Photophobia is a common eye condition, known clinically as “photophobia”, in which the eyes cannot tolerate light stimulation and once stimulated by light, the eyes will not open and tears will flow, which is caused by a variety of reasons. There are several common diseases: 1, corneal diseases: such as keratitis, corneal edema, corneal epithelial abrasion; 2, anterior uveal diseases: the most common is iritis; the above two diseases are the most common causes of photophobia, less common causes are: 1, conjunctivitis (commonly known as red eye), this kind of photophobia is relatively mild; 2, sclerositis, posterior uveitis: some patients with retrobulbar optic neuritis will have 3. congenital aniridia: patients with total color blindness and congenital glaucoma also have photophobia; 4. various causes of pupillary dilation: pupil-dilating medications and eye trauma also cause photophobia. In addition, some non-ocular diseases may also cause photophobia, such as meningitis, subarachnoid hemorrhage, trigeminal neuralgia, and albinism. Therefore, photophobia can be caused by a variety of reasons, not only from eye diseases but also from non-eye diseases.