Death of a talking topic

Eye Doctor: Here is your new prescription. You need to add cylinder too.
I: You see I'm wearing under corrected glasses. I think I'll continue with this.
Eye Doctor: But why do you want to wear under-corrected glasses? You would have loss of vision.
I: My previous doctor suggested that I should never go for the exact power lenses. The under corrected glasses would in fact keep the eye power constant. I'm satisfied with it all these years so I would like to continue with it.
Eye Doctor: But those glasses don't have cylinder too.
I: I'm aware of this part. The one before my last doctor had asked me to add it to the lens. However, I started getting headaches after that. My last doctor told me that was not required. Probably, I should stick with my present prescription.
Eye Doctor: No, you shouldn't get any headache. But if you are not willing you can continue with the old prescription.
I: My eye power hasn't changed all these years. I think I should continue with that.
Eye Doctor: But...after 21 years, your eye power won't change much anyway.
I: It won't?
Eye Doctor: No, it won't.
I: ...
Eye Doctor: So, I suppose this is not required and you'll continue with your old prescription.
I: No, I think I'll go with the new one.