Often, patients come into my practice for new spectacles with a sense of dread that their prescription may increase.

A patient said the other day that she is “sick of her prescription increasing”.

So let us discuss a few reasons why your prescription may increase, and why it is not always as simple as “my eyes are getting worse”.

Progressive Shortsightedness or Myopia

There is a pandemic across the world: progressive myopia, also known as shortsightedness.

When you are young, usually between the ages of 0 and 25 years, and you are shortsighted, your prescription may increase every year. This means your lenses may get thicker every year.

This is due to physiological changes within the eyeball itself. The eyeball keeps growing.

For years, eye care practitioners have been aware of this, but have had very limited ways to intervene. Many years have been spent on research to try to slow down this pandemic.

Luckily, these days we have intervention strategies such as DIMS lenses, which stand for Defocus Incorporated Multiple Segments. These are very specialised lenses, specifically designed and well researched to slow down the progression of myopia by decreasing the rate at which the eyeball grows.

The prescription may still increase, but at about a 60% slower rate.

There are other intervention strategies available, but DIMS lens technology is the intervention I use the most.

If you or your loved one is shortsighted and between the ages of 0 and 25, has your optometrist offered you specialised myopia control lenses?

Unfortunately, these lenses can be unaffordable for some. This is because of the intense amount of research that has gone into designing these lenses, and research has a massive cost to it.

Accommodative Dysfunction

The lens inside our eye can change focus and change power within the eye.

Think of a camera where you have to turn the dial every time you want to take a photo at different distances to get it into focus. The lens inside the eye works in a similar way.

Sometimes this focusing system can become dysfunctional.

Because of the massive amount of near work we do nowadays, especially on computers, phones, tablets and books, our accommodative system can go into a spasm. This can result in blurry vision at distance and can create something called pseudo-myopia.

Pseudo-myopia means that it may look like the patient is more shortsighted than they truly are, but the issue is actually linked to the focusing system.

Symptoms of Accommodative Dysfunction

Symptoms of accommodative dysfunction can include:

• Intermittent blurriness at near and at distance
• Near-to-far blur and far-to-near blur (Looking down at your book and then looking up into the distance, it is blurry for a second before it becomes clear, and vice versa)
• Headaches
• Fatigue
• Difficulty concentrating

That is why at our practice, we do a multitude of accommodative tests before we prescribe, to make sure we are not making the prescription stronger than it is supposed to be.

We treat the underlying cause through eye exercises and help mitigate the symptoms with specialised lenses called accommodative support lenses.

This is one of the reasons why a proper optometric examination should not just be about seeing clearly on the letter chart. Vision must also be comfortable and functional.

Eye Alignment and Binocular Vision

When we think of a squint, we usually think of someone having one eye looking in one direction and the other eye looking in another direction. That is very conspicuous.

However, someone’s eyes can be ever so slightly misaligned, and only a trained optometrist can detect it. Most often, this requires specialised testing.

When the eyes are misaligned, especially more outwards, the patient may want a stronger prescription because it activates accommodation. When accommodation is activated, the eyes converge, meaning they come together as a team.

This can temporarily make the eyes more aligned.

But again, with a prescription that is too strong, it can create accommodative dysfunction. This may result in the patient needing a stronger prescription the next time they visit the optometrist.

That is why at our practice, we do binocular vision tests. We check eye alignment and make sure the eyes work together as a team to ensure that your prescription will not be too strong.

Symptoms of Eye Misalignment

Symptoms of eye misalignment can include:

• Double vision, seeing two of the same thing
• Shadows around objects or words
• Blurry vision because it is linked to the accommodative system
• Headaches
• Eye strain, where the eyes feel like they are pulling or heavy
• Difficulty sustaining concentration on near tasks

To treat this, we may do eye exercises to help with the misalignment of the eyes. Sometimes, we may also add prism lenses to move the light to where the eye is.

This can improve comfort and symptoms, helping you function more optimally.

Presbyopia and Near Vision Changes

Presbyopia relates to near vision. It happens to everyone as we have more birthdays.

It usually starts at around age 42, when near objects become blurry, or reading becomes more difficult, even if you have never worn glasses before.

