Self-Adjusting Lenses For Eyeglasses

From Washington Post:

The glasses work on the principle that the more liquid pumped into a thin sac in the plastic lenses, the stronger the correction.

[Joshua Silver] has attached plastic syringes filled with silicone oil on each bow of the glasses; the wearer adds or subtracts the clear liquid with a little dial on the pump until the focus is right. After that adjustment, the syringes are removed and the “adaptive glasses” are ready to go.

Currently, Silver said, a pair costs about $19, but his hope is to cut that to a few dollars.

This is interesting for several reasons:

1. It increases the flexibility of a single pair of eyeglasses for different situations.
2. It allows the entire field of view to be the same focal length, unlike a bifocal or multifocal lens that has only a small region at the required focus and everything else off-focus.
3. It decreases the long-term cost by allowing eyeglasses to adapt to changing eye-lens powers over many years (assuming the glasses last that long).
4. It’s a clever emulation of what nature does for the eye-lenses of most species: make them fluid-filled and change their shape with muscle tension.

Overall, seems like a design that solves several problems simultaneously. Quite impressive.