Achromatopsia
Introduction:
Achromatopsia “means ‘without color’”(L. R. Windsor, 1999) and is a disorder concerning the development of the cones on the retina. Some of the symptoms that may be presented are: quivering eyes, light sensitivity, difficulty walking, no or few cones, and nystagmus; involuntary eye movement (“genotype assessment,” 2005). Achromatopsia is a recessive inherited disease so in order to acquire this one must inherit a recessive gene from each parent, therefore you must have parents who are: carriers, affected or one of each. However there is a sex-linked version in which the woman needs to be affected or a carrier and the genotype of the man in not important. If one does obtain Achromatopsia they will suffer from near or complete colorblindness, which will affect their ability to drive and go to work and or school; however this is not a progressive disorder and will not lead to complete blindness. This disorder is found throughout the world and in the United States one of every thirty-three thousand people is affected. There are three kinds of Achromatopsia, X-linked (sex-linked), incomplete and complete The X-linked is the rarest and will usually only affect males and occasionally will appear in a woman. Incomplete is also uncommon and will allow the person to see limited amounts of color with better accuracy then complete. Complete Achromatopsia is the most common and presents with complete black and white vision; full colorblindness, and has very little visual accuracy.
Background:
Achromatopsia is caused when the cones on the retina are not developed properly, if at all. Cones are photoreceptors present on the retina along with Rods; cones are responsible for sight in daylight or bright light, rods for vision at night or during times of dim light. Therefore with a lack of cones everything will seem extremely bright and painful; similar to the feeling one gets when coming out of a movie theater into the bright light and being...