Originally Posted by Gertrude the Wombat
The CAA recommend against varifocals -
Gertrude,
With all due respect, where on
EARTH did you get that from? Please quote current source. My AME (who used to work for the CAA) says they're perfectly acceptable, much better than the contacts that he wears. I've been wearing Varifocals for over 10 years now with excellent results, instant success rom the first pair. I can go from map to instrument panel to outside without any problems or waiting for my eyes to adjust. I guess we each have our own requirements - good that the bifocal setup suits you.
Generally...
I think that the 'half-moon' type are quite dangerous because you wind up with either a great chunk of frame just across the middle part of your field of view or a major dislocation in your vision, again in the middle of your field of view. One guy I fly with has this problem - not good!
Last time I visited my optician, we had a long debate about where to put the various parts of the prescription across and up the lens, which as resulted in an even better performance from my specs. Like Gertrude, I have a second pair (as required by the regs - do you carry a second pair?) with identical prescription and just as importantly, IDENTICAL optical centres, but with a photochromic tint so that I can go from one pair to the other without having to wait for my eyes to adjust. This is also great for driving, when conditions change from light to dark. Of course, there's a downside, over 800 quid for 2 pairs of lenses, in my existing frames. However, good vision is a first essential for a VHF pilot, so I reckon the cost is balanced by safety considerations.
Cheers,
TheOddOne