ACHROMATOPSIA

Abstract

Achromatopsia, or complete color blindness, is a relatively rare anomaly which is usually associated with profound visual disturbances. When this is the case, all the symptoms accompanying the lack of color perception are attributable to complete absence of photopic vision. Since it is the cone mechanism of the retina which mediates photopic vision, it can be concluded either that the cone cells are absent or, if present, are not functioning. Histologic evidence points to the second of these possibilities¹ ; however, little anatomic material has been available. The typical symptoms accompanying achromatopsia include a marked reduction in visual acuity, central scotoma, ocular nystagmus, photophobia and a shift of the spectral visibility curve. Instead of maximum brightness occurring in the yellow region of the spectrum (555 millimicrons), which is the normal photopic peak, it occurs in the green region (510 millimicrons), which is the peak for normal eyes only when low