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Old 03-24-2006, 02:05 AM   #41
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Join Date: Feb 2006
Location: Stuck in the Matrix somewhere in Santa Clara CA
Posts: 10,197

Originally Posted by jeefreak
well based on the window test it looks like my left eye is dominant. i have a stigmatism in both of my eyes, but my left eye is much worse. does that make sense? my forehands are great and my backhands are crap.
Yes, it is very possible for your dominant-eye vision to be worse than the vision in your non-dom eye. Such is the case for my own eyes. I sustained an injury to my dominant eye some years back. My distance vision recovered in my dominant eye but my near vision has gotten pretty bad in the dominant eye.

Eye dominance is probably established when we are very young. Newborn babies do not see very well at all. We must "learn" to see and make sense of the visual images that we are bombarded with as babies. My guess is that as we learn to make sense of these visual images, the view from one of our eyes becomes the one that our brain choses to be the dominant view. It may be the image from the chosen eye that has some optical superiority or it may be 'cuz of some other physical trait within the optice nerve or within the brain. It could be that muscles associated with 1 eye develops quicker than the other or it can even be largely arbitrary as to which eye is chosen as dominant.

The problems with your backhand may be more as a result with your astigmatism rather than your eye dominance. Or it could be that your backhand problem has less to do with eyesight than it does with stroke mechanics or your stroke timing on the Bh side.

Originally Posted by C_Urala
I just managed to see the 3-d flower. Only, I needed a pensil to help to properly converge my eyes.

BTW it's possible to see the a 3-D image in the picture with rings both far-converged and close-converged. Only in the latter case, the image is not prominent , but bulged-in or stamped and it's less in size.
The use of the pencil is a great idea to force your eyes to close-converge. I was going to suggest using your index finger, but the tip of a pencil sounds like a better idea.

For other that have problems with the "flower" pix, the idea is to get your eyes close-converge on the tip of the pencil. Hold the pencil approx 1/2 way between your nose and the stereo images. Focus & converge your eyes on the tip of the pencil (with the images in the background). You may have to move the pencil closer or further to get your eyes to generate a 3rd image. Keep your eyes converged on the pencil while trying to bring the new image into focus. (Even tho' your eyes remain converged on the pencil tip, the pencil will no longer be in focus if you are doing this properly).

Some ppl will have more difficulty with close-convergence (cross-eyed View) images than with the other type of images (such as the 1st 2 stereograms that I posted). This may or may not be as a result of convergence insufficiency (or some other vergence problem). Best to consult a professional about this.

Some years before 3D stereograms became popular, I sought the aid of a sports vision optometrist for some moderate visual shortcomings. One thing that he found was convergence insufficiency. One of the devices that he used to aid me with my convergence prob was the Brock string. (For a closer look at the device click here). Another convergence aid was the use of 2 pairs of card with the following images:

Figure 1

For figure 1, the eyes are supposed to converge in the distance (so that the eye vergence is almost parallel). If done properly, a 3-D effect will be observed such that the inner (green) circle appears closer than the larger (red) circle. For more on this check out this link.

Figure 2

For figure 2, the eyes should close-converge (use the pencil trick, if needed, to get your eyes to cross). This time the inner (green) circle should appear further (in the background) than the larger (red) circle.
For more about both types of figures check this link.

For an added challenge, try to switch back and forth between parallel viewing & cross-viewing (note that the images above can actually be seen using either vergence method). Try to keep the 3-D effect intact while moving your head left & right for each type. Try moving further & nearer to the screen while keeping the derived image from getting doubled or distorted.

For a a more advanced challenge, print out 1 or both of the above images (make them a little larger if your prefer). Cut each of the printed figures up the middle. You can now physically very the distance between the left eye circles and the right eye circles. For a given seperation, first get your eyes to generate the proper 3D image. Once you've got the 3D image locked, vary the seperation while continuing to maintain that 3D image.

See if you can get your hands on a Brock string so that you can perform some focus & vergence eye training on your own. With the 3 beads at various distances try to jump quickly from 1 to another. With each jump, converge & focus on the new bead a cleanly (& quickly) as possible.

For more stereograms also check out the links mentioned previously as well as EyeTricks. Also google on "stereograms" for more. For other types of visual exercises take a look at post #2 and post #12 (coming soon) on my Improving RT & Visual skills thread.
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