There are many causes of pupil dilation, such as dimming of light, motoneuropathy, medications, etc. 1. Physiological reasons: If the light suddenly or gradually dims, it will cause the patient’s pupil to become enlarged. 2. Actinic neuropathy: patients with actinic neuropathy may show symptoms of pupil dilation, loss of light reflex, accompanied by impaired movement of the superior rectus, medial rectus, inferior rectus, inferior oblique muscles, and ptosis of the eyelids. 3. Drug effects: If patients use pupil-dilating eye drops, such as atropine gel, tropicamide eye drops, etc., patients may show pupil dilation, accompanied by photophobia, tearing and other uncomfortable symptoms. It is recommended that patients with abnormally dilated pupils consult a doctor to evaluate their condition and follow the doctor’s instructions for treatment.