Optic disc coloboma with pit treated as glaucoma: diagnostic utility of ultrasound and swept source optical coherence tomography.

Takkar B, et al. BMJ Case Rep 2017. doi:10.1136/bcr-2017-221967 Description A 6-year-old boy presented as a known case of developmental glaucoma and was using topical travoprost in the right eye (RE) since 1 year. Highest recorded intraocular pressure (IOP) was 24 mm Hg in RE, whereas central corneal thickness was 540 μm. Visual acuity was 6/6 in both eyes. On examination, the anterior segment of both eyes was unremarkable. IOP was 16 mm Hg in RE and 20 mm Hg in the left eye. Fundus examination of RE revealed a large and pale optic disc, with a nearly absent inferior neuroretinal rim. The origin of the inferior vascular bundle could not be deciphered, and there was a small atrophic patch inferior to the optic disc (figure 1). A suspicious cavity-like macular lesion was noted adjoining the nasal border of fovea. The fellow eye had a type 3 choroidal coloboma sparing the macula (Ida Mann classification system). Standard automated perimetry showed a large superior arcuate scotoma (figure 1). Swept source optical coherence tomography (SSOCT) of the suspicious lesion showed schisis of the retinal layers nasal to fovea, which could be traced until within the optic disc (figure 1). Optic disc coloboma (ODC) with pit was suspected in RE. Ultrasound of RE revealed an inferiorly decentred excavation within the superficial optic disc tissue, whereas no such lesion was visualised in the fellow eye (figure 2A). SSOCT showed an excavated optic disc with pit confirming the diagnosis of RE (figure 2B). Herniation of the retinal tissue over the pit cavity, vitreous traction and communication of the pit cavity with macular schisis at the temporal border of the optic disc were also noted. Antiglaucoma medication was stopped, and frequent monitoring of IOP and macular status along with laser delimitation of the left eye coloboma was advised. The child is stable until a follow-up of 3 months. Congenital anomalies of the optic disc can mimic glaucoma due to overlapping clinical features and similar visual field defects. Nearly one-third of patients with optic disc pit have visual field defects, the the most common being an arcuate scotoma. Imaging should be used in such doubtful cases for ascertaining correct diagnosis. SSOCT has the ability to provide high-resolution images at deeper tissue levels and is a good tool for imaging ODC with pit. A large SSOCT imaging series on Optic disc coloboma with pit treated as glaucoma: diagnostic utility of ultrasound and swept source optical coherence tomography