Patients often present to the clinic with bloodshot and tearful eyes, with red eyes accompanied by tearing. Possible diseases include acute conjunctivitis, keratitis, corneal foreign body, and iridocyclitis. Patients with acute conjunctivitis have a large amount of discharge, red and swollen eyelids, and viral infiltration of the cornea, which can present with photophobia and lacrimation. Patients with keratitis have significant foreign body sensation, pain, photophobia, and lacrimation, accompanied by loss of vision and visible lesions on the cornea. In patients with corneal foreign bodies, there is a marked sensation of shyness of the foreign body, along with a history of trauma and an embedded foreign body visible on the cornea, accompanied by inflammatory infiltration around the foreign body. Iridocyclitis can present with pain in the eye, photophobia, tearing, with loss of vision, congestion of the eye, significant pressure in the ciliary body, clouding in the anterior chamber, and reactive changes in the pupil. Therefore, it is important not to take the redness and tearing of the eyes lightly, but to go to the hospital in time to get a clear diagnosis and give symptomatic treatment.