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Nicole Ann Carnt, Dana Robaei, Darwin Minassian, John Kenneth George Dart; Acanthamoeba keratitis in 194 patients: risk factors for poor outcomes and severe inflammatory complications. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4796.
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© ARVO (1962-2015); The Authors (2016-present)
The majority Acanthamoeba Keratitis (AK) cases resolve within 3-6 months with minimal vision loss, however others have a protracted disease course, severe inflammatory complications and debilitating vision loss. Determining characteristics of AK patients with poor outcomes is key to better management.
A retrospective records review of AK cases treated at Moorfields Eye Hospital between 1991-2012 was conducted. AK cases with poor outcomes were defined as those having one or more of the following features: corneal perforation, keratoplasty, other ocular surgery (except biopsy), duration of antiamoebic treatment (AAT) of 10.5 months or more (based on 75th percentile of whole sample) and final VA ≤20/80 attributed to AK. Severe inflammatory complications were defined as scleritis and/or stromal ring infiltrates.
Those with poor outcomes were more likely to be older (median 38 vs. 31 years, p<0.001), had longer symptom duration (median 37 vs. 15 days, p<0.001) and more visits prior to AAT (median 4 vs. 2, p=0.004). Herpes Simplex Keratitis (HSK) treatment and corticosteroids were prescribed more often to poor outcome cases prior to AAT (60/86 70% vs. 36/99 36%, p<0.001, and 56/83 68% vs. 35/98 36%, p<0.001, respectively). Poor outcome was not affected by prior bacterial keratitis (BK) treatment (52/82 63% vs. 57/99 58% exact p = 0.449).At the start of AAT, ring infiltrates (34/87 39% vs. 14/100 14%, p<0.001) and hypopyon (19/83 23% vs. 8/100 8%, p=0.006) were associated with poor outcomes. There was no significant difference in the proportion of cases that had scleritis at start of AAT (6/70 9% vs. 5/96 5%, exact p = 0.523).A higher proportion of poor outcome cases developed culture proven BK (22/90 24% vs. 12/99 12%, p=0.036), scleritis (30/70 43% vs. 4/96 4%, p<0.001) and raised IOP (21/93 23% vs. 2/98 2%, p<0.001) during AAT.After adjustment for confounding effects of HSV treatment and corticosteroid use, older patients were 2.36 times more at risk of a severe inflammatory reaction (95% CI: 1.21 – 4.57, p=0.011) compared to younger patients.
Prompt, anti-amoebic treatment in AK is essential to provide the best chance of a good outcome. Patients who are older, present with more advanced disease and develop complications are more at risk of increased morbidity from AK.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Scleritis and stromal inflammation in a severe case of Acanthamoeba Keratitis
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