VT Works

In response to my recent series of posts detailing Wachs Mental Minus, a fellow Vision Therapist reached out asking about the Bifocal Rock (aka – Split Pupil Rock) activity. Although not technically a part of the Wachs Mental Minus series, it tends to fit nicely as an adjunct and is certainly a nice tool to have at one’s disposal when working on accommodation.

In terms of how the activity is done, here is my explanation to the best of my understanding:

The setup is a bit different than most of the Wachs Mental Minus series in that this activity is mostly done while the patient is standing, while wearing a translucent eye patch covering one eye, and viewing a Marsden Ball hanging 6-8 feet in front of them. The patient will need a monocular lens, which for this activity, the higher powers tend to be more demonstrative, so my starting point is generally a -5.00 or higher. We will eventually move into lower powers, increasing the demands of their Just Noticeable Difference awareness.

Before we start with the lens, I’ve found it’s a good idea to have a conversation about the space that exists between the patient and the Marsden Ball. Some patients like to identify the number of feet they are away from the ball, some imagine the percentage of the room occupied by said space, and some have even counted floor tiles as a means for quanitifing the space; whichever, method the patient is comfortable with works, as the idea is simply for them to have an appreciation for the quality and quantity of the space before introduing the lens. Since this activity tends to combine the “Where Am I?”, the “Where Is It?”, and the “What Is It?”, calling the patient’s awareness to these areas as a primer seems to help them find success.

As the patient raises the lens to a full arm’s reach, they should observe two targets; the actual ball hanging in the distance, and the image created by the lens. Once we establish the patient is able to observe the two targets simultaneously, it’s important to take a very Socratic approach, meaning we ask a lot of questions and offer very little that may influence the patient’s experience.

My first question (with most activities) is easy: “What do you see?”

From there, some suggested questions might be:

• Are you able to make each image clear on command?
• What happens to the other ball when you are NOT looking at it?
• How are the two images the same?
• How are the two images the same?
• How are the two images not the same?
• How do your eyes feel when looking at the ball inside the lens?
• How do your eyes feel when looking at the ball outside the lens?
• Does anything change if we make the ball move? (if you decided to swing the ball, I have found the most success in swinging along the Z-axis and only a few inches of arc)
• Where would you estimate the big ball to be?
• Where would you estimate the small ball to be?

The idea of this procedure is to challenge the accommodative system by asking them to quickly change their focus from the lens to the ball, while asking the patient to demostrate their appreciation of the SILO aspects of the lens. This is why starting with a higher powered lens tends to work better as there will be more disparity between what they view in the lens and real space.

A lot of patients seem to struggle with the SILO appreciation aspect of this activity, perhaps due to their “logical brain” taking over, and so they report the small image inside the lens to be the further target. If we have patients who demonstrate this, it becomes important to ask questions that draw out the awareness of the smaller image being created by the lens, without which, there would be only one ball. If you can do this, my experience has been that many patients will engage their visual brain and seek the information which confirms the smaller ball is, in fact, closer.

Other strategies to try are having the patient wiggle the lens a little (remember, movement helps with the “Where Is It?”) as well as changing their space by having them walk a bit closer to, and farther from, the ball while looking through the lens. As the patient progresses, we can offer them less powerful lenses to see if they are able to appreciate the same awarenesses.

Where exactly this activity would fit in terms of your accommodative sequencing of Vision Therapy would seem to depend on a few different factors: one might be the patient’s skill level in the associated areas (accommodation, vergence, spatial awareness, body awareness, to name a few), and the other would be the determination of the Developmental Optometrist based on the results of the patient’s exam and current level of progress. Because this activity tends to require an increased level of awareness and skill, it’s important it is done at a point in a patient’s program when success is attainable.

The last key of this activity to mention is the importance of patient discovery, rather than offering the patient “the answer”. As a Vision Therapist, it’s important that we do not offer “our view” on the activity nor should we be offering the patient what we know the answer “should be”; instead, as with most activities, we want to find questions which encourage a lot of visual self discovery in order for the patient to make noticeable, functional, and sustainable visual changes.

Cheers!