In March 2019, a social media post took many people, including eye care professionals, by surprise. The post compared two images of traffic lights and explained that people who see traffic lights as streaky or blurred likely suffered from astigmatism — the internet went wild.

While many eye doctors took to their keyboards to debunk the myth, it raised questions among everyday people with astigmatism and how it affects the way they view light. After all, astigmatism affects one in three people, so it can only benefit us to know how it affects us.

Below, we address astigmatism, how it affects one’s view of light and how it can make night driving particularly risky. Plus, treatment options to get you safely back on the road at night.

Astigmatism and lights

People with astigmatism may find themselves squinting to focus or reduce the glare they perceive from light sources. While this may seem ‘normal’ to those who have had astigmatism from an early age, those who have developed astigmatism often wonder why lights appear this way. 

To understand why astigmatism messes with the eyes’ light intake, you must first get a handle on what astigmatism is.

In a nutshell, astigmatism is caused by a misshapen cornea or lens, which makes it difficult for the eye to focus light. The cornea and lens are meant to filter outside light into the eye and direct it to the retina. The retina creates an image based on the amount of light received, then sends it to the brain (via the optic nerve) to make sense of the image.

In an eye with normal vision, the cornea and lens are perfectly round, like a golf ball. This allows light to hit the retina with no issues and produce a clear image. With astigmatism, either the cornea (called corneal astigmatism) or the lens (called lenticular astigmatism) are more curved than round — similar to an American football or an egg — which causes the light to scatter instead of focus on the retina.

Because of this, astigmatism lights will appear fuzzy with halos, streaks or glares