Used to measure Afferent Pupillary Defects (APD) which is defined as diminished pupil reaction to light levels. It uses 6 standard ND levels for quantifying APD. The log units quantify the amount of light transmitted through the filter. Includes 6 filters rated as 0.3, 0.6, 0.9, 1.2, 1.5, and 1.8 log unit optical density values. The 0.3 ND filter is most useful for uncovering a borderline pupil defect.

The filter bar can be used in conjunction with the “Swinging Flashlight” test to detect and quantify the depth of any afferent conduction defect.

Fits in shirt pockets. Includes leather slipcover. Overall bar is 6.5" x 1" (16.5cm long and 3 cm wide). Each filter measures 7/8" by 1" (2.5cm x 3 cm).