Color blindness as part of the retinal damage caused by diabetes. Vitamin A deficiency may also cause color blindness. Some subtle forms of color blindness may be associated with chronic solvent-induced encephalopathy (CSE), caused by long-time exposure to solvent vapors. Red–green color blindness can be caused by ethambutol, a drug used in the treatment of tuberculosis. The typical human retina contains two kinds of light cells: the rod cells (active in low light) and the cone cells (active in normal daylight). Normally, there are three kinds of cone cells, each containing a different pigment, which are activated when the pigments absorb light.
Macula of retina Macula of retina The macula or macula lutea is an oval-shaped pigmented area near the center of the retina of the human eye and some other animalian eyes. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas. The anatomical macula at is much larger than the clinical macula which, at , corresponds to the anatomical fovea. The macula is responsible for the central, high-resolution, color vision that is possible in good light; and this kind of vision is impaired if the macula is damaged, for