Sporadic Variant of Cone-Rod Dystrophy-20

Abstract

Cone-rod dystrophy (CRD) is a group of inherited eye disorders that affect the light sensitive cells of the retina called the cones and rods. A 22-year-old male with no significant family history of ocular disease presented with a 5-year history of progressive bilateral vision loss, photophobia, and difficulty recognizing colors. He reported worsening central vision and mild nyctalopia over the past year. Systemic review was unremarkable, with no neurological or developmental abnormalities. Best-corrected visual acuity (BCVA) was 20/200 in the right eye (OD) and 20/200 in the left eye (OS). Fundus examination revealed bilateral macular atrophy, peripheral retinal pigment epithelium (RPE) mottling, and mild arteriolar attenuation. Optical coherence tomography (OCT) demonstrated diffuse thinning of the outer retinal layers, loss of the ellipsoid zone (EZ), and focal disruptions in the photoreceptor outer segments. He was diagnosed as Homozygous Cone-rod dystrophy-20, c.934delA variant which is autosomal recessive in nature by genetic testing.