Or better yet, why not an F or another letter? Why E?
Well, blame it on Herman Snellen.
In 1862, Snellen put the E letter on top of an eye chart.
There were two eye charts that this Dutch professor of ophthalmology had made. The first chart had an A on top of it and the next chart was with E.
But Why an E on Top of an Eye Chart?
The letter E has three horizontal limbs. Each limb is separated by equal amount of a white space.
In the original chart, where it was headed by an A, the ratio between the height and width of all letters in the chart was 1:1. The gaps and bars were also of the same length.
Unlike other open letters, the E forces the examinee to distinguish between a white and a black, which is an important factor of a good vision.
If you don’t have a good vision, you can’t distinguish between white and black. That said, the E will begin to look like Ps, Fs, Bs and other letters.
But Snellen couldn’t just make the eye chart full of Es, else all of us would have a 20-10 vision.
However, the professor realized that using the same letters many times could ensure that the reason the patient’s failure to identify a letter was that of a visual problem.
The Modern Eye Chart
Some modern eye carts no longer start with an E. There’s no technical reason they have to be that way.
However, most charts still do use the E on top.
Despite the changes, it’s still a nice thing to know that even if we don’t see some letters below, we’ll always get the top letter right.
To help you get all the letters of the eye chart right, from top to bottom, from left to right, you should take a good care of your eyes.
Protecting your eyes should always start with the nutrients you’re taking. You must eat foods that are rich in lutein, vitamins C and E and omega-3 fatty acids. If you can’t take these nutrients, you may consider getting a supplement that can offer you the lutein that you need to protect your vision.