Its Medical Name Is an Optotype

This page is the CodyCross answer for the clue below from Mesopotamia, Group 968, Puzzle 4 (Proverbs and Sayings).

Question is: Its Medical Name Is an Optotype

and the answer is: EYECHART

Word Meaning:

EYE CHART — A sign or poster showing letters or symbols in progressively smaller lines of type, used to test the acuity of distance vision.

Definitions from Wiktionary.