Abstract
Purpose :
Retinal colobomas result from failure of the fetal fissure to close during embryogenesis, leading to retinal pigment epithelium (RPE), neurosensory retina, and choroidal dysgenesis. The defect is characterized by bare sclera or membranes of undifferentiated RPE tissue. Visual prognosis is determined by the extent of involvement of the macula. Various optical coherence tomography (OCT) models have been used to image posterior segment coloboma and describe its anatomic morphology, often consisting of atrophic neurosensory retina and absent RPE and choroid. Using swept source OCT, biological imaging can reach the 800nm range. This imaging study describes the anatomy of retinal colobomas as depicted with swept source OCT.
Methods :
This is a retrospective review of a series of two consecutive patients with retinal colobomas that were imaged with swept source OCT (Topcon DRI OCT-1 Atlantis, Topcon Corporation, Tokyo, Japan).
Results :
Case 1: Thirty-one year old male with bilateral retinal colobomas inferior to optic nerve has visual acuity of 20/20 in both eyes. Swept source OCT revealed loss of choroid, RPE, and outer retinal layers, and subsequent invagination of inner retinal layers, which appear thickened, into the remaining potential space. The depth of the choroidal defect is shallow, approximately 190 microns in the right eye and without choroidal defect in the left.
Case 2: Forty-year old female with large macular coloboma of the left eye has visual acuity of 20/100; right eye visual acuity is 20/20. On swept source OCT, a large empty cavity is noted below the macula with loss of the outer retinal layers, RPE, and choroid and remnants of disorganized inner retinal elements draped over the coloboma cavity. The depth of the choroidal defect is approximately 1270 microns. Vascular elements, typically seen in the inner retina, are attenuated and difficult to distinguish in the inner retina overlying the coloboma.
Conclusions :
Swept source OCT imaging of these two colobomas were consistent with known embryologic descriptions and histologic specimens, namely atrophy of neurosensory retina and loss of RPE and choroid. With its greater depth capabilities, swept source OCT was able to image the entire lesion, which previously had not been possible. In addition, the use of an accompanying caliper software tool allowed for more accurate approximation of the depth of the defects.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.