Mechanism of fluid leak in non-traumatic corneal perforations: an anterior segment optical coherence tomography study

Aim Non-traumatic corneal perforations (CPerfs) may present with shallow/flat or formed anterior chamber (AC). This study uses anterior segment optical coherence tomography (ASOCT) to ascertain these differences. Method The study included 14 eyes of 13 patients. They underwent high-resolution ASOCT scans at multiple time points, prior to and after cyanoacrylate glueing, between January 2016 and July 2018. A retrospective analysis of over 2500 ASOCT sections and AS photographs was conducted by two independent observers. The findings were correlated with clinical features and diagnoses. Result All patients had documented Seidel's positive sign at the outset. Two groups with distinctive features were identified. In group 1, 'formed' AC, there was hydration of the cornea with lamellar separation of the stroma, intrastromal pockets of fluid, epithelial bullae and an indirect communication between AC and the exterior. In group 2, 'flat' AC, the corneal hydration was less obvious, there were no pockets of intrastromal fluid, no epithelial bullae and a direct communication of the AC with the exterior. After glueing, the stromal hydration resolved, and healing occurred beneath the glue. The glue and corneal blood vessels consistently cast a dense shadow posteriorly on ASOCT. Conclusion ASOCT demonstrates that leaking CPerfs can be indirect or direct. The former is associated with a 'formed' AC and the latter with a very shallow/flat AC. The valvular nature of the communication in indirect perforations allows the AC to maintain its volume despite a continuous leak.