Parasitic Ulcer Treatment Trial Pilot

Acanthamoeba keratitis is a rare eye infection that is difficult to treat. The mainstay of therapy is a biguanide agent such as chlorhexidine, though recent studies have found povidone iodine to be effective for killing acanthamoeba organisms in vitro. Thus, we randomize participants to topical chlorhexidine 0.04% monotherapy (i.e., routine care) versus topical chlorhexidine 0.04% plus topical poviodine iodine 2.5%. The primary outcome is clearance of acanthamoeba from the ocular surface at 4 weeks.

The role of topical corticosteroids in acanthamoeba keratitis is controversial. Topical corticosteroids can promote growth of acanthamoeba, but may also reduce inflammation and vision-threatening complications of infection. Here, we randomize participants who have completed a course of anti-amoebic therapy to one of three groups: early prednisolone sodium phosphate 1% (started at 4 weeks), late prednisolone sodium phosphate 1% (started at 6 weeks) or placebo (started at 4 weeks). The primary outcome will be visual acuity at 6 months.

Trial 1 Inclusion Criteria:

• Smear or culture positive for acanthamoeba
• Age 13 years or greater

Trial 1 Exclusion Criteria:

• Interstitial or viral keratitis on history or examination
• Corneal perforation
• Therapeutic keratoplasty for acanthamoeba keratitis
• Unwillingness or inability to follow-up (e.g., living too far from hospital)

Trial 2 Inclusion Criteria

• Smear or culture positive for acanthamoeba, with 4 weeks of anti-amoebic treatment
• Age 13 years or greater
• Willing to participate in study

Trial 2 Exclusion Criteria

• Interstitial or viral keratitis on history or examination
• Fungus identified on culture and smear after 2 weeks of anti-amoebic treatment
• Corneal perforation
• Therapeutic keratoplasty for acanthamoeba keratitis
• Unwillingness or inability to follow-up (e.g., living too far from hospital)