Can vary from foreign body sensation to severe ocular pain (often out of proportion to the early clinical findings), redness, and photophobia over a period of several weeks.
(See Figures 4.13.1 and 4.13.2.)
Critical
Early: Epitheliitis with pseudodendrites, whorls, epithelial ridges, and/or diffuse subepithelial microcysts. Subepithelial infiltrates (sometimes along corneal nerves, producing a radial keratoneuritis).
Late (3 to 8 weeks): Ring-shaped corneal stromal infiltrate.
NOTE: |
Acanthamoeba keratitis should be considered in any patient with a history of soft contact lens wear, poor contact lens hygiene (e.g., using tap water to clean lenses, infrequent disinfection), and/or history of trauma or exposure to water (swimming, fishing, hot tub use) while wearing contact lenses. Although most patients with Acanthamoeba have a history of contact lens use, some patients do not and these patients often have a delayed diagnosis. Cultures for bacteria are negative (unless superinfection present). The condition usually does not improve with antibiotic or antiviral medications and commonly follows a chronic, progressive, downhill course. Acanthamoeba is important to consider in patients with seemingly unresponsive HSV keratitis, as HSV keratitis usually responds well to appropriate treatment. The diagnosis of HSV keratitis in a contact lens wearer should always include consideration of Acanthamoeba, as the clinical appearance of these two entities can be similar in the early stages of disease. |
Other
Eyelid swelling, conjunctival injection (especially circumcorneal), cells and flare in the anterior chamber. Minimal discharge or corneal vascularization. Coinfection with bacteria or fungi may occur later in the course.
HSV keratitis is first in the differential. See 4.11, BACTERIAL KERATITIS and 4.15, HERPES SIMPLEX VIRUS.
See 4.11, BACTERIAL KERATITIS for a general workup. One or more of the following are obtained when Acanthamoeba is suspected:
One or more of the following are usually used in combination, sometimes in the hospital initially:
All patients:
NOTE: |
Alternative therapy includes hexamidine 0.1%, clotrimazole 1% drops, miconazole 1% drops, or paromomycin drops q2h. Low-dose steroid drops may be helpful in reducing inflammation after the infection is controlled, but steroid use is controversial. |
NOTE: |
Corneal transplantation may be indicated for medical failures, but this procedure can be complicated by recurrent infection. It is best delayed for 6 to 12 months after medical treatment is completed. |
Every 1 to 4 days until the condition is consistently improving, and then every 1 to 4 weeks. Medication may then be tapered judiciously. Treatment is usually continued for 3 months after resolution of inflammation, which may take up to 6 to 12 months.
NOTE: |
|