People with photosensitive epilepsy have up to a 14% chance of having seizures precipitated by light or pattern. For some epilepsies, colour is an important factor. Individual differences in the effects of coloured light may cause some patients to benefit from spectral filters that in other patients would exacerbate their sensitivity. 
Many factors can lead to Photosensitive Epilepsy (PSE) seizures. These can be from human-made sources such as flicker from fluorescent lights, car headlights, televisions, and fan blades. Additionally, these can be from natural sources such as flicker from sunlight reflecting off waves or interrupted while travelling past rows of trees or railings. 
Visual stress draws together common features between (1) susceptibility to perceptual distortion and asthenopia (visual fatigue), (2) photophobia accompanying migraine, and (3) the light sensitivity shown in photosensitive epilepsy. Research shows that the perceptual distortions are a manifestation of a hyper-excitability of cells in the visual system, localized in the case of photophobia and more widespread in the case of photosensitive epilepsy.  This study concluded that:
The proportion of patients with photosensitive epilepsy who reported beneficial effects from colour light/filters is larger than in the general population.
Coloured filter glasses may provide relief from seizures in some patients with photosensitive epilepsy. They may also offer relief when antiepileptic therapy is not indicated or sufficient.
Coloured glasses may have other beneficial effects such as a reduction of symptoms of discomfort, sufficient to encourage patients to wear their spectacles despite continuing seizures.
In his book Visual Stress  Arnold Wilkins provides the first general and unified theory of visual discomfort. He found that people find some visual stimuli uncomfortable and that these same stimuli induce seizures in patients with photosensitive epilepsy. His work offers insights into visual triggers arising from architectural design, reading, lighting, television, and computer screens. He also describes in details a range of techniques for preventing and treating visual discomfort, ranging from colour therapy to precision tinting of spectacle lenses.
 Harding G, Harding P, Wilkins AJ. Wind turbines, flicker, and photosensitive epilepsy: Characterizing the flashing that may precipitate seizures and optimizing guidelines to prevent them. 2008 Epilepsia 49 (6) 1095-98