This post is somewhat long, and I apologize for the inconvenience.

I am a 33-year-old male. Prior to 1997, I wore glasses that were -4.25
in the left eye and -4 in the right eye.

In 1997, my eye doctor said that my eyesight was -5, -5. So, I started
wearing -5, -5 glasses for driving, seeing movies in a theater, etc. I
continued to use my -4.25, -4 glasses as reading glasses - for reading,
computer use, etc.

By 2004, the -5, -5 glasses were becoming too weak for driving. My eye
doctor said that my eyesight was now -5.25, -5.25. So, I started
wearing -5.25, -5.25 glasses for driving, and I continued to use the
-4.25, -4 glasses for reading, computers, etc.

For the theater, the -5.25, -5.25 glasses were too strong, and the
-4.25, -4 glasses were too weak. So, for the theater, I used the -5, -5
glasses.

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During the last few months of 2006, some weird stuff started happening
to my eyesight. The -5.25 glasses started feeling inadequate when I
drove, but these glasses did not produce a headache. I tried driving
with the -5 glasses, and I could see a LITTLE less well with the -5
glasses than I could with the -5.25 glasses. Also, the -5 glasses
produced a headache. The headache made the -5 glasses feel STRONGER
than the -5.25 glasses.

Another weird thing that happened is that, on two occasions, the -5
glasses were too strong when I used them to view a movie in a theater.
I had to alternate between the -5 glasses and the -4.25, -4 glasses.

In late 2006, I explained these weird things to my eye doctor, and he
gave me an eye exam. He said that my eyesight is currently -5.125,
-5.125. He said that my eyesight is fluctuating between -5 and -5.25.

He said that, for driving, theater, etc., I could use either the -5, -5
glasses or the -5.25, -5.25 glasses (my choice).

For reading glasses, he said that I could use -4, -4 glasses or -4.25,
-4.25 glasses (again, my choice).

He said that .25 diopter wasn't much of a difference. However, he did
recommend that I use the -4, -4 glasses for the reading glasses. He
said that the -4.25, -4.25 glasses would be too much like a "crutch"
for me.

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Here is the dilemma. The most recent eye exam showed that, with the
-4.25, -4 glasses, I see well in the -4.25 (left) eye, and the image is
somewhat blurry in the -4 (right) eye. Also, lately, I started noticing
that, when I am wearing the -4.25, -4 glasses, I have been getting some
strain or minor headaches in my right eye. So, perhaps that is because
my right eye is struggling to see as well as my left eye is seeing.

So, while I don't want to use -4.25, -4.25 glasses as a crutch, I also
don't want to wear glasses that are so weak (-4, -4) that I have to
struggle to see. I have read that BOTH, using glasses as a crutch AND
struggling to see, are bad for your eyesight.

So, which prescription do I get? -4.25, -4.25? Or -4, -4?

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Also, if the -5 glasses are producing a headache, and the -5.25 glasses
are not producing a headache, does that mean that I have "gotten used
to" the -5.25 glasses? Are the -5.25 glasses my "crutch"?

Thanks for any information, and I apologize for the long post.