Thursday, March 10, 2011

Better training mazes for Macula Integrity Tester

(Well, better according to me!)

The Macula Integrity Tester (MIT) is vision therapy device sold by Bernell. Through a phenomenon called "Haidinger's brush", this machine allows you to see exactly where your macula is pointing. When you look into the machine, you see the small Haidinger brush spinning at the exact spot your macula is pointing. It's pretty cool!

The MIT is usually used for treating eccentric fixation (a subject for another post), but I like to use the MIT for general eye control exercises for my jerky left eye. If the Haidiner brush jerks and jumps around, I know that my eye is doing the same thing. If it moves smoothly, I know that my eye is moving smoothly, too.

One activity for the MIT are these training mazes. You look into the MIT and move the Haidinger brush through the maze. For my purposes, I try to make the Haidinger brush move as smoothly through the maze as possible.

I don't really like the mazes that are available, though. They are what are know as "perfect" mazes. They have one and only one solution, and many dead ends.


A maze of this type offers a task: find the correct way out. However, it's not a difficult task and it's often too easy to see the solution. Very few, if any, of the dead end paths of the maze are ever actually traversed, and thus most of the maze is not used. Imagine you were going through this maze and you got to that branch right before the exit. Would you really ever say to yourself, "I see the exit right there, but I wonder what will happen if I turn left and explore this bit over here?" The maze appears to offer a good opportunity to practice eye tracking, but the activity is over too quickly because, again, most of the maze is not used. The maze doesn't deliver what it appears to promise! I would even find myself pretending to get lost in the maze and going down obvious dead end paths, just because I wanted more practice with eye tracking. But I don't want to pretend anymore! I want a better maze!

So I took an hour, played around with a maze making program called Daedalus, and came up with some better mazes. They are "unicursal" mazes, meaning that there is one path through the maze with no branches. Thus, the entire maze must be traversed in order to complete the maze. Every inch of the maze is used! Below is an example of an 8 x 8 maze, the same size used in the original maze above. See how much more eye tracking is required in the new maze? If you quantify it by distance traveled, here is the score. Old maze: 21, New maze: 64.


Compared to perfect mazes, unicursal mazes offer an opportunity to practice eye tracking at greater length. Some might say that I killed all the fun and interest of the maze by removing the "find the solution" element. However, my feeling is this: you can solve mazes any time you want, but you only get so much time to practice fixing your eyes with your optometrist's fancy expensive machine.

I made 8 mazes with increasing levels of complexity. To use these mazes, simply open the .pdf file provided below, print the mazes onto transparencies, cut them out, and throw them in your MIT (because everyone has one just lying around their house, right?). Enjoy!

Unicursal training mazes for the Macula Integrity Tester

3 comments:

  1. Hi Josh,
    I like the idea of the unicursal maze and agree with you that it's much better for eye tracking than perfect mazes. .
    I was really struck when going through vision therapy with how poor my eye aiming initially was. I couldn't keep my gaze stable on anything even the four large numbers on the four corners of a wall used in the Four Corners exercise. And when I looked downward, my whole view oscillated back and forth.
    Of course, this explained why when I read, I tended to miss important small words (like "not") in a sentence, or I skipped lines or reread the same line over and over again.
    Learning to aim my eyes more precisely, first one eye then two, was really the key to my vision therapy. I still work on this at home with more precise and detailed targets and, increasingly, when I look outside at the trees, I see more details in the branches. Everything looks lacier.
    Sue

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  2. I remember reading about that in your book, and thinking that I didn't have that problem. My gaze is quite steady, I thought. I think I even managed to convince my vision therapist that I was just fine in that department, and we skipped over a few good exercises.

    But now I'm discovering that my left eye (the exo, amblyopic one) has a BIG problem with that. When I try to fixate on something, my eye dances around the target, never able to find stability. On some mornings, when my good right eye is covered by the pillow, I even notice the alarm clock jerking back and forth in a nystagmus-like fashion. It's so strange to have such an obviously weak and unstable eye, and yet be totally unaware of it.

    So lately, I've being doing a lot of back-to-basics vision therapy exercises. Like you said, it's very important!

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  3. Dr. Samantha SlotnickAugust 3, 2011 at 6:51 PM

    Great, thanks for this, Josh!  I always thought the MIT mazes were a bit dopey the way they were set up!

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