Rod Monochromatism (Achromatopsia)

Adv Exp Med Biol. 2018:1085:119-123. doi: 10.1007/978-3-319-95046-4_24.


Rod monochromatism (achromatopsia) is a congenital cone photoreceptor disorder, which is rare, affecting about 1 in 30,000 individuals. These patients have normal rod function but no detectable cone function; therefore, everything they see is in shades of gray (total color blindness). Patients usually present in infancy with nystagmus and photophobia. Vision is usually about 20/200 or worse; patients have a hyperopic refractive error. Some patients show paradoxical pupillary response; that is, the pupils dilate in bright light. Fundus examination is normal, though pigmentary mottling and atrophic changes may be observed at the macula. Incomplete achromatopsia: Patients in this group have somewhat better visual acuity, about 20/80 to 20/120, with some residual functioning of cone photoreceptors. This milder form allows some color discrimination. Complete achromatopsia: It occurs in about 4-10% of Pingelapese islanders, who live on one of the Eastern Caroline Islands of Micronesia.

Keywords: Achromatopsia; Autosomal recessive; Rod monochromatism.

Publication types

  • Review

MeSH terms

  • Color Vision Defects / physiopathology*
  • Humans
  • Nystagmus, Pathologic
  • Photophobia
  • Retinal Cone Photoreceptor Cells / pathology*
  • Visual Acuity

Supplementary concepts

  • Achromatopsia 3