Linked from
The 8 pages that link to Photophobia, each with the reason it gives.
AlbinismRelated: Reduced iris and retinal pigmentation can increase light scatter and discomfort.
AchromatopsiaRelated: Poor cone function leaves bright environments especially uncomfortable.
Corneal ulcerRelated: Corneal inflammation commonly makes light painful.
KeratitisRelated: Inflamed corneal nerves and associated eye irritation commonly make light painful.