Legal blindness is a term used to establish eligibility for Social Security and other benefits. The next largest letters on most eye charts (2200) is the usual standard. These letters are 10 times larger than 20/20; this refers to best corrected vision only. No permanent damage is done to adults who wear an incorrect eyeglass or contact lens prescription. You may, however, be uncomfortable wearing them and annoyed by the inconvenience. Return to the optician to see if the lab made them correctly and that they are adjusted properly to fit your eyes and face. Changing the base curve, bifocal type, height or pupillary distance also are sources of dissatisfaction even when the prescription is correct. If all of these are OK, then return to the ophthalmologist who prescribed them to see if there is a different option for you.