The eye is frequently assaulted by bacteria that cause infection. The defenses of the eye are normally able to keep foreign invaders out. Still, bacterial infections can and do occur both on the surface of the eye and deep inside the eye. Bacterial infections in the eye can be serious and should be examined by an ophthalmologist.
Mechanism
Bacteria enter the eye when the normal protective mechanisms of the eye---the tear film, blinking reflex and benign bacteria that keep dangerous bacteria off the eye---break down, according to "The Handbook of Ocular Disease Management." Harmful bacteria also enter the eye after trauma or surgical procedures that breach the eye's surface. Contact lens wearers may develop keratitis, an infection of the cornea.
Types
Bacterial infection can occur in different parts of the eye, including the conjunctiva, the membrane that covers the lower eyelid, the sclera, the white of the eye, and the cornea, the domed-shaped covering in front of the eye. Bacteria can also penetrate the middle portion of the eye during surgery or trauma, causing a serious infection called endophthalmitis. Bacteria in the bloodstream can travel to the inner part of the eye as well and cause endophthalmitis, the Merck Manual states.
Symptoms
Symptoms of bacterial infection vary depending on the location of the infection. Conjunctivitis causes reddening of the lower lid and front of the sclera, light sensitivity, purulent discharge that may glue the eyelids together especially overnight, itching and discomfort. Symptoms of keratitis include pain in the eye, decreased vision and discharge. Endophthalmitis causes reddening of the eye, serious vision loss and extreme pain and light sensitivity.
Treatments
Treatment for any bacterial infection is antibiotics, but the method of delivery varies depending on the location of the infection. Conjunctivitis and keratitis are treated with antibiotic drops, while deeper infections inside the eye are treated with antibiotic injections into the eye or oral antibiotics. Corticosteroid drops or injections into the eye to reduce inflammation are also often used to treat bacterial eye infections.
Complications
Serious vision loss can occur if infections in the eye aren't promptly and properly treated. Keratitis can lead to corneal scarring and the need for a corneal transplant, the National Eye Institute warns. Endophthalmitis may require surgery to removed infected tissue from in the inner part of the eye.
