Thumb Blocking
Purpose: To develop degrees of freedom in computing visual space
Apparatus: Own thumbs; lenses as prescribed
Method:
1. Patient locks fingers together, arms outstretched with thumbs straight up in front of eyes.
2. Patient is to select a distant target and move thumbs slowly until the right thumb blocks the target from view of the right eye, and the left thumb blocks it from the left eye.
3. At this point, the patient should be aware of three thumbs.
4. He is asked to look through the middle thumb and attempt to see it clearly and in detail while looking across the room.
Aspects to be Emphasized:
1. Ability to maintain awareness and clarity of the three thumbs.
2. Maintain awareness of the total visual space, including the three thumbs.
