Spectral domain optical coherence tomography findings in bilateral peripheral cone dystrophy

Abstract

To report spectral domain optical coherence (OCT) tomography findings in a case of bilateral peripheral cone dystrophy. A 21-year-old man complained of blurred visual fields on the lateral sides of both eyes. The patient's best-corrected visual acuity was 20/20 in both eyes. Fundus examination revealed mild temporal pallor, while fluorescein angiography did not show any abnormalities. Humphrey's visual field revealed a C-shaped scotoma. Photopic electroretinogram (ERG) and 30-Hz flicker revealed decreased cone function; however, scotopic ERG noted a normal response. Multifocal ERG revealed a relatively well-preserved macular area but with reduced amplitude in the peripheral areas of both eyes. On OCT, the photoreceptor inner and outer segment junction and retinal pigment epithelium (RPE) layers were well preserved in both eyes, except for a slight decrease in outer layer thickness. Moreover, on the macular thickness map obtained from Cirrus HD-OCT, a reduction in internal limiting membrane-RPE thickness that correlated well with visual field defects was revealed in both eyes. On the retinal nerve fiber layer (RNFL) thickness map obtained from Cirrus HD-OCT, the superior quadrant showed decreased RNFL thickness; however, thickness in the temporal quadrant corresponded with thickness in the macular area and was normal in both eyes. The OCT of a patient with peripheral cone dystrophy revealed decreased thickness of the macula with well-preserved retinal structures, which may be one of the distinctive features of this condition.