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

PURPOSE: 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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.