Eyes: People realize that they have astigmatism after this photo has become viral

A Twitter article illustrating how astigmatas see light became viral and prompted thousands of social media users to realize that they themselves suffered from eye disease.

Unusual Facts' tweet of March 25 described two car shots taken in traffic at night on a highway, their red taillights lighting up, but not the other.

It has been retweeted 23,000 times and appreciated nearly 55,000 times at the time of writing, as people try to decide which of them best represents their own vision experience.

The image on the left illustrates what the astigmatism would see, which, as Unusual Facts suggests, is linked to a slightly curved cornea.

Astigmatism means that your eye has more the shape of a rugby ball than a football ball. The light is therefore focused at more than one place in the eye.

This can cause: blurred vision, headaches and eyestrain.

Essentially, the curves of the cornea on the anterior surface of the eye and lens inside are incompatible, which means that the incoming light rays do not refract as they would in the case of ## EQU1 ## 39, a perfect eye. Instead, the light hits the retina at several points, creating a fuzzy effect.

The condition is most often present combined with another refractive error such as myopia or long-term vision.

The reaction to the tweet on stray light was largely a surprise:

All of this is true, of course, and without cause for concern, although you should obviously visit an optician if you feel uncomfortable about your vision.