Re: Understanding difference between new & old prescriptions


<newsbirdie2@xxxxxxxxxxx> wrote

A follow-up question: If the glasses for astigmatism for x degrees,
what would be the opposite, and if I wear the opposite would I notice
anything?

You'd double the astigmatism, instead of "neutralizing" it. It'd be blurry.

You can demonstrate it exactly. Fold up your glasses, and put them up to
your eyes in the normal position. Close one eye, then rotate the glasses
around the line of sight of the open eye, so they are vertical instead of
horizontal. In that position, the lens adds to your natural astigmatism
instead of cancelling it out.

(Put another way, if the glasses are the opposite of what I
need, would they then be the same as my eyes and therefore make no
difference?)

No, they'd be twice as blurry as having no correction for astigmatism.

-MT


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