The causes of photophobia and blurred vision are many and complex. The common ones are iritis, also called uveitis. The pupil of the normal human eye is in an active state, for example, the pupil narrows when walking from a dark environment into a sunny place, while the pupil dilates when walking from a very bright place into a very dark environment, ensuring that the eye adapts to the environment and sees clearly. In severe cases of iritis, the pupil may narrow, leading to post-iris adhesions, restricted iris movement, and painful iris movement when there is sufficient light, leading to photophobia, tearing, and blurred vision. Treatment is usually done by dilating the pupil to prevent posterior adhesions and by giving anti-inflammatory treatment.