PRISM IN STRABISMUS
Abstract: Prism is a transparent optical element with flat, polished surfaces that deviate entrance light beams, so all the applications of a prism result from this main feature. Prism consists of a vertex part and a base part. When the optical beam passes through the prism deviates toward the base, so this feature leads the image to move toward vertex. Prisms are used in visual sciences to build a variety of devices, including keratometers, ophthalmoscopes, slit lamps, applanation tonometers, etc. Also, using prism is considered one of the critical methods for solving the problems caused by uncompensated heterophoria, strabismus, nystagmus, vision field problems, etc. optometrists and ophthalmologists prescribe it all around the world. It should be noted that some of the uncompensated heterophoria symptoms, as well as strabismus ones, can be removed just by applying a prismatic effect, which can be considered by prescribing prism glasses, changing the spectacle pupillary distances, or both of these methods. There are a variety of criteria for prescribing a prism glass that some of the essential ones include Sheard, Percival, fixation disparity, and clinical wisdom criteria. Despite all these descriptions, Prism is not the first option of prescribing in all vergence dysfunctions, but prescribing it can be untying in many cases.
Aria Bouyeh1 *, Narges Jamshidian2