Re: Some questions about vision.

On Sun, 30 Oct 2005 13:46:38 -0500, Marilee J. Layman
<mjlayman@xxxxxxxxx> wrote:

>On Sat, 29 Oct 2005 21:46:57 -0400, "John W. Kennedy"
><jwkenne@xxxxxxxxxxxxx> wrote:
>
>>Marilee J. Layman wrote:
>>> Erm, my progressive bifocals are convex. All my glasses have been
>>> convex. My eyes are still getting too long -- I have to wear contacts
>>> two hours a day to slow them down.
>>
>>I rather fancy your glasses, like most other glasses, are convex in
>>front and concave in back. And I think if you look at them in profile,
>>you'll see that the /net/ shape is concave.
>
>If you're looking from the back, yes. I was thinking of looking at
>them from the front.

I had been talking about the net shape of the lens. Even for
nearsighted people, the front surface is usually either flat or
slightly convex.

--
John F. Eldredge -- john@xxxxxxxxxxxxxx
PGP key available from http://pgp.mit.edu
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexandria
.

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