Anterior segment optical coherence tomography: imaging characteristics suggestive of microbial etiology in infectious...

To evaluate anterior segment optical coherence tomography (AS-OCT) features in infectious keratitis, to characterize possible findings associated with different microbial etiologies, and to assess quantitative changes observed during follow-up.

This retrospective study included 40 eyes of 40 patients diagnosed with infectious keratitis at a tertiary referral center between January 2024 and July 2025, with a minimum follow-up of 6 months. All patients underwent slit-lamp examination, standardized anterior segment photography, and swept-source AS-OCT imaging for follow-up comparability. Corneal scrapings were obtained from all eyes for Gram staining and culture, and polymerase chain reaction was used to support the diagnosis of Acanthamoeba keratitis.

The mean age was 53.6 ± 19.7 years (range, 8-90), with a female-to-male ratio of 23:17. Microbiological culture was positive in 34 eyes (85.0%). Etiologies included bacterial (n = 14), fungal (n = 8), herpetic (n = 5), and Acanthamoeba keratitis (n = 7). On AS-OCT, mean infiltration width and stromal depth were 2199.8 ± 453.2 µm and 461.5 ± 210.2 µm, respectively. Central corneal thickness decreased significantly after treatment (mean paired difference, 240 µm; 95% CI, 189.6-291.2 µm; p < 0.001). Endothelial plaques were observed in 14 eyes (35%), in both fungal and bacterial keratitis. Posterior stromal or endothelial undulation and intrastromal cystic spaces were identified in 2 eyes, both with fungal keratitis.

AS-OCT enables noninvasive, depth-resolved evaluation of infectious keratitis and allows quantitative monitoring during follow-up. A range of features observed on AS-OCT may provide supportive information for etiologic assessment, particularly when microbiological confirmation is delayed or inconclusive.