Cone Rod Dystrophy
Inherited Eye Problems
Cone rod dystrophy is evidenced by deterioration of photoreceptor cone and rod cells. It is expressed as a number of inherited eye problems, caused by genetic changes in proteins necessary for proper functioning of the photoreceptors. The cones and rods transform light into electric nerve messages that transfer to our brain via our optic nerve. Cones are the photoreceptor cells which allow us to see fine details and color and comprise our central vision. Rods are for low light vision and permit night and peripheral vision. The malfunctioning photoreceptor cells be problematic starting in childhood, or may degrade with time.
Cone dystrophy refers to a number of rare eye disorders where the cone cells suffer degredation. Stationary cone dystrophy symptoms appear early in life and remain more or less stable. Progressive cone dystrophy symptoms tend to get worse over time. Symptom severity and speed of onset can vary greatly from person to person. Some researchers use the term cone dystrophy to refer only to the progressive form of the conditions. The genetic code controls the iodpsin pigment in the cones which helps protect them.
The stationary form of cone dystrophy is called achromatopsia, meaning vision which lacks color, even though not everyone with this condition is unable to see color. But what does happen is that poorly functioning cone cells cause rod cells to be subjected to too much light. In bright light the vision may appear to be washed out and blurry although the person may be comfortable in darker lighting conditions. Complete blindness does not generally result but patients are often considered legally blind.
Cone dystrophy affects the user's ability to see:
- things that are still
- fine details of things in daylight
- objects in color
- things in fine detail including reading, looking at photographs and recognizing faces
Both the cone and rod cells can be affected by genetic mutations - not only the cone cells. Mutations in genetic code undermine the functioning of protective rhodopsin pigment in the rods. As rod cells deteriorate then the user has increasing difficulty seeing:
- things that move but only in black and white
- seeing in the dark
- seeing things on the sides of us (peripheral vision)
- gradual loss of night vision
- gradual loss of peripheral vision
- sensitivity to bright light
- vision is best at dusk
- errors in color vision in both red-green and blue-yellow ranges
In young children:
- Parents may notice Nystagmus, which are rapid movements of the eyes back and forth from side to side, and/or
- their child's eyes appearing to slowly wander around not focused upon any object, and/or
- the child touching her eyes with her fingers as though she were poking them.
Parents will often notice these signs by the way the child acts.
There are many different causes of cone rod dystrophies. Often one does not know why a child has
the condition. When no cause can be identified this is called Idiopathic.
Most cone rod dystrophies are genetically based and result from "misprints" in a child's genes, and are typically carried forward from the parents' genes although sometimes by chance a new mistake occurs in the child's genes and the parents' genes are normal.
Cone-Rod Dystrophy News
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Also known as: Retinal Cone Degeneration or Dystrophy,