Quantitative Evaluation of Corneal Ulcer Morphology Using Anterior Segment Optical Coherence Tomography: Implications for Management and Prognosis

Abstract

Background: Corneal ulceration is a severe, sight-threatening condition conventionally evaluated using slit-lamp biomicroscopy. However, clinical examination is highly subjective and limited by optical scattering from dense infiltrates and edema, which frequently obscures deep stromal necrosis and impending perforations. Anterior Segment Optical Coherence Tomography (AS-OCT) provides a non-invasive, high-resolution solution to objectively map corneal microanatomy, though standardized quantitative thresholds for guiding surgical management remain inadequately established.

Aim: To evaluate the microstructural features of infectious and non-infectious corneal ulcers using Anterior Segment Optical Coherence Tomography (AS-OCT) and assess its role in improving clinical management, predicting prognosis, and guiding surgical interventions.

Materials and Methods: This prospective longitudinal study was conducted at a Department of Ophthalmology at Indira Gandhi Government Medical College, Nagpur over an 18-month duration. A total of 92 patients with clinically and microbiologically diagnosed corneal ulcers (both infectious and non-infectious) were recruited. The study included patients aged 18 years and older. Patients with perforated trauma or prior corneal grafts were excluded. Main investigations included slit-lamp biomicroscopy, microbiological testing, and AS-OCT imaging at baseline, Day 3, Day 7, Day 14, and Month 1. Data were analyzed utilizing Shapiro-Wilk, Student’s t-test, Chi-square tests, repeated measures ANOVA, and logistic regression analysis.

Results: The mean age of the cohort was 37.4 ± 13.8 years, with a male preponderance (63.04%, p=0.012). Ocular trauma was the primary predisposing factor (60.87%). The etiological spectrum was predominantly bacterial (52.17%) and fungal (38.04%). AS-OCT identified a dense infiltrate pattern in 30.43% of cases and a spongiform pattern in 26.09%. AS-OCT detected a significantly larger mean infiltrate diameter (4.65 ± 1.82 mm) compared to slit-lamp evaluation (3.82 ± 1.54 mm, p<0.001). A baseline AS-OCT Residual Corneal Thickness (RCT) < 250 µm was identified in 30.43% of patients, offering a 75.0% diagnostic gain for impending perforation over slit-lamp examination. Baseline RCT < 250 µm was an independent predictor for surgical intervention (aOR 11.20, p<0.001).

Conclusion: AS-OCT is an objective, high-resolution imaging modality that surpasses subjective slit-lamp biomicroscopy in the structural evaluation of corneal ulcers. Tomographic parameters, specifically an RCT < 250 µm and spongiform necrosis, serve as highly predictive biomarkers for medical failure, enabling timely therapeutic escalation and surgical intervention.