Achromatopsia, also known as rod mon-ochromacy, is a congenital and nonprogressive ocular disorder characterized by an absence of functional cone photoreceptors in the retina. Affected subjects usually present in infancy with photophobia, nystagmus, low visual acuity and inability to discriminate colors. Fundus examination is normal, but electroretinography demonstrates absent photopic (cone) responses and normal scotopic (rod) responses. Achromatopsia is rare in the general population and inherited as an autosomal recessive trait. The authors report the first case of achromatopsia in Thailand with complete electrophysiological findings and long-term follow-up (8 years).

Keywords: Achromatopsia, Rod monochromacy, Photophobia, Nystagmus