This 60YO female was referred for asymptomatic unilateral fundus findings in her right eye. Vision was 20/30 OD.
Optos color RG imaging shows a choroidal coloboma just inferior to the disc, giving the appearance of a pseudoduplicated optic nerve. Coarse pigmentary changes with some pigment migration extend from the macula into the inferior midperiphery. An inferotemporal retinal vein drains directly into the choroid through the coloboma. Triton swept-source OCT shows that the coloboma overlies an area of ectatic sclera. Fundus autofluorescence (FAF) shows variable hypo-FAF within the area of clinical pigmentary changes, with a surrounding rim of hyper-FAF.
Learning Points:
Choroidal colobomas are most often due to failure of the optic vesicle and choroidal fissure to close during fetal development. Lesions like this may also be from other causes, including toxoplasmosis. Choroidal coloboma can present as solitary or multiple lesions. Visual prognosis depends on the location and involvement of the optic nerve and macula.
Pseudoduplication of the optic nerve occurs when a round choroidal coloboma or chorioretinal scar about the size of the optic nerve is associated with overlying radiating blood vessels (Bloom et al, Retinal Cases 2022;16:174-176). In our experience, it is most common for toxoplasmosis scars to be located near the optic nerve.
Under normal conditions, the retinal and choroidal circulations remain separate and distinct. Rarely, the two circulations connect directly through a chorioretinal anastomosis. These can occur in chorioretinal scars (typically from inactive toxoplasmosis lesions), in macular telangiectasia, and in disciform scars.
The prominent gutter of inferior pigmentary changes indicates a prior retinal detachment, most likely related to spontaneously resolved fluid associated with the coloboma (Tanaka et al, Ophthalmology Retina 2021;5:702-710). Similar pigmentary changes are seen in central serous retinopathy, although our patient’s macular OCTs showed no pachychoroid features (not shown). Finally, this may represent previously resolved pit-like macular fluid, which is rarely found in the absence of a pit or severe glaucomatous cupping (Fujimoto et al, Ophthalmology Retina 2023;7:811-818).
