Milen wrote:
I am 30 years old and I have been wearing glasses for about 15 years.
Recently I broke my old spectacles and bought a pair of new ones - almost identical frame as the previous one (thin titanium) just a smaller lenses.
It’s been two weeks with the new glasses and I experience pain in both my eyes as if I got a constant muscle strain. The prescription is exactly the same as the old ones. I have been going back to the optometrist two times - the first time she changed the alignment/fitting of the frame which seemed to help a bit but I still got the hurt in the eyes. The second time she adjusted them again thus making it worse! We tested the eyes and the lenses thoroughly but they are perfectly OK (same numbers). The optometrist is completely out of clue! What could be the reason for the pain and is it possible to damage my eyes in the long run?

ANSWER

Milen,
The fact that a change in the fitting of the frame can increase or decrease your symptoms is indicative of optical distortions caused by your new glasses. One of the causes of such a problem could be a change in the curvature of the anterior surface of the glasses (called base curve of the lens). Even if the numbers of the prescription are the same, a curve that is (often-times) flatter than the older one will create optical distortion than can induce your symptoms. The change of a base curve is made when it is determined by the manufacturing lab, considering the shape, the size and the profile of your frame, that the older one is not appropriate. Keeping the old one will lead to producing lenses that will be too thick or will be difficult to cut and edge to fit in the frame). Another possibility is that one of the lens was cut and edged too tight (or large) for the frame. Once inserted, a too tight lens will be compressed and optical distortions can occur from this.

During the manufacturing process, some waves can also be induced. If they do not affect the center of the lenses, they cannot be detected by the reading of their power.
There are no long term effects of these problems. This is discomfort coming from optical distortions. Once the glasses are removed, the eyes remain in perfect shape. If you continue to wear defective glasses, however, discomfort will continue and may cause headaches and malaise but it’s nothing irreversible.

Many thanks for this interesting question,
Langis Michaud
Associate professor – U de Montréal

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