How can one have a visual acuity above 100%?? | Source: © Roman Samborskyi / Shutterstock.com
More than 100% is not possible – you would think so. That’s why not only mathematicians regularly look in disbelief at the results of their eye test, which certify that they have a visual acuity of 125 % and more. How is this possible? Is there something wrong with our eyes if we have more than 100% visual acuity? Can we see more than others? Seeing through things?
No, of course not. 100 % visual acuity and more are not so rare at all. Many young people with healthy eyes even crack the 200% mark and still have no exceptional abilities.
The reason for visual acuity values of 100% and more is a mixture of convenience and mathematics. Actually, visual acuity, which is also referred to medically as "visual acuity", is indicated with a decimal number. This number usually ranges between 0.1 and 2.0. A visual acuity of 1.0 is a visual performance that the "average person" achieves. Young children under 5 and adults over 70 often have visual acuity below 1.0. Young adults from 18 to 30 often manage a visual acuity of 1.6 to 2.0.
However, because the decimal number 1.0 is difficult to communicate with patients and customers, ophthalmologists and opticians have simply made percentages out of it. A visual acuity of 1.0 has become a visual acuity of 100. A visually impaired person with a visual acuity of 0.05 has a visual acuity of 5%. For a young person with a visual acuity of 2.0, this logic then results in a visual acuity of 200.
What does 100% visual acuity actually mean??
Put simply, visual acuity, sometimes referred to as visual power or visual performance, is a measure of the resolving power of our eyes. It is comparable to the pixel count of a camera. The higher the resolution, the sharper the image. The calculation of the resolution is pure mathematics and has to do with minutes of angle – nothing that laymen have to deal with. For them, it is more exciting to know what 100% vision means for their daily lives.
Do I need 100% visual acuity for my driver’s license??
No. According to the law, 50% visual acuity (or: a visual acuity of 0.5) is sufficient to drive a car in Germany. Of course, this is not very good, but by this regulation it is achieved that only a few federal citizens are forbidden to drive a car. Nevertheless, there are many other reasons to be afraid of the driver’s license eye test.
Why am I recommended to wear glasses despite 100% visual acuity??
For certain activities it makes sense to wear glasses, even if 100% visual acuity is already achieved without a visual aid. For example, computer workstation glasses that increase resolution can significantly increase the effectiveness of work. When driving, a slight increase in visual acuity to 125% increases safety on the road.
Glasses are important for many young adults with farsightedness. They achieve good or very good visual acuity without glasses, but only because they constantly strain their eye muscles. Glasses do not increase the visual acuity of these people, but the well-being. With glasses you feel less stressed and much more relaxed. Or: Why do I not reach 100% visual acuity despite wearing glasses??
In the case of reduced visual acuity, a distinction is made between correctable and non-correctable causes. Correctable causes, such as simple nearsightedness or farsightedness, can be compensated for with glasses and contact lenses, so that you end up with 100% visual acuity or more again with the visual aid. However, there are also disease-related causes that result in you having far less than 100% vision. This can be astigmatism or clouding of the cornea, age-related macular degeneration, or optic nerve impairment. If correctable and non-correctable causes come together, you will not achieve 100% vision even with the best glasses.
Depending on the type of impairment, however, a combination of different visual aids can bring an improvement. For people with corneal injuries or irregular corneal curvature, it is possible to increase vision with special (medical) contact lenses that are worn in addition to glasses – perhaps not to 100% vision, but at least in such a way that the quality of life of those affected is noticeably improved.
At what point is the vision too low?
In Germany, a person is considered visually impaired if he or she has less than 30% vision. People who fall below this value often have the possibility to get co-payments from the health insurance for glasses and contact lenses.
Discover now more vision fairy tales and get to the bottom of vision myths. Or send us your own question now, easily via email or Facebook Messenger.
Find an optician near you now. Just enter your zip code or city and off you go!