Objective: To investigate anterior segment swept-source optical coherence tomography (AS SS-OCT) findings in ocular surface tumors and simulating conditions.

Methods: AS SS-OCT imaging and histopathologic data pertaining to 92 eyes of 86 cases collected between September 2018 and April 2023 were evaluated.

Results: The 3 most common lesions were conjunctival nevus (18 eyes), ocular surface squamous neoplasia (OSSN, 16 eyes), and pterygium/pinguecula (13 eyes). Excisional/incisional biopsy was performed in 58 of 86 (67.4%) cases. On AS SS-OCT, conjunctival nevi demonstrated mildly hyperreflective epithelium of normal thickness, internal hyperreflectivity, and intralesional cysts. OSSN showed epithelial hyperreflectivity, epithelial thickening, and an abrupt transition between normal and abnormal epithelium. Differences between median maximal epithelial thickness on AS SS-OCT for OSSN and pterygium (560 vs. 102 μm), OSSN and pseudopterygium (560 vs. 113 μm), OSSN and pinguecula (560 vs. 72.5 μm), and OSSN and conjunctival papilloma (560 vs. 965.5 μm) were statistically significant (P < 0.001, P < 0.001, P < 0.001, and P = 0.039, respectively). By receiver-operating characteristic curve, using 630.5 μm as a cutoff, the sensitivity and specificity of AS SS-OCT for differentiating between conjunctival papilloma and OSSN were 69% and 100%, respectively (P = 0.038). The presence of hyporeflective spaces/cysts was statistically significant in conjunctival papilloma compared to OSSN (P < 0.001) and in conjunctival nevus compared to conjunctival melanoma (P = 0.002).

Conclusions: AS SS-OCT is a useful tool in differentiating OSSN from pterygium/papilloma and conjunctival nevus from melanoma. It provides important in vitro information on many other lesions including conjunctival lymphoma, primary acquired melanosis, and conjunctival amyloidosis.