Adjustable fresnel lens glasses

These glasses have flat lenses. The rear half of each is a Fresnel lens consisting of a thin layer of silicone oil behind transparent piezoelectric crystals linked to an array of indium tin oxide electrodes, and a thin protective flat layer at the front filled with another clear substance with a melting point somewhat above body temperature, probably a heavier siloxane. Passing a current through the crystals changes their shape and the refractivity of the whole lens changes. Different patterns of current are possible in different parts of the lens, allowing for astigmatism. The lenses are adjusted by turning on heating elements to melt the substance at the front, then twiddles with the controls until the lenses are comfortably focussed. While holding that pattern, the lenses are then cooled back to body temperature, allowing them to freeze in position. This is done whenever the user experiences a change in their eyesight. They are sold with a Snellen chart, an ophthalmoscope with a fibre-optic attachment allowing one to do fundoscopy on one eye while looking through the other and assess the likes of papilloedema, diabetic eye changes and blood vessel changes, a booklet introducing one to optometry and a disclaimer concerning the need to consult a professional optician. The ophthalmoscope also has a USB attachment to upload images of the retina to a crowdsourced ophthalmology website.

One flaw in this, of course, is whether piezoelectric crystals are ever transparent.

It also makes lenses flatter, thinner and lighter.