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Question about cause of certain RP symptoms (rblind.com)

submitted 1 year ago by [email protected] to c/[email protected]

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Wondering if anyone actually knows (that is, not just guessing) why RP causes decreased contrast in one's remaining central vision. I asked my retina doc and got an obviously BS answer that cones can't distinguish contrast as well as rods. I am not a fan of doctors who don't have the phrase "I don't know" in their vocabulary. I also googled and came up with a zip. FYI, I'm asking only because I'm curious. With me, the lack of contrast has existed since probably around the time I was diagnosed, it has progressively gotten worse as my vision has deteriorated. In the distant past I was a biologist, and I just can't figure out why retinal changes would cause this. Seems more like something that would be caused by problems with the lens or cornea

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[–] [email protected] 1 points 1 year ago

Two types of light receptors in retina.

One, called cones, addresses color. Distinguishes gross changes in color across entire visible spectrum. More durable, mostly in macula (central vision), and slow to detect change.

The other, called rods, address intensity (brightness). Distinguishes fine changes in light intensity normally presented in gray scale (shades of black and white). More fragile, mostly in prepheral retina, quickly detects change.

RP and Choroideremia tend to kill off the rods in the peripheral retina first eventually moving on to the cones centered in the macula. Fewer rods mean less ability to discerned between changes in shades of color. For example it may be difficult between ruby red and infra red crayons when right next to each other but much easier when separated by florescent yellow.

Or at least that's the gist of the what I remember from a conversation with a low vision occupational therapist. Can't really see enough to test it any more.

High contrast is key for anything you need to see right now.

Be careful trusting what you see. Movement, distance, and definition (shape) perception could be off as well