infections
Amebic Keratitis (Eye Infection)
Introduction
Amebic keratitis is a rare infection of the cornea (the clear layer in front of the iris and pupil of the eye) caused byAcanthamoebaspecies, free-living amebas. It usually occurs in people who wear contact lenses. Amebic keratitis causes painful sores on the cornea, and vision is usually impaired. Doctors take a sample of tissue from the cornea to be examined and cultured. Eye doctors remove infected and damaged cells if sores are superficial and treat the infection with biguanide-chlorhexidineor polyhexamethylene biguanide eye drops plus either propamidine or hexamidine eye drops. To help prevent this infection, people should keep their contact lens in a sterile solution and should not wear contact lenses while swimming, in hot tubs, or when taking a shower. (See also Overview of Parasitic Infections .) Free-living amebas are protozoa (single-cell infectious organisms) that live in soil or water and do not need to live in people or animals. Although they rarely cause human infection, certain types of these amebas can cause serious, life-threatening brain infections in addition to amebic keratitis. Amebic keratitis may be progressively destructive. Most (85%) infected people wear contact lenses. Infection is more likely if lenses are worn during swimming or if lens cleaning solution is unsterile. Some infections develop after the cornea is accidentally scratched. 