Astigmatic glasses - rapid change of parameters?

I hate astigmatism! It has come on lately for me so I now need to correct for it.

I'm terminally farsighted with astigmatism. Correcting my eyes improves my clarity, but it does havoc to my depth perception. The big deal for me is it improves eye strain.

A little optics: Your clarity should not improve by rotating 90 degrees. It should get worse unless for some reason you are changing the aperture (like increasing the f-stop on a camera). This can happen unintentionally should your eye be focusing near an edge of the lens, or alternatively, have a part of the frame (called the temple) in front of the lens and near where you are focusing.

You should also be aware of an illusion. When rotating the glasses, the distortion will rotate with the glasses. This makes what ever you are looking at get fatter or thinner. Your mind can create the illusion that your vision has improved because your brain had been rebelling against the distortion caused by the correct lens. Your brain had already adapted to your current vision, and it doesn't like the new shape have been foisted upon it by your glasses. It feels good to stop looking through the lens even though your vision is not clearer.

Try looking at a small light in the dark. Plenty of these lights on TV sets, stereos, DVD players, etc. Move to where your lens focuses on the point. Rotate the glasses. Things are working properly if the point you are looking at is in the sharpest focus when the glasses are in their normal position.

This just works for your focal point (where your eyes are focuses). Your peripheral vision may not be perfect which is annoying and is something you have to live with.

(You might also look into whether your astigmatism was overcorrected for reasons I won't go into now)

Anyhow, it sounds like you are due for a check up. But it is good to learn what is going on with your eyes before you go in.

good luck.

**************Addendum**********

I've been thinking about optics some more. The other thing about looking through glasses is that you change the focus depending on how far they are from your eye. Things might look better at 90° because everything is in focus along one axis, but not the other which would be a bit blurry. But if you squint a little than that too would come into focus. Whereas the proper alignment might be out of focus along both axises.

So when you do your tests, the glasses have to be in the correct spot with respect to your eyes, and what you are looking at has to be at the correct distance per the focal point of the glasses.

Your question ended up being quite interesting.

If your prescription changes frequently, and you like your frames, you should try getting the lenses replaced every so often through an online company. www.replacementlensexpress.com lists really great prices and I know the quality is high.

If you already have frames, you'll need to send these in. If you really can't part with your frames, there's a chance that they already have the template. In this case, e-mail them the make and model number (found on the side of the frame, or the "temple") and ask if they can cut the lenses without you sending in the frame. Here's their e-mail: info@replacementlensexpress.com.

Good Luck!

When you first got your glasses, do you remember that your vision through them was as clear as compare to now you're seeing when you rotate them at right angles?

If No then your optician have made your glasses 90 deg off axis.

If Yes, then it's possible for your astigmatism to change 90deg, if your cornea transplant buckled... best to consult with you eye surgeon again, get another corneal topography map done to see what your cornea is doing.