The Bishop Dual Prism Alignment System is a new tool developed to provide advantages in measuring large-angle strabismus prior to correction. In strabismus, one eye looks directly at the object being viewed while the other eye is misaligned inward (esotropia), outward (exotropia), upward (hypertropia), or downward (hypotropia). When the misalignment of the eyes is large the strabismus is called "large-angle," referring to the angle of deviation between the line of sight of the straight eye and that of the misaligned eye. Accurately measuring the degree of strabismus using prisms is critically important when preparing for strabismus correction. With the Bishop Tool, two base-in or base-out prisms are held in place using magnetic fixation to a metal plate with a ferrous surface. The tool with the two prisms can be positioned using one hand, freeing the other hand for note-taking and/or cross-eye cover testing. The prisms can be placed base in, base out, spaced for the patient’s PD, and are held correctly in the horizontal and frontal planes by magnetic fixation to the plate. The Bishop Dual Prism Alignment set includes a red lens, 16 prisms in 0.5, 1, 2, 4, 6, 8, 10, 12, 15, 20, 25, 30, 35, 40, 45, 50 diopters with magnets mounted for use with the base plate. Note: These magnetic prisms are not recommended for use with a magnetic stick.
