For example, the letter Q’s tail can be recognized because there are no other letters like it. The reason behind these letter choices is that some letters can be distinguished even with blurry vision. You may have noticed that the only letters used are C, D, E, F, L, N, O, P, T, and Z. The sizes of the letters are precisely calculated to adhere to the standard of the 20/20 scale. A Dutch ophthalmologist developed the chart in the 1800s. If you’ve seen an eye doctor, your visual acuity was tested using the “big letter poster” or Snellen chart. Visual acuity is also not the determining factor in your overall eye health. While visual acuity is a good measure of the sharpness and clarity of your vision, it does not take into consideration other fundamental aspects of vision. If someone has less than average vison, say 20/70, what they see at 20ft is what a person with perfect vision can see at 70ft. So if you have 20/20 vision, you can see at 20ft what someone with perfect vision can see at that distance. This number measures visual acuity, which is the clarity or sharpness of your vision measured at a distance of 20ft. That 20/20 number is a term used to represent normal or ‘perfect’ vision. But what does that exactly mean? And is it an accurate indicator of “perfect” vision? We have all either heard someone or ourselves brag that we have “20/20 vision”.

2020 vision meaning