Intercalary membrane break and detachment causes intrachoroidal cavitation in macular coloboma

To describe the clinical and imaging features in a series of patients diagnosed with macular coloboma (MC) and intrachoroidal cavitation (ICC). Patients diagnosed with MC based on clinical examination between June 2017 and July 2021 were retrieved from the electronic medical record system and were included in the study. Colour fundus photographs, optical coherence tomography (OCT) and Multicolour® imaging scans of these patients were analysed. We identified 16 eyes of 11 patients with MC on fundus examination. Based on OCT imaging features, conforming variant of MC was seen in 9 (56%) eyes and non-conforming variant in 7 (44%) eyes. No eyes with MC in the study showed features of both conforming and non-conforming varieties simultaneously. In the non-conforming variety of MC with presence of intercalary membrane break, ICC was identified in 5 (71%) of these eyes. ICC in MC appeared as flat, dark greenish areas with or without an orange-coloured boundary abutting the margin of the coloboma on Multicolour® imaging. In 31% eyes, ICC was seen in non-conforming type of MC and was well-identified on Multicolour® imaging. It appears that presence of intercalary membrane break and detachment are prerequisites for developing ICC.