How should Acanthamoeba keratitis be treated?
MAY 15, 2019
Question:
My sister has recently been diagnosed with acanthamoeba keratitis. I understand treatment is difficult. When treatment fails, does this mean long term permanent pain? If corneal grafts are not successful what is the next step? Would enucleation be the next step? Also, is there concern of infection moving from cornea to inner eye and even to brain?
Answer:
Acanthamoeba keratitis is an infection caused by very tiny organisms that invade the eye. These single-cell organisms are found in water and soil. Anyone can get acanthamoeba keratitis, but it’s more common in those who swim in contact lenses or who don’t properly clean their contact lenses.
It’s very difficult to treat, because as it spreads, the organisms can alternate between actively invading and becoming walled off cysts. In the cyst stage, it is resistant to the penetration of medications. Treatment does not really 'fail', rather patients may need to be on multiple strong medications for months to kill the organisms whenever they switch back to their active stage. Acanthameoba keratitis primarily stays within just the cornea. It is possible to spread inside the eye, but it is extremely rare and has not been reported to spread from the eye to the brain. If someone has a bad infection inside the eyeball, known as endophthalmitis, then enucleation (removal of the eye) is a potential treatment.
Acanthamoeba inflames the corneal nerves and can cause significant pain while the infection is active. Once the infection is eradicated and the inflammation is resolved, the nerve pain should stop. Unfortunately, at this point, many patients have developed significant corneal scarring and distortion causing impairment of vision. If the scar is affecting vision, patients can undergo corneal transplantation for vision rehabilitation. Patients with Acanthamoeba do have a higher risk of transplant rejection, however. If the transplant fails, the patient would continue to have impaired vision and no further treatment would be pursued. If the infection recurs, then they would be retreated with the appropriate medications.