Herman Snellen, a Dutch ophthalmologist, introduced the now commonly known Snellen Eye Chart in 1862 to test visual acuity in clinical practices. The visual acuity tested through this chart is the clarity of a person’s eyesight from a distance. So a 20/20 vision does not mean that a person’s visual acuity is perfect. This chart mainly measures eye defects, namely Myopia, or nearsightedness, Hyperopia, also known as farsightedness, and Presbyopia. This test can also be done online by following the instructions on your screen or with the help of PDFs that come with the chart and instructions to test your vision.
There are other tests like the Snellen chart that also measure visual acuities, such as the Tumbling E test, Landolt C test, LEA symbols chart, and many others. This list of Snellen and the likes eye test apps are sorted by a study but are only available for iPhones.
For Android users, there is an array of visual acuity test apps on the PlayStore. The Visual Acuity Test uses tests such as Snellen, LogMAR chart, Tumbling E chart, and others to test visual acuity, astigmatism, and color blindness. The Eye Exam Pro also does these jobs but also uses symbols for children.
What is visual acuity?
Visual acuity is defined as the overall ability of the eye to perform various visual tasks it has been trained to accomplish. These visual skills range from the ability to focus on objects, depth perception, peripheral vision to color perception.
— bioRxiv (@biorxivpreprint) March 23, 2022
The visual acuity assessment exams that use scientific charts still are not authorized to provide a prescription. If you are looking to upgrade your glasses or already have a prescription but want to test your vision at home without having to physically go to an optician, then these online resources are not that bad. However, in case of eye defects, or diseases, that require medical attention, a visit to an ophthalmologist would be more beneficial.
Online eye exam assessment
For common eye defects, online testing is more sustainable for the current times. Going physically to optical stores and hospitals may not always be feasible. Therefore, the online tests do provide some comfort. The tests mainly measure the sharpness of the vision, astigmatism, light sensitivity, and color perception.
Astigmatism is a condition where the image of the object seems different than “normal” because the cornea is not perfectly rounded. In this case, the images seem blurry, and a person may not be able to see an object’s dimensions clearly. And it is also common to have Myopia or Hyperopia along with astigmatism.
So far, I only knew that I had mild Myopia, but one of the online tests revealed that I might have astigmatism. French company Essilor has a wide range of online tests on their website, and I took them all. It does not say much about my Myopia, but I still think that the test for astigmatism, and color blindness, were a huge relief to have at home.
The Japanese Ishihara test for color perception, published by Shinobu Ishihara in 1917, tests the perception of the red-green colors of the light. Individuals with this condition are not able to differentiate between red and green hues of light. The original test consisted of 38 Ishihara color plates, including ‘plate no. 1’ that lets a fully color blind person understand how the test works. Most modern-day tests include only a few plates because the lack of cones in the fovea of the eye is apparent quickly.
ZEISS, a German company well-known for its lenses, has an optical care division that also follows the same protocol as most other optical websites. I observed similar results here as well. And I do not have color perception issues.
Eye exam and AI
Rodenstock is a German optical company whose history can be traced back to 1877. Founder Josef Rodenstock along with his brother Michael, started “Optisches Institut G. Rodenstock” company in Würzburg. The company used to sell self-designed eye measurement instruments along with lenses and frames.
They announced their BIG (biometric intelligent glasses) vision in 2020. Staying true to its roots, the company has been toying with AI to find solutions to accurately measure the dimensions of the eye. With their BIG idea, they have created lenses and glasses that measure the biometry of the eye. The biometric data will be integrated into each new lens and modulated according to the wearer’s eye. This makes me wonder if they have gone too far in their quest to find technological solutions to help the sight.
— Rodenstock (@Rodenstock) July 7, 2020
Things to consider
Buying glasses online based on these tests is not advisable. However, you can buy glasses without vision correction to keep away from the glare produced by the screens. The dilation and constriction of the pupil, although an autonomous process of the brain, requires a lot of effort from all the eye muscles to cooperate and work as per the requirement of the brain. This process will never be flawless because the muscles get tired after a period of time. This is also one of the reasons that induce migraines and headaches while scrolling through or viewing something bright and colorful on a screen.
Sometimes, when I get migraines and need some screen entertainment, I turn the screens’ colors to black and white; although nothing is visible in B&W, it’s all pretty shades of grey. The following room has a 2% brightness being emitted from the smart bulb in the lamp, and the TV’s B&W brightness is 40%, while a gleaming 40W non-smart bulb lightens the corridor outside.
These tiny details about your vision health cannot be measured by online tests. But technology has come a long way for us to be able to modulate the source of our needs based on the consumption capacity of the brain. We have a natural tendency to find a patch of shade on a scorching sunny day, and the tech world today has been able to find its own unique shades of grey.