Detection and Measurement of Hypopyon on Slit Lamp Examination Versus Anterior Segment Optical Coherence Tomography

Purpose: To compare hypopyon detection using anterior segment optical coherence tomography (ASOCT) versus slit lamp examination (SLE) in microbial keratitis, and to evaluate intra- and inter-grader agreement for ASOCT hypopyon measurement. Methods: Two masked graders independently evaluated ASOCT images for hypopyon presence or absence in eyes with microbial keratitis, with disagreements resolved by consensus. A subset of hypopyon eyes underwent triplicate height measurement using two methods (endothelial length and vertical height). The proportion of eyes with hypopyon, Cohen's kappa, and intraclass correlation coefficients (ICCs) were calculated comparing diagnostic performance of ASOCT versus SLE. Results: Inter-grader agreement for hypopyon detection on ASOCT was excellent (κ = 0.94; 95% CI 0.84-1.00) and intra-grader agreement was excellent (κ = 0.89-1.00). ASOCT detected hypopyon in 67.1% of eyes versus 57.0% by SLE. Using ASOCT consensus grading as the reference standard, SLE demonstrated a detection proportion of 83.0% (95% CI, 71.4-92.1%). Intra-grader reproducibility was excellent for both endothelial length and vertical height measurements (ICC 0.977-0.996). Inter-grader agreement was good for endothelial length (ICC 0.831) and vertical height (ICC 0.827), though a statistically significant inter-grader bias was identified for vertical height only (Wilcoxon exact p = 0.006). Conclusions: Among eyes with gradable ASOCT images, ASOCT detected a greater proportion of hypopyon than SLE and demonstrated excellent intra-grader and good inter-grader measurement reproducibility. Endothelial length showed slightly superior inter-grader concordance to vertical height measurement.