Symptoms that literally can not distinguish all colors. One out of every 300,000 color blindness is color blind. The whole world is seen in black and white, and as much as possible is the degree of discrimination. Sharks are among the animals. It is the most rare case of color vision abnormality. If only one of the three cones is left, the world will be recognized as monotone. In this case, there are several cases. If only blue cones are left, there is no blue cones in the center of the retina and in the center, so it looks more blurred than when only red or green is left. When all three cone cells are lost, only the glandular cells will see the world. Only the faint lightness is distinguishable, and the shape is not clearly seen. If there are no glandular cells, the vision is completely lost.