FAQ About Glasses and Prescriptions

The doctor said that my prescription did not change much but the numbers are different. What does this mean?

My prescription changed. What does this mean?

Did my prescription change?

When you look at your last eyeglass prescription and your new one, the numbers are almost always different. So, in everyone, the prescription changes from exam to exam, so, yes your prescription changed. But this is not a very good way to look at your eyes or eyeglass prescriptions. Doctors look at something else-how much does a change in prescription affect vision. Many times the prescription numbers will change from one exam to the next, but the vision (how many letters you can see on an eye chart) will be the same from one prescription to the other.

So, it often happens that a doctor will say that things didn’t change much, but the prescription will be different. This means that you see well with the old and new prescription but the new prescription is a little different. Another way to look at this, is that the doctor is telling you that it is up to you if you want to get new glasses, but do not expect the vision to be very different from your old glasses.


What is the number of my prescription?

That’s an easy question and there is no good answer. When patients ask what their number is, they are thinking of the single number on a pair of glasses they see at the drugstore. You know, +1.50 for example. This is only one part of an eyeglass prescription, and does not take into account the

  • eyeglass prescription for distance only has 3 numbers for each eye. If it is a bifocal prescription, then each eye has 4 numbers.
  • the difference between the eyes. So each eye is usually different so that means your eyeglass prescription has 6 numbers at a minimum. If it’s a bifocal prescription, then that’s 8 numbers total.

Doctors can’t answer that question of what is the number.

I want to know if I’m getting worse…what should I ask?

Don’t ask did my prescription change. The prescriptions change every time you are examined so the answer is always yes, it changed. And, if you ask did I get worse, there is no answer to that question either. Doctors look at an eyeglass prescription not as better or worse but how much of a change was found and if the patient is able to see better with the new prescription.

The best question to ask is, “if I get new glasses will I see better than with the old ones?”

If my eyeglass prescription changes what does this mean?

In almost every case, a change in eyeglass prescription simply means you need new glasses. It does not often mean that it will continue to get worse, and it does not usually mean that you’re going blind.