Electroretinography and pupillary response in migraine

Area of Science:

• Ophthalmology
• Neuroscience
• Visual Science

Background:

• Migraine is linked to visual sensitivities, but underlying biological causes are debated.
• Retinal dysfunction is a potential source of these visual sensitivities.
• Standard electroretinography (ERG) requires pupil dilation, which may mask migraine-related retinal activity due to known pupillary abnormalities in migraine.

Purpose of the Study:

• To compare rod, cone, and retinal ganglion cell function via ERG alongside pupillary response in individuals with and without migraine.
• To investigate retinal function without pupil dilation by adjusting stimulus luminance for constant retinal illumination.

Main Methods:

• Used the RETeval device to perform standard International Society for Clinical Electrophysiology of Vision (ISCEV) protocols.
• Compared ERG responses (rod, cone, photopic negative-response) in 35 migraineurs and 25 controls.
• Measured pupil diameter simultaneously and adjusted stimulus luminance to maintain constant retinal illumination.

Main Results:

• ERG responses were largely similar between groups, except for a smaller a-wave amplitude in migraineurs under specific light conditions.
• Migraineurs exhibited larger pupil diameters, especially in dark-adapted conditions.
• Larger pupil sizes correlated with faster ERG flicker responses in light-adapted conditions.

Conclusions:

• Pupil functioning appears abnormal in migraineurs, particularly under certain lighting.
• These pupillary abnormalities may be associated with an exaggerated response to uncomfortable flicker in migraine.