[Photophobia: Etiologies and pathophysiology]

Photophobia is an abnormal intolerance to light, which can cause discomfort or even ocular pain. It can result from several causes, including ophthalmological conditions such as keratitis, uveitis, certain retinopathies, and optic neuropathies, which directly affect ocular structures. Neurological disorders, such as migraines, meningitis, or head trauma, may also be causative. Additionally, psychiatric disorders such as anxiety or depression can contribute to the onset of photophobia, highlighting the close links between sensory perception and psychological state. The pathogenesis of photophobia is based on excessive stimulation of neural circuits involved in light modulation and pain perception, with a predominant role of the nociceptive pathway carried by the trigeminal nerve, visual information transmitted by intrinsically photosensitive retinal ganglion cells, and thalamic and cortical relays. Photophobia represents a significant diagnostic challenge, and understanding its mechanisms, along with the precise identification of its cause, is essential to ensure appropriate targeted management.