Achromatopsia

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  • Topic: Color blindness, Cone cell, Eye
  • Pages : 105 (38579 words )
  • Download(s) : 211
  • Published : May 16, 2013
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1- Introduction
2- What Is It Like to Have Achromatopsia?
3- Inheritance Factors Associated with Rod Monochromacy
4- Parenting Children and Teens with Achromatopsia
5- Getting Diagnosed
6- Experiences with Vision Care Specialists
7- Living with Extreme Light Sensitivity
8- Living with Colorblindness
9- School Experiences
10- Using Adaptive Methods and Adaptive Devices
11- Social and Psychological Aspects
12- Relationships – Dating and Mating
13- Coming to Terms with Terms
1- Activities of Daily Living
2- Orientation and Mobility (O & M)
3- Vocational Experiences
4- Recreation and Sports
5- Networkers Comment on a Variety of Subjects
6- Discovering the Network

1- INTRODUCTION
What is it like to go through life with very poor visual acuity, the lack of color vision, and the most severe form of light sensitivity that can be experienced by the eyes? To have a vision disorder which causes one to experience varying degrees of visual impairment, depending upon the factors of illumination which vary from one place to another?

It is also important to point out that there are greater and lesser degrees of vision impairment among persons diagnosed with achromatopsia. Some have greater sensitivity to light than others, some are totally without color vision while others have a limited amount of color vision, and some have better visual acuity than others.

Achromatopsia affects one birth out of every 40,000, and is more prevalent in societies where the marriage of blood relatives is common: In this instance, frequent intermarriage increases the risk of two sets of defective chromosomes being combined, leading to achromatopsia.| Excerpts from the New York Times Article on Achromatopsia, Nov. 17, 1992Blind, lost in an explosion of whiteness, like a winter traveler staggering through a blizzard, Ms. Futterman and others with rod monochromacy lack cones, the photoreceptor cells in the retina that respond to color and are responsible for day vision. They can see only through the grace of their rods, photoreceptors that control night vision and are extremely sensitive to dim light. Rods are terrific at picking up the weakest of light signals and can detect even a single photon soaring through space, but as the light brightens toward daylight, or the indoor equivalent, the rods quickly saturate into uselessness. For the normal-sighted, the cones pick up where the rods wash out. For those without cones, they simply cannot see above certain brightness; the screen turns to snowy blankness. And, because only the cones possess the red, blue, and green pigments that are sensitive to colors, people with rod monochromacy can, in the best of circumstances, see only varying types of brightness, a palette of silvers and diamonds. “Cones swamp out the rods in normal vision, so this is an excellent way of studying rod function without worrying about cones.This pattern of cone distribution has led her and others to propose that the genetic defect behind the disorder disrupts, not the body’s ability to generate cone cells, but its power to usher those cells to their proper position on the retina, once the cones have been created. Rod photoreceptors are poor at detecting light falling into the red range of the spectrum; rod monochromats not only cannot see the color red, they are relatively insensitive to red light. Thus, glasses are designed to allow in only light that is in the red range of the electromagnetic spectrum, a small fraction of the sun’s overpowering glow.Many with the disorder are proud night owls, who love going out after dark. Even children with the disorder keep vampire hours. Debra O’Bayley of Santa Rosa, California, whose daughter Elise has rod monochromacy, said the child will do anything in order to stay up late. She’ll be up until eleven at night, playing outside, if she can con us into it,” said Ms. O’Bayley. “She’ll play in...
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