Tuesday, March 1, 2011

Suppression scotomas - and why I overconverge

Suppression scotomas... I've read about them before, but I didn't really find the subject all that interesting. There's a spot on your retina... where you suppress... or something... blah blah blah... who cares. It didn't really interest me. But last night, while doing my vision therapy homework, I suddenly understood suppression scotomas. And I also realized the reason why I often cross my eyes and overconverge when I'm doing vision therapy exercises.

First, what the heck is a suppression scotoma? A scotoma is an area of your retina where images are suppressed. If an image falls on a suppression scotoma, it is suppressed.


This is me, looking at a diamond. I can see the diamond just fine in my right eye. My left eye is being bad, and shooting off into nowhere. The diamond can still be seen peripherally by my left eye, though, and thus I should see two diamonds. But I don't see two diamonds. I only see one diamond. Why? Because the diamond image from my left eye is falling on a suppression scotoma.

The suppression scotoma is that big green spot. Everything that falls on that green spot is suppressed. This suppression scotoma has been custom made by my eyes and brain to prevent double vision. It perfectly fits the way that I use my eyes in every day life. Things in my central field of vision are suppressed, yet things in my left-hand peripheral field are still visible. I do not experience diplopia.

When I do vision therapy exercises, I desperately try to see the input from both eyes, but I have trouble because there's a big scotoma in the way. I need to break down that scotoma and start using that spot on my retina again. But sometimes... I cheat. I peek around the scotoma. How do I do that? Overconvergence!


In this picture, the dotted lines show where my eyes are pointing. They aren't pointing at the diamond, they are pointing in front of it. This causes the image of the diamond to fall outside of my central vision, and I see two diamonds. More importantly, it causes the image of the diamond to fall outside of my suppression scotoma. I receive input from both eyes (hurray!), but it's a diplopic, misaligned image (boo!). I believe this is why, when doing activities with the red/green glasses, I often see a misaligned image like this:


When I realized that I had been overconverging to peek around my suppression scotoma, I was amazed. Brains and eyes are so smart. And tricky. And lazy. And good at finding shortcuts.

10 comments:

  1. Could you describ your symptoms with the overconverbence? I wonder if I and my daugther have the same problem. Thanks so much!!

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  2. Well, I was only describing my tendency to cross my eyes too much while doing vision therapy exercises. It doesn't really happen to me in my every day life. Are you and your daughter in vision therapy?

    Some people have trouble bringing their eyes together when looking at near objects (convergence insufficiency) and some people bring their eyes together too much while looking at near objects (convergence excess). Both of these can cause eye strain, blurred or double vision, headaches, and poor comprehension while reading. If you think that you or your daughter have trouble with this, you should make an appointment with a developmental optometrist.

    You can locate a developmental optometrist here:

    https://covdwp.memberpoint.com/WebPortal/BuyersGuide/ProfessionalSearch.aspx

    ReplyDelete
  3.  I was recently diagnosed with pd. I thought I had injured my eye removing a contact lens with a sharp index fingernail.Not. But my pd occurs only in my left eye and in the peripheral field, for example when I stop at a light or stop sign and look to the left for oncoming traffic. It makes me very nervous to see double cars and so I close my right eye and hope the oncoming traffic doesn't think that I'm winking flirtatiously at them.

    ReplyDelete
  4. NeverAsk.NeverForgetAugust 12, 2014 at 6:03 AM

    What do you want to talk about UnknownIdentity?

    ReplyDelete
  5. About an alliance. You and my group together.
    You find the basics of the agency in the lv and rep section, when you don't read it already.

    ps: nice place to talk about things like that. ( ̄. ̄)

    ReplyDelete
  6. NeverAsk.NeverForgetAugust 12, 2014 at 9:04 AM

    I quote you:
    "All you can think about. IPs, name of staff, ips of staff, ips of single members,group infos (like amount of members),etc.
    If you have coins, you can pay us for destroying a group or make another person the leader.
    I don't say it is 100% successful, but it is possible we can do that."
    That's what i'm trying to destroy... the games of power... i don't have your methods of communication. Let's find common ground. Skype?

    ReplyDelete
  7. If you fight against our work, there's no way for being allied. So why talk about communication?

    ReplyDelete
  8. NeverAsk.NeverForgetAugust 12, 2014 at 11:29 AM

    The enemy of my enemy is my friend. All men must do sacrifices once in a while. I invited you to try and find common ground. We can unite resources on common goals or stay aside on oposite goals. As i see it, you're trying to give the "noobs" and "dejections" a chance to get justice. I honestly admire your work. That is a goal we have in common. The only difference is i'm doing it to prevent the war, not gain from it. But hey, everyone is entitled to his own personal interests. =)

    ReplyDelete
  9. Wise words from a great man. You have my respect.
    Then, i stay on my goal, you stay on your goal. That's it, discussion finished, i think. Good luck with preventing a HXW. If you need the help of the agency, you know where to write.

    ReplyDelete
  10. NeverAsk.NeverForgetAugust 12, 2014 at 2:02 PM

    I have spies in almost all groups. If you need legitimate intel, ask here. i'll check daily.

    ReplyDelete