Learn about Prism Lenses!
Lenses are an Optometrist’s most powerful tool. They have the ability to achieve an alteration of human behavior.
Prism lenses are lenses that change the direction of light rather than condense or expand light as conventional lenses do. They are typically used to enhance one’s ability to coordinate eyes in relation to the coordination of their bodies. Instability in visual and/or motor function typically warrants a prism correction lens. Vertical yoked prism prescription have the potential to reorder and reorient visual function by simultaneously affecting visual motor and visual sensory processes.
The term “yoked prism” was originally used to differentiate it from the typically prescribed lateral prism. They are defined as a pair of prism lenses of equal power with their prism base in the same direction. The utilization of these prism lenses are highly selective and specific. Low powers, ranging from 1/4 to 5 prism diopters are typically prescribed in and/or out of office use. Currently, we have the means to determine the direction of base, yet the degree of power is based on professional judgement. In the final analysis, the true value of a yoked prism is its influence on the patient’s orientation. Most often, a generalized behavioral effect is represented by a demonstrable improvement of spatial awareness and orientation.
Basic philosophy of Behavioral Optometry and the use of vertical prism prescription is that efficient aquisition and processing of visual information requires the development of a good representation of the 3-dimensional structure of body and environmental space and the ability to move attention freely within this space.
The clinical presentation of pediatric patients with significantly reduced awareness of space related to a lack of focus, inattention, distractability, hyperactivity, impulsivity, limited eye contact, excessive visual search, and/or perseverative mannerisms are typically difficult to treat. The “associated diagnosis’ may range from Autism and Pervasive Developmental Delay through Hyperactivity and can frequently involve Oculomotor Dysfunction. The central theme of a prism len correction is that visual disorders can significantly contribute to adaptive behavioral skews which are related to movement of the body in space.
A “VERTICAL YOKED PRISM” AFFECTS OUR ABILITY TO FUNCTION IN THREE WAYS:
Its initial affect is to raise or lower eye gaze. Dr. Warshowsky most often prescribes vertical yoked prism in the base up position, which serves to lower eye gaze. This promotes the ability to converge (turning inward) one’s eyes. The nature of our eyes is that upon downgaze eyes turn inward. In the same sense, up gaze promotes divergence (turning outward). Eye motor skills will begin to stabilize with base up vertical yoked prism correction.
Once convergence is stabilized, one’s ability to know where an object is in space in relation to oneself (egocentric process) is enhanced. Spatial judgement will begin to develop.
Ultimately, postural control will begin to develop from a counter balance shift in the center of gravity of the body as a result of an eye motor shift in gaze. As eye gaze shifts downward, a counter balance shift in the center of gravity of the body shifts in an upward and outward manner. The effect is as if one is moving backwards on the heels of their feet, creating a correction of one’s body posture. A child will begin to become less overly active in their behavior.
“YOKED PRISM CORRECTION” REPRESENTS A BEGINNING PLATFORM UPON WHICH CHILDREN CAN LEARN TO REBUILD A STABLE AND EFFICIENT VISUAL WORLD”.
Vertical yoked prism – Prism Lenses – Prism Glasses