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

PURPOSE: 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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.