What do the numbers 50-18-140 in a frame marking stand for?

• A. first number eyesize, second DBL/bridge width, third temple length
• B. first number temple length, second eyesize, third DBL
• C. first number DBL/bridge width, second eyesize, third temple length
• D. first number frame height, second DBL, third lens diameter

Answer: (A)

These markings follow a standard eye size–DBL–temple length order. The first number is the horizontal width of one lens (eye size) in millimeters, the second is the bridge width (DBL) in millimeters, and the third is the temple length in millimeters. So 50-18-140 means a lens width of 50 mm, a 18 mm bridge, and a 140 mm temple length. This is why that option is correct. The other interpretations would place temple length or DBL in the wrong position, or refer to measurements not used in this three-number frame marking.