Semilunar sign of cornea: A multimodal analysis of the posterior corneal opacity in non-infectious anterior scleritis

Purpose: To analyze the morphological outcomes of the posterior corneal opacity or “semilunar sign” in noninfectious anterior scleritis using multimodal imaging. Methods: This was a prospective observational case series. Patients with anterior scleritis from January 2018 to January 2019 were included. Clinical and demographic data were collected. Posterior cornea was visualized using the digital slit lamp photography (Elite, mega digital vision), spectral domain optical coherence tomography (MS39), and specular count analyzer (EM-3000). “Semilunar sign” was defined by the (1) presence of posterior corneal opacity, (2) concave semilunar pattern, (3) absence of blood vessels, and (4) normal anterior cornea. Incidence, clinical characteristics and significance, correlation with Mantoux sensitivity, and role of multimodal valuation were assessed. Results: Overall 76 eyes of 72 patients were recruited with anterior scleritis. Fifteen eyes of 11 patients (15.3%) presented with semilunar sign. The scleritis was both nonnecrotizing (n = 8) and necrotizing (n = 7). The semilunar configuration appeared as isolated (n = 9) and continuous lesion (n = 6). The extent was directly related to the scleral disease extent (P = 0.002). The mean thickness measured 212.5 ± 129.3 μm. The mean central endothelial cell density (ECD) was 2540.8 ± 351.7 cells/mm2, which was significantly higher than the involved peripheral cornea (P = 0.05). The mean surface area of the semilunar sign was 7.7 ± 5.2 mm2. There was no significant correlation between the opacity thickness and the best-corrected visual acuity (P = 0.895, r = −0.39), ECD (P = 0.52, r = −0.188), and Mantoux (P = 0.696, r =− 0.142). Conclusion: Corneal semilunar sign of scleritis affected the peripheral cornea and caused no functional abnormality in early presentation. Multimodal analysis can aid in clinical assessment and severity.