Cone Dysfunction Syndromes

Abstract

<h3>Introduction</h3> Cone dysfunction syndrome is the term used in the present investigation to designate a generalized disturbance of the cone system resulting in subnormal visual acuity, defective color vision, and absence of the photopic flicker electroretinogram; concomitant signs may include nystagmus and photophobia. The fundus is normal or may show a variety of lesions which cannot be considered pathognomonic of the condition. The bestknown form of the syndrome is congenital and is commonly referred to as total color blindness, monochromacy, or typical achromatopsia—terms which place emphasis upon the severe loss of color vision. Although it is now apparent that the incidence of generalized cone pathology is much greater than previously assumed,^1-3a lack of awareness of the clinical symptomatology has resulted in frequent misdiagnoses. Many of the patients to be reported had earlier diagnoses of optic atrophy, macular degeneration, cerebral pathology, albinism, congenital nystagmus, or merely "unexplained amblyopia." The