Related Experiment Video
Updated: Aug 9, 2026

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients
Published on: March 29, 2022
Effect of prescribed prism on monocular interpupillary distances and fitting heights for progressive add lenses
1School of Optometry, Indiana University, Bloomington.
Abstract:
Success in fitting progressive addition lenses is dependent upon the accurate placement of the progressive zone. Both eyes must track simultaneously within the boundary of the progressive corridor. Vertical prism will displace the wearer's lines of sight and consequently eye position. Because fitting heights are measured using an empty frame, subjects with vertical phorias usually will fuse, and not show the vertical differences in pupil heights during the measuring process. Therefore, when prescriptions contain vertical prism one must consider the changes in measured fitting heights that will occur once the lenses are placed in the frame. Fitting heights must be altered approximately 0.3 mm for each vertical prism diopter prescribed. The fitting height adjustment is opposite from the base direction of the prescribed prism. An explanation of the effect of prescribed horizontal prism on monocular interpupillary distance (PD) measurements is also included.
Related Concept Videos
Glaucoma: Overview
Open Angle Glaucoma: Treatment
Drugs such as carbonic anhydrase inhibitors, α2- and...
Focusing of Light in the Eye
Depth Perception and Spatial Vision
Influence of Earth's Curvature and Atmospheric Refraction on Leveling

