Multimodal imaging of a case of peripheral cone dystrophy

To characterize the peripheral cones in the images obtained by spectral-domain optical coherence tomography (OCT), swept source OCT, and adaptive optics fundus camera in a patient with peripheral cone dystrophy.

A 28-year-old Japanese man underwent detailed ophthalmic evaluations including high-resolution imaging of the fundus of both eyes.

The decimal best-corrected visual acuity was 1.2 in both eyes. The results of slit-lamp biomicroscopy and ophthalmoscopy were essentially normal. Fluorescein and indocyanine green angiographies did not show any hyper- or hypofluorescent areas of the retina. Goldmann perimetry showed full peripheral visual fields but relative central scotomas within the central 20°. The results of the Humphrey Visual Field Analyzer showed a limited preservation of the central sensitivity. Color vision tests showed no errors in both eyes. Spectral-domain OCT showed attenuation of both the ellipsoid and interdigitation zones throughout the macular region except the center of the fovea. The scotopic full-field ERGs were normal, but the photopic ERGs were markedly reduced. Regular cone mosaics were not observed especially more than 450 μm radius from the fovea in the adaptive optics retinal images. The parafoveal cone densities were severely decreased in both eyes.

Our findings indicate that the peripheral cone dystrophy diagnosed by full-field ERGs and perimetry is due to a reduction in the density of parafoveal and peripheral cones.