A Twitter post illustrating how people with astigmatism see light has gone viral and is causing users to question whether they might also suffer from the common eye condition.
The tweet, by Unusual Facts, depicted two side-by-side images of traffic at night to highlight the difference in vision between those with astigmatism and those without it.
In the ‘normal’ version, the traffic and rear lights had a slight blur around them.
But by contrast, the image representing what people with astigmatism see, showed streaks of light shooting out across the picture.
Since sharing the post has clocked up over 23K retweets and been liked almost 55K times.
The post also sparked a debate from people about which of the two images best represented their own vision and caused them to question whether they had an astigmatism.
So what exactly is astigmatism?
“Astigmatism occurs when one or both refractive surfaces of the eye do not follow a symmetrical curve,” explains Optegra optometrist Sundeep Vaswani.
“These surfaces include the cornea (front surface of the eye) or lens (inside the eye). Instead of being spherically curved (like a football), these surfaces are shaped more like a rugby ball. This can lead to distorted vision, blurred vision at distance and near, as well as night vision disturbances.”
Vaswani says many people are born with astigmatism, especially if there is a family history.
“Astigmatism can also develop over time,” he adds.
According to the NHS the exact cause of astigmatism is usually unknown although genetics can play a part.
“Sometimes astigmatism can develop after an eye injury, surgery or because of an eye disease. Astigmatism is not caused by reading in bad light, using a computer or watching too much television,” the site reads.
Elizabeth Hawkes, consultant ophthalmic and oculoplastic surgeon at the Cadogan Clinic, says it is the change in eye shape in astigmatism that could explain the illustration of the vision in one of the images.
“Due to the change in eye shape in astigmatism, the light entering the eye can result in blurred vision because there is a different strength of refraction in different meridians,” she explains.
Though the now viral images might help to highlight a potential astigmatism, Vaswani says it is best to get a proper diagnosis from an expert.
“Optometrists are well placed to be able to diagnose astigmatism, along with other refractive errors such as short-sightedness (myopia) or long-sightedness (hyperopia).
“Children are advised to have yearly eye exams with their optometrist and for adults, it should be every 1-2 years,” he adds.
According to Miss Hawkes anyone who suspects they have astigmatism should visit an optician or specialist eye clinic.
“Here we can diagnose the amount of astigmatism using corneal topography which maps out the curvature of the cornea. This is a very precise technique and helps us to plan our treatments,” she said.
How is astigmatism treated?
“Astigmatism can generally be corrected well with spectacles and contact lenses,” explains Vaswani.
“However, in higher levels of astigmatism, or where the cornea is very irregular, maximum visual potential may not be achievable with either option and specialised contact lenses may be required, or as an alternative vision correction surgery.
“These days there are various surgical options such as laser vision correction or refractive lens exchange,” he continues.
“These types of treatments can correct very high levels of refractive errors, including astigmatism and can offer many a permanent solution to glasses or contact lenses.”