used to securely hold two Berens Prism bars side by side to get a quick estimation of a patient's yoked prism prescription or to evaluate the subject's fusional vergence system - in aluminum - 220gr - this item is sold individually (just the holder)

Accurately measuring the degree of strabismus using prisms is critically important when considering strabismus correction - less than ideal results in strabismus surgery may be due in part to errors in measuring deviations.

Large deviations are best measured by dividing the prism power between the two eyes, holding each of the two prisms in the frontal plane but holding two prisms in front of the eyes requires considerable dexterity. With Berens bars mounted both Base In or Base Out it is very easy to hold the prisms with one hand while keeping them correctly spaced - the holder allows simultaneous positioning of the prisms in front of each eye and can also be used on patients wearing glasses