Comparison of non-invasive diagnostic modalities for ocular surface squamous neoplasia at a tertiary hospital, South Africa

Abstract

Abstract Aims The aim of the study is to assess non-invasive diagnostic modalities for ocular surface squamous neoplasia, when compared to histology.Methods A prospective case-control study was conducted of patients presenting with conjunctival masses to a tertiary eye hospital in Johannesburg, South Africa. Patients completed an interview and had three non-invasive diagnostic tests: optical coherence tomography, impression cytology and methylene blue stain. A biopsy with histology was performed as the gold standard to confirm the diagnosis.Results One hundred and eighty-two conjunctival masses of 175 patients were evaluated. There were 135 lesions identified as OSSN on biopsy and 47 lesions were benign on histology. Optical coherence tomography had a sensitivity and specificity of 87.2% (95% CI: 80.0–92.5) and 75.6% (95% CI: 60.5–87.1) respectively, when an epithelial thickness cut-off of 140um was used. Shadowing was found in 46% of cases due to leukoplakia or increased thickness of the mass. Cytology had a sensitivity of 72.4% (95% CI: 62.5–81.0) and specificity of 74.3% (95% CI: 56.7–87.5). Methylene blue had a high sensitivity of 91.9% (95% CI: 85.9–95.9), but low specificity of 55.3% (95% CI: 40.1–69.8).Conclusion Optical coherence tomography had a high sensitivity and specificity as a non-invasive test for the diagnosis of OSSN in our population.