A-A-53031 1987 Edition, June 29, 1987
PRISM BAR, OPHTHALMIC
Includes all amendments and changes through Cancellation Notice 1, September 11, 2012
Additional Comments: CNCL NO S/S
The General Services Administration has authorized the use of this commercial item description.
This Commercial Item Description covers two types of Berens prism bars:
Type I - Vertical Image Displacement Type II - Horizontal Image Displacement
The prism bars are to be used for vision screen tests to measure heterophoria or heterotropia in prism diopters and for converging and diverging exercises.