We often hear our patients coming to our practice wanting to “increase” their current prescription glasses, hoping that would make their vision better. But is that the case?
Understanding What Your Prescription Means
Your optometrist gave you a prescription previously perhaps a couple of years ago for some new glasses. Your optometrist discussed that your eyes had gotten “worse” and the prescription had “increased” to make your vision clearer again.
Your prescription is tailored to you and your eyes. It would work effectively for your friends and family. Just like prescriptions for medications, the dosage is unique to you prescribed by your doctor.
Your optical prescription contains the power of lenses required to optimise your vision for the distance and near. Your optometrist determines this prescription by understanding what your vision requirements are and from what level of vision you have when you’re not using your glasses.
The power of the lenses refracts or bend light rays in a way to keep the image in sharp focus the back of the eye. Your optical prescription determines this power required to achieve that. “Increasing” the power of the lens may not necessarily make your vision any better as it won’t keep the image in sharp focus any more.
A Change In Prescription
If you have noted a change in your vision, it could mean that your prescription has changed. The change may not necessarily mean an increase in the prescription of your lenses.
Think about how a projector works in a cinema. The lens in front of the projector is designed to focus the image or video sharply on the screen. The power the lens required is determined by how far the projector is from the screen. If you have noted a change in your vision, a change in the power of the lens is only one factor. As you can imagine, there would be multiple factors why the image on the theatre screen could appear blurry.
Someone could’ve bumped the projector either forward or backwards, putting the image slightly out of focus. You could either move the projector back to where it was or change the power of the lens. Whether you needed to increase or, decrease the power depends on how the projector is shifted.
Vision Can Change Without a Change in Prescription
From the previous example, you can appreciate that it’s not as simple as just increasing your prescription to make your vision better. Just like our projector example, multiple factors can affect the quality of the image, which also holds with our vision.
If your image for your projector is blurry, it could be the cloudy lens; someone could’ve put their fingerprints all over it when handling it. The screen could be wrinkly or dirty with lots of dust and debris. Our eyes are subjected to similar problems such as cataracts (cloudiness of the natural lens) and macular degeneration (imperfect screen).
This is why when our patients experience a change in their vision, along with checking their refraction (prescription), we also need to make sure the rest of the eyes are in working order.
The Bottom Line
It is often hard to appreciate that a change in vision can be caused by other reasons than just a simple change in one’s prescription. Vision changes due to prescription changes are often gradual and could take years. Hence we recommend having your eyes examined every two years. A sudden change in vision can often be a sign of something sinister and needs to be evaluated promptly. If you are experiencing any vision issues, visit us at Capital Eye to have a complete understanding of your eye health.