Transscleral filtration revealing a chorioretinal coloboma

PURPOSE: We report the case of a 19-year-old patient who presented with an ocular hypotony due to a transscleral filtration through an isolated congenital chorioretinal coloboma in his right eye. OBSERVATIONS: The initial examination showed a decimal best corrected visual acuity (BCVA) decreased to 0.7 and a marked hypotony. A localized infero-nasal chemosis and a conjunctival hyperemia were observed. The fundus examination showed chorioretinal folds and an edematous disc. In the infero-nasal retinal periphery, a chorioretinal coloboma was seen with a full-thickness scleral defect. Ultrasound biomicroscopy showed the area of the coloboma through which the percolation of fluid occurred. CONCLUSIONS AND IMPORTANCE: A favorable outcome was observed within 6 weeks and BCVA improved to 1.0 three months later. The intraocular pressure (IOP) increased to 11 mmHg, but the bleb-like filtration could still be seen together with some persistent chorioretinal folds. Ultrasound Biomicroscopy (UBM) imaging was helpful to understand the mechanism of this uncommon complication of a coloboma.