Chorioretinal coloboma is a congenital anomaly which can be present in a clinical spectrum with a possibility of significant influence on visual acuity. Optical coherence tomography (OCT) has been frequently used for the study of chorioretinal coloboma. OCT angiography (OCTA), as a non-invasive method of taking high-resolution images of chorioretinal vessels, can improve our understanding of developmental aspects of this anomaly.
This observational case series evaluated patients with chorioretinal coloboma, who were referred to the eye clinic of a university-based hospital between March 2018 and October 2019. All patients underwent comprehensive ocular examination, OCT, and OCTA using AngioVue technologies from the colobomatous sites.
This study included OCTA imaging of five patients (six eyes) with chorioretinal coloboma lesions. Large retinal vessels, which were intact in all eyes, coursed through the coloboma in four cases and around the margin of the involved area in one case. Attenuation of the microvasculature in the vicinity of coloboma with various extents from nearly normal to severe attenuation was evident in OCTA. Five eyes of four patients had disorganized superficial vessel plexus. Also corkscrew vessels were found in one eye.
This is the first study assessing the vascular pattern in the vicinity of chorioretinal coloboma using OCTA. OCTA revealed nearly normal to severely attenuated retinal microvasculature. At the same time, intact large retinal vessels at the level of superficial vessel plexus coursed across or around the coloboma. OCTA imaging adds new insights about vascular characteristics in the vicinity of these lesions.

Five eyes of four patients were studied to analyze the structure of the inner wall of optic and chorioretinal colobomas using swept-source optical coherence tomography (SS-OCT). The colobomatous cavities and their relationship with adjacent structures were examined. SS-OCT permitted the study of the colobomatous cavities in all cases. In four of those cases, a Y-shaped intercalary membrane (ICM) was identified, with an origin in the retinal nerve fiber layer (RNFL), which covered the coloboma and in one case the coloboma was in contact with the vitreous cavity. Vitreous adhesion to the internal wall of the coloboma was found in three cases. No clinical or tomographic maculopathy was observed in any patient. High-resolution deep penetration SS-OCT allows in vivo study of optic and chorioretinal colobomas, identifying the RNFL as the main component of the ICM overlying the colobomatous cavities.