I have been wearing glasses since I was 14, which means that this year marks exactly 20 years since I got my first pair. In the beginning, I had to wear them all the time, but as the years passed, my eyesight changed and eventually I only needed my glasses for reading. This continued for a long time. I never really noticed any major change in my vision, so I slowly stopped taking my annual eye examinations seriously. In fact, three years passed without a proper eye test. Then I finally went for one – and the result was quite a surprise. My distance vision had become significantly worse during those three years, even though I had hardly noticed it in everyday life. So, after many years of wearing glasses mainly for reading, they are going to become part of my daily life again.

Fortunately, I have never really had a problem with wearing glasses. My first pair had a semi-rimless frame, which was extremely fashionable in the mid-2000s. Later, I started experimenting with full-rim frames as well. And this is perhaps the positive side of needing glasses: they do not have to be only a medical device. A good pair of glasses can also be an accessory. The right frame can change the way your face looks, match your clothes and even give you a little extra character.

Still, my recent experience taught me something important: we may not always notice that our eyesight is getting worse.

Our eyes can change slowly

One of the reasons people put off eye examinations is very simple: they think they can still see well enough.

That was exactly my case.

The problem is that changes in vision can happen gradually. If something becomes a little more blurred every month, your brain can partly get used to the change. You may simply start sitting closer to a screen, squinting at distant signs or moving things nearer or farther away without really thinking about it.

According to the National Eye Institute, some people with refractive errors do not realise that they could be seeing more clearly. Blurred vision is the most common symptom, but eye strain, headaches, squinting and difficulty focusing can also be signs that your prescription has changed.

This is one of the biggest reasons regular eye examinations are useful. You do not have to wait until you suddenly think, “I can’t see properly anymore.” An eye test can discover smaller changes before they become obvious in everyday life.

An eye test is about more than choosing new glasses

When most of us think about an eye examination, we probably imagine reading letters from a chart and answering the famous question: “Is it clearer with number one or number two?”

But a proper eye examination can do much more than tell you what strength of glasses you need.

Eye-care professionals can also look for signs of eye diseases and other problems. Some eye conditions develop with few or no noticeable symptoms in their early stages. The US Centers for Disease Control and Prevention explains that comprehensive eye examinations can help detect eye diseases early, when treatment may be more effective. An examination can sometimes also reveal signs connected with other health conditions, such as diabetes or high blood pressure.

Glaucoma is a good example of why this matters. It damages the optic nerve and often causes no symptoms at first. Vision may disappear so gradually that a person does not realise something is wrong. The National Eye Institute says that a comprehensive dilated eye examination is the way to detect glaucoma, and early treatment can help protect vision.

In other words, an eye examination is not simply about getting stronger or weaker lenses. It is also a health check for two extremely important parts of your body.

“But I can see perfectly well…”

That sentence is probably responsible for quite a few missed appointments.

We often go to a doctor because something hurts. Eyes are different. As the NHS points out, our eyes rarely hurt when something is wrong with them. This is why regular checks are important even when everything seems normal.

And sometimes the difference becomes obvious only when the optometrist puts the correct lenses in front of your eyes.

Suddenly, the letters become sharper. Details appear again. Things on the other side of the room look clearer than you remembered. At that moment, you may realise that what you thought was “normal vision” was simply something you had slowly become used to.

That was probably the most surprising part of my own experience.

How often should we have our eyes tested?

There is no single schedule that is perfect for every person. Recommendations also differ between health organisations. The American Optometric Association recommends annual comprehensive eye examinations for adults as a proactive approach, while the NHS generally recommends a sight test every two years, or more often when an optometrist advises it. People with certain medical conditions or a higher risk of eye disease may need examinations more frequently.

So an annual eye examination is a particularly useful habit for people whose vision is changing, who already wear glasses or contact lenses, or whose eye-care professional recommends yearly checks.

And, as I have now learned, three years can be quite a long time.

One appointment can make a big difference

It is very easy to postpone an eye examination. We are busy. We can still read the computer screen. We can still recognise people across the room. We tell ourselves that we will make an appointment next month – and suddenly several years have passed.

But our eyesight is something we use from the moment we wake up until the moment we close our eyes at night.

Regular eye examinations give us the chance to notice changes that we may not recognise ourselves. They can make sure our glasses still have the correct prescription, check the health of our eyes and sometimes discover problems before they begin to affect everyday life.

My own three-year break from eye tests ended with a new prescription and the news that glasses will once again become a permanent part of my everyday appearance.

And actually, I am quite fine with that.

After all, if I am going to see the world more clearly, I might as well choose a frame that looks good while I am doing it.