Day Blindness also known as Achromatopsia , or color blindness, is characterized by cone photoreceptor dysfunction, causing severely reduced or complete vision loss during daylight hours. Dogs may also show signs of avoiding bright light or distress in bright light (photophobia), and total colour-blindness. The disease is present at birth (i.e. it is congenital) and clinical signs show when dogs are approximately 8-10 weeks of age.
Day-blindness in bright light, normal vision in dim light. Achromatopsia is an autosomal recessive disease characterized by the loss of cone photoreceptor function that results in day-blindness, total colorblindness, and decreased central visual acuity.
Sidjanin, D.J., Lowe, J.K., McElwee, J.L., Milne, B.S., Phippen, T.M., Sargan, D.R., Aguirre, G.D., Acland, G.M., Ostrander, E.A. : Canine CNGB3 mutations establish cone degeneration as orthologous to the human achromatopsia locus ACHM3 Human Molecular Genetics 11:1823-33, 2002. Pubmed reference: 12140185.