Case Study #3

Bob was a young child with poor vision and photophobia. His VEP acuity was only about 20/200Ė very low for his age. His ERG responses helped make the diagnosis. Bobís cone mediated ERG responses were markedly abnormal. Bobís diagnosis was achromatopsia.

Bob's results on the ERG Bob's results on the ERG

Achromatopsia is a condition in which there is either a low number of cone cells or low function in those cells. The cone cells are responsible for vision in bright lighting and for the perception of color. The closest those with normal vision come to seeing like those with achromatopsia is in very dim lighting, where color perception is diminished and the main vision is provided by the rods, which are responsible for sight in low lighting. The rods are very sensitive to light, which is why Bob was photophobic.

Additional resources for Achromatopsia: