What is important for the stereo testing with the book?

For stereo testing with a book, it is important to have the stereo glasses placed over the patient's corrective lenses. This ensures that the visual information is properly processed for depth perception, which is the primary goal of stereo testing. The stereo glasses are designed to create a three-dimensional effect by presenting slightly different images to each eye, allowing the brain to interpret depth.

By placing the stereo glasses over the patient's correction, you ensure that the patient is able to see clearly while still experiencing the effect of the stereo test. This setup effectively combines the necessary correction for refractive errors with the 3D visuals that the stereo testing requires. Proper alignment of the glasses with the corrective lenses allows for optimal visual clarity and accuracy in assessing the individual's stereopsis, or depth perception capabilities.