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Yoked Prisms & Your Visual System


In other words, THERE IS MORE TO VISION THAN MEETS THE EYE! You must be able to accurately interpret what you see and experience to succeed.

Typically, spectacle lenses are used to alter the pathway of light in order to make the light focus on the fovea (the pinpoint of sharpest sight) on the retina (the back of the eye). There is an area of the retina in a bull’s eye configuration 10-30 degrees from the fovea and this is where the yoked prism optics enhances input. A prism deflects or shifts light but has no ability to focus light. Yet, the yoked prisms can change the phase or timing of light. Through this change in phase it can influence the communication between the visual, auditory, vestibular and proprioceptive sensory systems in the brain stem.


The brain stem contains the origins of the 3 cranial nerves that control eye movement as well as a number of non-sight vision connections.

Auditory (hearing)

The Auditory System helps organize transmission signals on all encoding processes. An example of Vision with Auditory is when some people say, “I can hear you better with my glasses on”.

Vestibular (inner ear balance)

The Vestibular System controls the stable posturing of the eye in the head. An example of Visual/Vestibular mismatch is when someone gets car sick riding in the back seat but not in the front seat. Another classic example is someone who mentions that when reading the words appear to “move” or “wiggle”.

Tactile/Proprioceptive (touch/stimuli of sensory nerve endings and muscle, tendons and joints that provide a sense of the body’s position.)

The Proprioceptive System (muscle tone) gives the elasticity to the eye alignment muscles and has recently been found to initiate short term memory. An example of Visual/Tactile-Proprioceptive is a person misjudging the height of a curb and missing a step.

A yoked prism spectacle prescription helps synchronize communication to allow more efficient and accurate information processing. A variation of prism design known as binary optics that also change the phase of light have been used in nautical lighthouses, holographs, spectrophotometers and its optical principles provide for the clear picture on a flat screen TV.

YOKED PRISM OPTICS are not needed or beneficial for everyone. Applications where yoked prism optics is often useful include:

  • Motion sickness/tight neck muscles.
  • Strabismus (eye deviation).
  • Vestibular disorders/nystagmus (a rapid involuntary moving of the eyeballs back and forth).
  • Ptosis (a drooping of the upper eyelid).
  • Vision related learning disabilities.
  • Adaptation of progressive lenses.
  • Head trauma patient.

The Yoked Prism Optics picks up where a standard lens can’t work. Areas that are affected include:

  • Improved eye tracking.
  • Increased accurate transmission to visual part of the brain used in learning (temporal and parietal lobes).
  • Quicker response time in sports.
  • Better and more comfortable eye movements when using computers.

Testing for yoked prism optics application: Dr. Wylie will make some specific measurements during the visual examination. If there is an indication for a prism prescription, the patient is rescheduled for further testing with a vision therapist to evaluate the visual system’s interaction with the other sensory systems and to determine if yoked prism lenses are right for you. The lenses are only prescribed if there is an immediate, consistent improvement in performance observable by the patient, parent (if applicable) and vision therapist. In the office we call it a “WOW” !!!


If the prism optics is incorporated with a patient’s habitual prescription – wear the glasses as usual. If the prism prescription is for reading and schoolwork – wear the glasses full time in the classroom and for all reading, computer, or homework done at home. If the patient is comfortable wearing the glasses they certainly can be worn for more situations than those described above, however, in most cases, they do not need to be worn during sports.


No! Our brains only need a 2% change in input to initiate a change in response. The prism amounts are small and the glasses look completely normal. The prism prescription can be added to any nearsighted, farsighted, astigmatism or reading prescription.


The wonderful news is, “NO”! The yoked prisms are a therapeutic prescription and every time they are worn the brain is undergoing training. Usually sometime between 12 and 24 months the patient finds that they are able to read and perform at their higher level just as well without the prism prescription. A reassessment with Dr. Wylie and a Vision Therapist can determine if the prism is still beneficial. This is example of the benefits of a Visagraph. We can record via infra-red goggles a patients eye movements and their eye movement efficiency is compared to norms of over 12,000 students.

In summary, a yoked prism optics spectacle prescription helps synchronize brain communication to allow more efficient and accurate information processing.

Please do not hesitate to call our office (509) 535-5855 if you have any questions or if you would like to schedule an appointment.