This instrument has four sides that have different measurements or functions:
• One side features diopter measurements from 20 to 2
• One side features a ruler from 5 to 50 centimeters
• One side that tests ages 8 through 48
• One side that tests for convergence, normal, reduced, and defective
• One side features diopter measurements from 20 to 2
• One side features a ruler from 5 to 50 centimeters
• One side that tests ages 8 through 48
• One side that tests for convergence, normal, reduced, and defective
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