• Distortions in vision perception alter how colors appear within the visual field.colors image by Dwight Davis from Fotolia.com
  
  Light consists of energy wavelengths that appear as different colors within the visual part of the electromagnetic spectrum. Human eyes contain structures called cones and rods that sort out these wavelengths and enable distinctions between colors. Different types of vision perception occur when impairments exist within the cone and rod structures.
  
  

Vision Processes

• Light responses in the eye occur within a neuro-membrane lining called the retina, which sits at the back of the eye. Inside the retina, cones and rods--also known as photoreceptors--enable night vision and color perception, according to the vision reference site Colorblind. The cones process color differences by secreting pigment materials in response to certain light-energy wavelength frequencies, while the rods enable night vision by amplifying existing light sources. Cone receptors are particularly sensitive to variations in the red, green and blue wavelength frequencies. A person's genetic code determines how these photoreceptors work; mild or severe color deficiencies result when cones and rods lack the sensitivity needed to discern wavelength frequencies. When a lack of sensitivity exists, pigment secretions impair a person's ability to distinguish or identify certain colors.
  
  

Dimmed Vision Types

• Brightness and hue determine a person's ability to distinguish different colors and vision capacity weakens when rod structures don't respond to light intensity, according to the Colorblind website. A loss of light intensity can also affect any one of the color receptors or it can affect all three. Protanomaly is a condition where the color red appears weak and dim within a person's visual field. When this happens, the eye's red photoreceptors fail to secrete the needed amounts of pigment. As a result, red colorings become dim or altered. Colors like orange or yellow may appear greenish, while colors like violet and purple appear bluer than they really are. Brightness also plays a role in protanopia, a condition that makes the colors red, yellow and orange appear dim or totally invisible in extreme cases. In effect, the eye can't distinguish between the three colors causing reds to appear as black or grays while pink colors appear as blue.
  
  

Color-Blind Vision Types

• Color-blindness exists as a weakness in color perception caused by the cone structures within the retina. One condition--known as deuteranomaly--exists within the green photoreceptors, which means the retina can't process some or all of the wavelengths contained in green colors. Colors containing green appear reddish or bluish within a person's visual field. This causes individuals problems when distinguishing small differences in hue because of a lack of "green" perception. Problems with hue distinction also play a role in dichromacy and deuteranopia--conditions where reds, yellows and greens all appear as the same color. Individuals with dicromacy can see slight differences between reds, yellows and greens, whereas individuals with deuteranopia see no difference at all between the three.