Definition of Legally Blind and 20/20

Definition of Legally Blind and 20/20
Dr. Phillip L. Carney, Jr.

Most everyone is familiar with the terms “20/20” and “legally blind”, but what do they really mean? 20/20 vision is the ability to see a letter or symbol correctly at 20 feet that has a certain degree of size.  Basically, this is the ability to see a small letter at 20 feet with the best possible correction.  Most normal eyes should be correctible to 20/20.  Some can see even better at 20/15 or even 20/10, but most consider 20/20 to be perfect.  In contrast, having 20/200 vision means that the letter would have to be 10 times larger to see at the same distance.

There is a very important distinction between corrected vision and uncorrected vision.  Legal blindness, by definition, is with corrected vision.  In other words, with the best possible correction either by eye glasses or contact lenses, anyone who has worse than 20/200 vision is considered legally blind.  Very few people fall into this category, as those with very poor vision should be correctable to 20/20 with glasses or contacts.  Those who are legally blind may benefit from contacts or glasses, but still have great difficulty seeing, even with the best correction.

Dr. Carney is available for all your eye care needs by appointment at Welch/Wallace Laser Center by calling (318) 448-0221.