Why Do My Old Glasses Work Better Than My New Ones?

In this article, you will learn about the limitations of the lens designs and why in some cases your old glasses work better than your new ones. In most cases, pitfalls for the glasses are the centration and the prescription itself. But why in some cases the measurements get reaffirmed after you spend some time in the optical shop and still your old glasses work better than the new ones.

If this sounds like the situation you are in this article is exactly for you. When the measurements get made oftentimes one puzzle is missing. How does the topography look like? Those are the measurements for the cornea and tell the person that performs the measurements a bit more how you will respond to your new glasses.

The shape of the cornea tells you if multiple powers on your cornea are present. Usually, the topography is pretty consistent, and therefore glasses just work in most cases. But in some cases, the variety of the corneal shape (radii) is so different that the prospect notices the discomfort or shadow-like effects with the new prescription.

When the old lenses get tested they are also not perfect but they work better. The reason is they cover a bigger part of the needed present RX.

Here in the picture above you can see such an example of a topography. It is a powermap and what it shows is the different values of diopters distributed on the surface of the cornea. What is important here is the area directly in front of the pupil.

The customer with this topography has decent visual acuity with glasses. What the glasses do is compensate for the part where you see lighter and darker green colors. What the glasses can not compensate for is the yellow part in the lower part. She only has problems at night with other headlights.

Because when the environment is less bright her pupil will get bigger and suddenly the powermap in front of her pupil should contain more yellow. But the glasses can only correct one value.

But Why Do My Old Glasses Work?

Oftentimes the old glasses worked because they delivered the best results in most situations so the wearer did not feel the limitations of the glasses as much. Depending on the condition of the cornea, the tear film, and your physical condition in general the measurements of the prescription could vary on a day-to-day basis.

What to Do When the Old Glasses Work Better Compared to the New Ones?

The prescription of general resembles a snapshot. When the person has dry eyes the optimal lens power could be off-target by up to two diopters. One method to see if one prescription would work is to test it multiple times on different days. This testing should be done ideally by the same optician/optometrist to reduce variation during the testings.

That way the wearer and the optician will have more data and can see easily if the prescription would work on most days. If not a different route needs to be taken because glasses, in general, can only correct one lens power for one prescription. When the lens power needs to be changed and dry eyes are a topic to be considered the process with warm compresses and massages on the lids can take a couple of weeks/months until the variations in the prescription disappear and the eye shows the optimal prescription.

Dry eyes are pretty often the cause when new glasses do not work as intended despite the causes mentioned above. But in some cases the tear film is ideal and the shape of the eye is just not optimal for a correction with glasses.

In those cases, rigid gas permeable contact lenses can be a great alternative. The reason, therefore, is the lenses span the uneven areas on the cornea, and the gap between gets filled with the fluid from the tear film. The result then oftentimes is a visual acuity that exceeds the experience with the glasses.

How You Should React When Your Old Glasses Outperform the New Ones?

Talk to your eye care specialist. Try to gather data when the new glasses work and when they do not. I will give you a few examples below.

  • Do the old glasses work better in both eyes?
  • Do the old glasses make problems at a certain distance?
  • When you look at characters do they have a shadow-like effect and does the shadow change in regards to the angle you see it. These changes could be observed after each time blinked or from day today. Just make sure you look at the same things every time you want to test things.
  • Make your observations at least for seven days to gather enough data.

A good craftsman will understand the situations and will be happy to get some information to work with. This just happens from time to time and as described above there are multiple ways to deal with those situations. Also when you already bought new glasses do not think you blew your money. The reason is usually opticians or eye clinics have the ability to return the lenses and order new ones when the same manufacturer is used. Just ask your eye care professional how they deal with those cases and if you can return the lenses.

No professional wants to have an unsatisfied customer.

When you dealing with a situation like this it is good to read into the causes of problems with glasses a little more. I highly recommend you read my article about anisometropia in combination with progressives and problems with progressive lenses in the reading area.

After you read them you can communicate easier with your eye care specialist and understand more about what he plans out as a solution to the problem you have. Communication can sometimes be hard this is why it helps when your eye care specialist is quite experienced and just knows what you mean when describing the problem.


When the old glasses work better compared to the new ones the cause will be found by your experienced eye care specialist. In some cases, this leads to a recommendation the wearer of the glasses does actually no want to use rigid gas permeable contacts to produce optimal results.

When the wearer wants to stay with glasses and not use the solution described by the optician/optometrist the lens power can only be adjusted to a level that is as good as possible. The question here is does a change in lens power really solve the issue? Or does it just makes some things better while some other things get worse?

When the eye care specialist does not see a real jump in terms of the performance with the type of correction another solution should be considered. The solution can be very different depending on the individual case.

I wish you a great day.

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