On Tue, 27 Aug 2019 21:25:13 +0100, "dennis@home"
wrote:

On 27/08/2019 17:22, Bert Coules wrote:
They do look intriguing.* I use and like varifocals but there are times
(and in differing circumstances) where they're not ideal and a single
prescription pair would be better.* These might fit that bill.

IIRC they showed something similar on tomorrows world a long time ago.

They have also been suggested for third world countries too, using cheap
syringes for the fluid.

I think these don't have fluid - in fact I was looking for variable
glasses some time ago, and nobody makes that type. These glasses have
two sliding lenses giving different strengths depending on sideways
separation. However it can't really be done because the horizontal
power will not be the same as the vertical power, resulting in
astigmatism, but seemingly not noticeable judging by the glowing
reviews.
--
Dave W