Is this the end of the eye chart?
When it comes to testing vision, sometimes the best method is still the most basic.
By Megan Johnson
We expect to see certain familiar objects in a pediatrician’s office. There’s the stethoscope, casually draped around the doctor’s neck. The jar of tongue depressors. The reflex hammer, ready to whack a knee with its rubber triangle. And the slightly weathered eye chart, taped to the wall, its edges curling from years in the same place.
But these days, you’re likely to find a vision-testing contraption known as an autorefractor alongside those other objects. And this little machine, the size of a kitchen blender, could be a catalyst for ripping that eye chart off the wall — maybe someday relegating it to a kitschy antique or a source of a viral video, like the one where two teenagers attempt to use a rotary phone.
The need for vision tests is growing, because we’re using our eyes for functions that evolution never anticipated. The act of holding phones close to our eyes represents a huge change from hunter-gatherer days, when looking at faraway objects was a survival skill.
Today, the Centers for Disease Control and Prevention (CDC) reports that an estimated 61 million adults in the United States are at high risk for serious vision loss, though only half visited an eye doctor in the past 12 months. Children, meanwhile, are twice as likely to be shortsighted compared to 50 years ago.
“Nowadays, you have children in school using iPhones, iPads, and computers,” says optometrist Steven Lee, founder and chief science officer of Visibly, a Chicago-based company that creates digital eye care technologies. “Their eyes are adapting to become more and more nearsighted.”
And technology in the doctor’s office is changing, too. We’re indeed at the forefront of a revolution in the eye exam — but the classic eye chart will still have a role to play.
In ancient times, people often used the Big Dipper to test eyesight: If you could detect the optical double star at the bend in the Big Dipper’s handle, your vision was OK.
“There were all sorts of methods: using sticks, using lines on top of walls, whether someone could distinguish between two characters,” Lee says.
Today, the holy grail of eye testing is the Snellen eye chart, named for its 1862 inventor, Dutch ophthalmologist Herman Snellen. That’s the traditional 11-line chart you’re used to seeing in doctor’s offices, where 10 letters grow increasingly smaller as you move toward the bottom.
The original Snellen eye chart has entered the realm of kitsch. Cruise the internet, and you’ll find hosiery, flasks, flip flops, and shower curtains adorned with the same “E-F-P-T-O-Z.”
“With the Snellen, each character was created and designated because it allows someone to really accurately determine their level of acuity,” says Lee. However, the original Snellen has limitations, especially for patients who can’t name the letters — young children, people who can’t read, those who speak languages the doctor doesn’t understand, and those whose language doesn’t use the Latin alphabet.
That’s where newer charts came into play, such as the “Tumbling E,” a Snellen-like chart invented in 1976, and the “Landolt C.” Each chart contains only one letter and asks the test-taker to identify whether that letter is pointing right, left, up or down.
“It becomes super-easy for kids, where they can point in the direction the E is facing,” says Lee. Likewise, adults who don’t use the Latin alphabet can still indicate which way the E or C is oriented.
But the eye chart is only the beginning; today, sophisticated machines can determine your lens prescription. The autorefractor measures how light is affected as it reflects through the eyeball, while the photoscreener uses a camera to take images of un-dilated eyes. Both have popped up in pediatricians’ offices in the last several years to screen for kids who need a full eye exam.
The process can feel like magic: Patients place their face and eyes right up to the machine, which can perform a measurement and estimate a prescription within two or three seconds. If patients have no complaints about poor vision and get normal results on the autorefractor, they have passed the screening. But if the estimate doesn’t result in clear and comfortable vision, doctors will then use a phoropter, the classic, large testing device that looks like a pile of gears and switches between two lenses while patients read the Snellen chart to optimize the prescription.
Experts say the autorefractor and photoscreener won’t replace the traditional eye chart anytime soon.
“The eye chart would still need to be used to test how well a person saw, even after an autorefractor,” says Lee. “Autorefractors are only one part of the whole equation, and they only provide a starting point.”
And many doctors still prefer screening with an eye chart, since some children balk at putting their heads into clunky devices, says Mary Whitman, M.D., a pediatric ophthalmologist at Massachusetts Eye and Ear, a specialty hospital in Boston.
“In general, pediatricians are able to get better cooperation with the photoscreener,” said Whitman. Though some four-year-olds know their letters, Whitman says for younger children, she often uses the LEA chart, which gained popularity in the U.S. in the 1990s as a vision screening for children who can’t identify the letters of the alphabet. Instead of letters, it uses symbols like a square or a house. Another popular choice is the HOTV chart, which includes only those four letters.
Already, the original Snellen eye chart has entered the realm of kitsch. Cruise the internet, and you’ll find hosiery, flasks, flip flops, and shower curtains adorned with the same “E-F-P-T-O-Z” in decreasing size that you once found on the wall in your optometrist’s office.
Someday, patients may not even need to trek into an eye doctor’s office at all. Companies like Visibly, previously known as Opternative, provide digital eye exams online. Visibly’s five-minute test asks users to stand 10 feet from their screens and choose the symbols they see on their computer from a series provided on their smartphone. The company forwards a patient’s results to an ophthalmologist or optometrist, who reviews the results and provides a new prescription within 24 hours.
It’s a sign of the times that what used to require a trip into the doctor’s office now only requires a computer, a smartphone, and a $35 fee.
“I’m not a mind-reader, but I do believe that technology is going to play a huge role in terms of triaging patients,” says Lee. “In five to 10 years, most individuals will have a triage done online, and then only go into an office if necessary.”
Maybe then, the eye chart, like the rotary phone, will be phased into extinction, and we’ll see YouTube videos of teenagers laughing as they attempt to figure out how to use it.
Megan Johnson is a writer based in Boston.
Originally published at expmag.com on August 7, 2019.