AdSpec adjustable power lenses

[Pete Hanlin]

A company named Adaptive Eyecare has brought out a new "adjustable ophthalmic lens" recently. Developed by professor Joshua D. Silver, the new lenses are adjustable by varying the amount of fluid in the lens (adj. by up to -/+ 6 diopters).

The lens will probably not pass drop ball tests, so they won't be available here, but what's the deal with these lenses? How would you adjust cyl power independant of sph power?

Just wondrin',
Pete

[shanbaum]

Originally posted by Pete Hanlin:
A company named Adaptive Eyecare has brought out a new "adjustable ophthalmic lens" recently. Developed by professor Joshua D. Silver, the new lenses are adjustable by varying the amount of fluid in the lens (adj. by up to -/+ 6 diopters).

The lens will probably not pass drop ball tests, so they won't be available here, but what's the deal with these lenses? How would you adjust cyl power independant of sph power?

Just wondrin',
Pete

I think they might pass drop-ball tests - as I understand it, the lenses are basically little bags; I'd guess that the containing surfaces must be made of a fairly elastic material. It'd be like dropping the ball on a little pillow.

They are limited to spheres, and are intended for use in very poor areas; their only benefit is their low cost.

[Darryl Meister]

I would imagine that a cylindrical component could be incorporated by using a membrane material whose elasticity varied horizontally. (Similar to a piece of material you could stretch in one direction but not another.) This simplest, non-chemical means to accomplish this might be to vary the thickness of the membrane. This would allow a separate, rear chamber to be filled with the fluid and produce cylinder power as the curvature increased through one meridian (like a simple cylinder). The sphere power could be provided by a separate, front chamber.

Best regards,
Darryl

[John R]

If i rember right these types of spec were shown a few years back here in the UK. They were to be used in the 3rd world countries by optical doc's going to treat poor people from these countries who could not afford specs and they were a way of not having to carry large ammounts of stock around with them, I think they used a syringe to fill the "sack / lens" with a fluid till the patient could see best.

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[Dave Nelson]

I actually ran into an article in popular mechanics circa 1960, which incorporated a fluid system. it used a very thin, flexible glass "membrane" which broke by cleaning it.