Painful red eye usually indicates severe eye problem that need immediate medical treatments attention, as some conditions may cause permanent blindness if treatment is delayed.

Common and important causes of painful red eye include corneal ulcer, acute glaucoma and uveitis.

Corneal ulcer

The cornea is the outermost layer of the eye. It is the clear, dome-shaped surface that covers the front of the eye and helps focus light onto the retina. Corneal infection occurs when bacteria gain entry into the cornea through a scratch or breakdown in the corneal surface. User of extended wear disposable contact lens, has higher risk of getting corneal ulcer.

Corneal ulcer (or infectious keratitis) can cause severe eye pain and redness. Other symptoms include tearing, foreign body sensation, sensitivity to light, and blurred vision. In some contact lens users, the cornea may become somewhat insensitive to pain, and only symptoms of redness and irritation may appear.

A corneal ulcer is a serious, vision threatening problem. Some bacteria can be extremely aggressive, and the cornea can actually perforate (leading to endophthalmitis, or infection within the eye). So, corneal ulcer needs urgent medical attention.

Acute glaucoma

Most people with glaucoma have “open-angle glaucoma”. This type of glaucoma causes no symptoms except for a gradual loss of visual field.

Uveitis

Uveitis refers to a group of ocular inflammatory diseases that affect internal lining of the eye such as the iris, ciliary body, and choroid. This condition lead to symptoms of eye pain, sensitivity to light, pain with focusing, blurred vision, eye redness, and sometimes floaters. One or both eyes can be affected. The eye redness in uveitis is usually a “flush” of redness in a ring around the cornea.

Uveitis is non contagious. Most often, the cause is not known. However, uveitis may be associated with various forms of autoimmune arthritis, systemic infection and malignancy.

Eye doctor can diagnose uveitis through proper examination with special instrument such as slit lamp. This condition needs appropriate treatment and follow. Cases of recurrent uveitis may indicate reason to search for an underlying medical disorder.