You may start pushing objects such as your phone further away in order to see clearly.

At one point, you cannot stretch your arm far enough anymore, and you will have to rely on reading spectacles, bifocals or multifocal spectacles in order to see clearly.

Every few years or so, you may notice that things become blurry again, and you will need to update your prescription.

This is natural. You will need a stronger and stronger prescription as you have more birthdays.

This is not because the glasses are making your eyes weak. This is due to natural physiological changes of the lens inside the eye, where your accommodative ability, or the flexibility of the lens inside the eye, reduces.

Can Presbyopia Be Slowed Down?

There is nothing to cure or slow down presbyopia.

There are some claims out there that certain treatments, eye exercises or herbal teas can slow down presbyopia. I am very sceptical about that, and you should be too.

As an optometrist who specialises in eye exercises, I do not know of eye exercises that will slow down presbyopia.

The only treatment for presbyopia is spectacle lenses. Multifocals are often the best option because they allow you to see at various distances all the time.

Multifocals can be expensive. The best multifocals can range from R15,000 or more, depending on your needs, so it may be best to start saving early before you become 42.

Other Factors That Can Influence Your Prescription

Other factors can influence an increase in prescriptions, but that is beyond the scope of this article.

The most important thing to understand is that an increasing prescription is not always simple. It may be linked to progressive myopia, accommodative dysfunction, binocular vision issues, eye alignment problems or natural age-related changes such as presbyopia.

This is why a comprehensive eye examination is so important.

Conclusion: Do Not Just Accept a Stronger Prescription Without Proper Testing

If your prescription keeps increasing, it is important to understand why.

Sometimes the change is expected and natural. Sometimes it is linked to how the eye is growing. Sometimes it is linked to the focusing system of the eye. Sometimes it is linked to how the eyes work together as a team.

At our practice, we do not only check if you can see clearly. We also assess how your eyes focus, how they align, and how they work together.

Because vision is not only about clarity. It is also about comfort, function and quality of life.

Call to Action

If your prescription keeps increasing, or if your child’s lenses are getting thicker every year, book a comprehensive eye examination with our practice.

We offer general optometry, family optometry, paediatric optometry, behavioural optometry, binocular vision testing, vision therapy, myopia control options and specialised lenses to help you see clearly and comfortably.

Let us find out why your prescription is changing, and what can be done to help.

Featured Snippet

A glasses prescription may keep increasing due to progressive myopia, especially in children and young adults, accommodative dysfunction from excessive near work, subtle eye alignment problems, or presbyopia after around age 42. A comprehensive optometric examination should assess not only clarity of vision, but also focusing ability, binocular vision and eye health.

FAQ

Why does my glasses prescription keep increasing?

Your prescription may increase due to progressive myopia, accommodative dysfunction, eye alignment problems, or natural age-related changes such as presbyopia.

Why does my child’s prescription keep getting stronger?

In children and young adults, this is often due to progressive myopia, where the eyeball continues to grow, and the lenses become thicker over time.

Can myopia progression be slowed down?

Yes. Specialised myopia control options, such as DIMS lenses, can help slow down the progression of myopia in children and young adults.

Can too much near work affect my prescription?

Yes. Excessive near work can contribute to accommodative dysfunction, where the focusing system of the eye goes into spasm and may create pseudo-myopia.

What is pseudo-myopia?

Pseudo-myopia is when the eyes appear more shortsighted than they truly are because the focusing system is in spasm.

Can eye alignment affect my prescription?

Yes. Subtle eye misalignment can affect accommodation and binocular vision, which may make a patient feel like they need a stronger prescription.

Why does reading become harder after 40?

This is usually due to presbyopia, a natural age-related reduction in the flexibility of the lens inside the eye. It commonly starts around age 42.

Do glasses make your eyes weaker?

No. Glasses do not make your eyes weaker. Prescription changes usually happen because of natural eye development, focusing issues, binocular vision problems or age-related changes.

When should I see an optometrist about an increasing prescription?

You should book a comprehensive eye examination if your prescription keeps increasing, if your child’s lenses are getting thicker, or if you experience headaches, eye strain, blurry vision or difficulty concentrating.