Glasses for DIY

[Clive Page]

My experience is that they are willing to do it, but charge a few which is greater than the cost of any but the most expensive new frames. So almost nobody gets it done.

[Dave Plowman (News)]

Yes - I'm confusing hyperopia with presbyopia, although the results are much the same as you get older.

[Huge]

I wanted my Varifocal sunglasses reglazed and IIRC my optician wanted ~£200, Specsavers wanted ~£120, but sold me a new pair of sunglasses with the same prescription for £65.

[Dave Liquorice]

The distance and range my eyes can focus at without artifical aid. Essentially I'm now fixed focus at about 6" at lower light levels, high levels of light do make the range a bit wider as the iris stops down.

Presbyopia is hardening of the lens with age, this stops the lens muscles from adjusting the lens shape and thus focus point.

[Dave Liquorice]

They can invert the image but not always it depends on how you are looking through them and the angles involved. Prism in opthalmathtic terms is used to produce a whole image shift to correct double vision.

That's close enough, each density transition will refract the light. The whole air, lens, tears, cornea, existing lens etc need to be treated as a whole and the bits one can tweak, tweaked to get desired result.

[Adam Funk]

+1.

Funny enough, last night I used the "selfie" mode with my phone face-up on the floor in order to see which way round to plug a network cable into the bottom of a powerline network extender in a socket --- I didn't want to unplug it because someone else was using the wifi in the same room.

[newshound]

I've worn glasses since my teens and in those days they always under-corrected, so that I could only just meet the driving test requirement. I *assume* this was to make the eyes "try harder" and thus deteriorate more slowly.

[newshound]

You are thinking of binoculars, which have two prisms. In the lens context, a prism is like a sheet of glass with non-parallel faces, it puts a "kink" in the light beam which lets you correct double vision (where the two eyes don't point in quite the same direction).