Department News

Why does light worsen migraines?  See our Expert Commentary on new findings!
January 2010

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What do our experts think?

The UIC Department of Ophthalmology and Visual Sciences is home to leading experts on basic and clinical research in ophthalmology.  As new finding in ophthalmology and vision science make the headlines, we ask them to share their thoughts.   Recently, a study published in Nature Neuroscience was covered by NPR and other major news outlets.  Our own expert, Dr. Harris Ripps*, breaks it down for us.
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Study of blind individuals helps explain why light exacerbates pain associated with migraine headaches

Most individuals suffering from the debilitating effects of recurrent migraine find some relief in a darkened room, and it was for many years a mystery as to why the throbbing headache, nausea and related symptoms were far more severe in daylight.  However, an exhaustive research study undertaken by Dr. Rami Burstein and co-workers from Harvard Medical School and the Moran Eye Center (University of Utah) have provided us with an in-depth understanding of why light exacerbates the pain, as well as the reason some entirely blind individuals experience the same phenomenon.  

The study, published in Nature Neuroscience, provides a detailed account of the multidisciplinary approach they used to trace and record from tracts in the brains of experimental animals, examine the visual performance of patients with a long standing history of severe migraines, and patients who were blind but continued to experience the persistent, throbbing headaches of migraine.  In the course of their work, they succeeded in identifying the neural pathway that extends from the retinal ganglion cells to a discrete area in the brain (the thalamus) that receives signals from a unique region of the brain’s lining (the dura) from which the pain signals originate. They then could show that these signals were increased by light stimulation, thus forging the link between light and the exacerbation of pain in migraine.

It is important to recall that in sighted individuals, the signals generated by the rods and cones of the retina are transmitted through the retina to ganglion cells whose long axonal branches relay the information to the visual cortex and other centers involved in the visual process.  However, there exists another group of ganglion cells that respond directly to light, transmit signals to another region of the thalamus, but are not involved in image-forming functions. These cells, which govern the 24 hour cycle of daily activity (circadian rhythm) in man and other organisms, survive the destruction of the photoreceptors caused by heredo-degenerative diseases such as retinitis pigmentosa.  And it is photic activation of these so-called melanopsin-containing ganglion cells, that gives rise to the enhanced pain experienced by some blind patients.  Others, on the other hand had lost sight as result of severe damage to their optic nerves, and the intensity of their headaches were unaffected by light. Clearly, the photic exacerbation of migraine pain depends on signals relayed from the retina to the brain via the optic nerve.

*Harris Ripps, D.Sc., Ph.D.
Professor Emeritus

Dr. Harris Ripps is among the leading lights in ophthalmological and vision research.  The author of over 185 original, peer-reviewed articles attests to the magnitude of his contributions to vision science generally and retinal neurobiology in particular. From 1964, when he was awarded a Research Career Development Award from the National Institutes of Health, until his retirement in 2008, Dr. Ripps’ research was continually funded by NIH.  In the course of his career Dr. Ripps was a visiting Professor at the University of London, the Cole Eye Institute of the Cleveland Clinic, and the Pasteur Institute (Paris).  Among his many honors are the Proctor Medal, The Alcon Award, The Award of Merit from the Retina Research Foundation, The Edridge-Green Award of The Royal College of Surgeons of England, and the Distinguished Faculty Award of University of Illinois College of Medicine.