Cone dystrophy with supernormal rod response – case report

Abstract

Abstract Purpose Our purpose is to present a case demonstrating a novel, rare retinal disorder, called "cone dystrophy with supernormal rod response". Methods A 31‐year‐old female patient has been suffering from colour vision disturbances since her childhood. Her best corrected visual acuity is 0.2 in both eyes. Beyond routine ophthalmological methods we performed electrophysiological examinations, colour vision tests, dark adaptation, optical coherence tomography, fluorescein angiography and molecular genetic testing. Results Examinations revealed colour vision disturbances, OCT showed macular thinning, FLAG demonstrated enlarged foveal avascular zone. Electroretinography showed extinguished cone function, preserved rod response and supernormal maximal b‐wave. Genetic tests confirmed mutation of the KCNV2 gene. Conclusion "Cone dystrophy with supernormal rod response", known from recent literature, is a rare retinal disease, with the affection of the KCNV2 gene in the genetic background. Its stationery character is rare amongst cone dystrophies, congenital achromatopsia is the only one to have similar manifestation.