Iridochorioretinal coloboma associated with buried optic nerve drusen: a case report

Improper closure of the embryonic fissure results in ocular coloboma. Optic nerve head drusen are hyaline deposits located anterior to the lamina cribosa that grow and calcify over time. It is rarely associated with ocular coloboma, with only two cases reported. We present a patient with an irido-chorioretinal coloboma, poorly defined optic nerve limits in the right eye, and increased papillary vascular ramification and peripapillary atrophy in the left eye, without any visible drusen. Fundus autofluorescence, high-resolution optical coherence tomography, and B-scan ultrasonography confirmed the diagnosis of bilateral buried optic nerve head drusen. The association between irido-chorioretinal colobomas and optic nerve drusen in the absence of a systemic disease is exceptional. Our case demonstrates that multimodal imaging is important to correctly diagnose buried optic nerve head drusen.