We describe a 45-year-old man with bilateral bifoveate retinas, an exceptionally rare human phenotype. Spectral-domain OCT demonstrated two distinct foveal pits per eye: a deep central fovea and a shallower temporal fovea with grade 1 foveal hypoplasia features. OCT-angiography revealed paired foveal avascular zones bilaterally. Unlike previously reported cases, which were predominantly unilateral and nonfunctional, both temporal foveae in this case show well-developed architecture closely resembling the bifoveate visual system of Anolis lizards. We propose this represents a rare partial failure of the spatial constraints that normally confine CYP26A1-mediated retinoic acid signaling to a single foveal locus in primates.
Kumar et al. (Thu,) studied this question.