How Do Eye Tests Actually Work? Expert’s Revelation Goes Viral

An eye doctor has addressed a common source of confusion during routine eye exams, explaining how the process works in a now viral video.
Dr. Claudine Courey, also known as Dr. C or @eyedropshop online, shared insights into what optometrists are assessing when patients are asked to choose between lenses. Her video has garnered 16,000 likes and 497,900 views on TikTok.
“In the video, I address a common concern patients have during an eye exam—when they’re asked to compare lens options and they start to look very similar.
“Many people worry that they might be giving the ‘wrong’ answer but, in reality, when the choices between ‘one or two’ appear nearly identical, it’s actually a good sign. It means that we’ve fine-tuned their prescription very closely to their optimal vision correction,” Dr. Courey told Newsweek.

@eyedropshop/@eyedropshop
How Does The Test Work?
According to Dr. Courey, the goal of a refraction test is to achieve the sharpest and most comfortable vision correction possible. As the prescription is refined, the differences between lens options become smaller. When the choices appear nearly identical, it’s a sign that the prescription is close to being perfect.
The process, called subjective refraction, involves the patient comparing lens options while their eye’s focusing system and brain interpret the clarity of each one.
Dr. Courey explained that this method ensures the prescription is precise while accounting for individual differences in how people perceive sharpness.
Ultimately, patients shouldn’t worry about giving a “wrong” answer. Dr. Courey reassures them that when the lens options seem similar, it is a positive indication that their optimal vision correction is being achieved.
Why Are Eye Exams About More Than Just Glasses?
Dr. Courey emphasized that eye exams are about much more than checking if someone needs glasses—they are an important tool for assessing overall health.
“The eyes are actually the only place in the body where we can see blood vessels and nerves directly, which gives us an incredible opportunity to detect early signs of systemic health issues that people might not even be aware of yet,” she said.
For example, a close examination of the retina can reveal early signs of diabetes or high blood pressure.
A visual field test can help detect problems like brain tumors, strokes or eye conditions by showing where vision might be missing, which can reveal issues with the brain or the nerves that control sight.
Dr. Courey added, “It’s really incredible to think that a simple eye exam could potentially save people’s lives.”
Three Tips to Care for Your Eyes
Caring for your eyes doesn’t have to be complicated, says Dr. Courey. She offers three simple but effective tips:
- Follow the 20-20-20 rule: For every 20 minutes of screen time, take a 20-second break and look at something 20 feet away. This reduces eye strain and dryness.
- Wear sunglasses that block 100% of UVA and UVB rays to protect your eyes from harmful UV exposure, even on cloudy days.
- Get regular eye exams. Many serious eye conditions, like glaucoma or diabetic eye disease, develop silently without symptoms. Routine check-ups ensure early detection and prevention.
TikTokers Share Their Experiences
The video sparked discussions among TikTok users, many of whom have shared their own experiences with optometrists.
“My optometrist always says ‘one or two or are they the same?’ which is helpful,” commented one user.
“Why has no doctor ever said that to me?” asked another, Jennifer.
“People need to know they’re not trying to ‘win’ the eye exam. If you have to squint and guess at a letter, no, you can’t read it. Don’t guess. I didn’t know that till my 30s,” shared one viewer.
Another added, “I always feel like I’m failing some sort of test if I can’t see all the letters in the chart.”
“You can’t fail, I promise,” Dr. Courey reassured in response.
link