detects subtle effects of defocus, low luminance and glare - each line is a lower contrast than the one before it, using Log CS steps Log CS increases 0.25 steps per row (0.05 log CS/letter) - this progression in contrasts helps to identify the patient's contrast sensitivity - 20/50 letter size at 4 meters (13 feet) - includes soft-tipped pointer, recording forms and test instructions - optional: glare filter, low photopic filter - to be used in the LED illuminated cabinet 50.028.00