
BackgroundTo establish the effects of stimulating intrinsically-photosensitive retinal ganglion cells (ipRGCs) on migraine severity, and to determine if migraine produces objectively-measured visual field defects.MethodsA randomized, open labelled, crossover study tested migraineurs and normal controls using multifocal pupillographic objective perimetry (mfPOP) with 44 test-regions/eye. A slow blue protocol (BP) stimulated ipRGCs, and a fast yellow protocol (YP) stimulated luminance channels. Migraine diaries assessed migraine severity. Per-region responses were analyzed according to response amplitude and time-to-peak.ResultsThirty-eight migraineurs (42.0 ± 16.5 years, 23 females) and 24 normal controls (39.2 ± 15.2 years, 14 females) were tested. The proportion of subjects developing a migraine did not differ after either protocol, either during the 1st day (odds ratio 1.0; 95% confidence interval 0.2–4.4, p = 0.48) or during the first 3 days after testing (odds ratio 0.8; 95% confidence interval 0.3–2.1, p = 0.68). Migraine days/week did not increase following testing with either protocol in comparison to the baseline week (1.4 ± 1.6 pre-testing (mean ± SD), 1.3 ± 1.4 post-BP, and 1.3 ± 1.2 post-YP; p = 0.96), neither did other measures of severity. Migraine occurring up to 2 weeks before testing significantly lowered amplitudes, − 0.64 ± 0.14 dB (mean ± SE), while triptan use increased amplitudes by 0.45 ± 0.10 dB, both at p < 0.001.ConclusionsStimulating ipRGCs did not affect migraine occurrence or severity. Pupillary response characteristics were influenced by the occurrence of a recent migraine attack and a history of triptan use.
Highlights
To establish the effects of stimulating intrinsically-photosensitive retinal ganglion cells on migraine severity, and to determine if migraine produces objectively-measured visual field defects
Migraine is thought to be associated with cortical spreading depression (CSD) which consists of a propagated wave of profound depression in cerebral cortical neural activity preceded by transient neuronal activation
A previous study conducted by Main et al [13] observed that migraine patients found both short and long wavelengths of light significantly more uncomfortable between attacks compared to normal controls and subjects with tension-type headache
Summary
To establish the effects of stimulating intrinsically-photosensitive retinal ganglion cells (ipRGCs) on migraine severity, and to determine if migraine produces objectively-measured visual field defects. CSD is believed to underlie migraine aura and to be a trigger for the headache pain [1]. A previous study conducted by Main et al [13] observed that migraine patients found both short (blue) and long (red) wavelengths of light significantly more uncomfortable between attacks compared to normal controls and subjects with tension-type headache. Those results were based on purely subjective measures and, overall, a method for objectively assessing ipRGC function in migraineurs would be useful
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