Check the listing for details. Ishihara Test Book 24 Plate With Occluder For Color Deficiency. Condition: New, Made in India. Listed at 37.78 USD. Ishihara Test Chart Books for Color Deficiency Plates Edition With Manual & Occludar. Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those with a red-green color vision defect, or the other way around.