Ring-like stromal infiltrate
Normal eye (left) versus Acanthamoeba-infected eye (right)
A. keratitis (AK) is a painful, vision-threatening infection of the transparent outer covering of the eye called the cornea. Fortunately, it is a rare disease, but unfortunately is more common in individuals who wear contact lenses. The symptoms can be similar to other more common eye infections and can last from several weeks to months. If the infection is not treated promptly, it can lead to loss of visual acuity and eventually blindness.
The most characteristic clinical feature of AK is the presence of a ring-like stromal infiltrate. It is thought that it is composed of inflammatory cells such as neutrophils. At first the amoebae are restricted to the corneal epithelium, but as the disease progresses they attack the underlining stroma causing extensive damage. Symptoms of the disease may include photophobia, excessive watering, ocular pain, corneal ring, irritation, redness of the eye, blurred vision, and conjunctival hyperemia.