High resolution anterior segment optical coherence tomography for differential diagnosis between corneo-conjunctival intraepithelial neoplasia and pterygium

Objective: To assess if anterior segment optical coherence tomography (AS-OCT) is a noninvasive diagnostic method suitable to differentiate benign corneo-conjunctival lesions (pterygium) from premalignant lesions (corneo-conjunctival intraepithelial neoplasia, CIN).

Material and methods: An observational, analytical and cross-sectional study was conducted in 22 eyes with conjunctival lesions clinically suspicious for pterygium and CIN during two years. Morphological differences between both lesions were studied with AS-OCT; epithelial thicknesses (EE) and extension length on corneal surface (GIC) were compared between both groups. A surgical excision of the lesion was performed for histopathological diagnosis.

Results: Mean age of patients with pterygium (n=18) was 52.67±15 y.o and 74±12 y.o in subjects with CIN (n=4) (p<0.021). In pterygia, AS-OCT showed typical features (normal, thinning or slightly thickened EE; 77.4±26μm), in addition to an increase in wedge-shaped subepithelial tissue. Patients with CIN had a mean thickened EE (262.5±124μm) and strongly hyperreflective, with abrupt transition between normal and pathological epithelium. Analysis of EE between subjects with pterygium and CIN revealed statistically significant differences (p<0.002). ROC curve revealed a 100% sensitivity and specificity of OCT-SA in differentiation between CIN and pterygium, using 141μm as cutoff point of EE.

Conclusion: AS-OCT is a useful tool for the differentiation between pterygium and CIN able to provide typical morphological characteristics. An EE greater than 141μm in AS-OCT suggests a sensitivity and specificity of 100% for the diagnosis of CIN.