Prognostic factors for therapeutic keratoplasty in Acanthamoeba keratitis: a retrospective study

Acanthamoeba keratitis (AK) is a rare but vision-threatening infection that often requires prolonged medical therapy. However, a significant proportion of patients still require surgical treatment. The purpose of this study was to identify clinical predictors for the need of therapeutic keratoplasty (TK) in patients with AK.

This was a single-center, retrospective longitudinal study including 51 eyes from 46 patients with AK diagnosed by real-time polymerase chain reaction between March 2010 and October 2022. The primary outcome was the need for TK. Eyes were divided into two groups (TK versus non-TK) and compared regarding demographic features, initial clinical presentation, and anti-Acanthamoeba treatment. Univariable and multivariable analyses were performed using generalized estimating equations (GEE) logistic regression to account for within-patient correlation (two eyes from the same subject).

Fifty-one eyes of 46 patients (71.7% female; mean age 35.3 ± 13.9 years) were included, with a mean follow-up of 39 ± 30.2 months. All cases were associated with contact lens wear. The median time from symptom onset to diagnosis was 22 days. Fifteen eyes (29.4%) required TK. In univariable GEE analysis, older age at diagnosis (OR 1.09; 95% CI 1.03-1.16; p = 0.005) and longer symptom duration (OR 1.03; 95% CI 1.01-1.05; p = 0.011) were associated with TK. Presenting BCVA was significantly worse in eyes requiring TK than in non-TK eyes in the full cohort, but could not be reliably estimated in GEE regression because of quasi-complete separation. In the multivariable GEE model, older age at diagnosis (OR 1.09; 95% CI 1.02-1.17; p = 0.015) and longer symptom duration (OR 1.03; 95% CI 1.003-1.05; p = 0.028) remained independent predictors.

In this cohort of PCR-confirmed AK, nearly one-third of eyes required TK. Older age at diagnosis and longer symptom duration were independently associated with TK, while worse presenting BCVA likely remained a clinically relevant marker of disease severity. These findings highlight the importance of early diagnosis, prompt treatment, and close monitoring of high-risk patients.