Eyeglasses

Eyeglasses, also known as glasses or spectacles, are a vision aid technology consisting of glass or crystal lenses mounted in frames made of wood, metal, and/or bone. The frames position one lens over each of the user's eyes, and typically rest on the nose and ears. Lenses are carefully calibrated to magnify objects to a precise, minute degree, correcting for vision impairments caused by factors such as genetics or age. 

History

Magnifying lenses have been used since at least the Age of Integrity, though usually held up to the face either directly or by a handle. Similarly, frames holding protective or magical lenses in front of the eye have been around since the Y100s of the current age. Such lenses, usually of clear glass or lightly tinted crystal, allowed a user to see normally while protecting their eyes from harsh light or trauma caused by physical and magical hazards.
The earliest recorded instance of someone combining the two technologies was in Y1006 by the dwarven physician and cleric Ernst Bjoltan. Ernst wrote of the invention in his journals:

Confound this blasted decay of age! I miss the years gone by when I could cast with one hand, write with another, and still see the glyphs on the page in front of me. I have my magnifying lens, but it be quite a task enchanting it to float where I need while still working on other spells... I am working on a mundane solution to this consternation. As it is winter, dear Janssen has put away his sun spectacles-- perhaps I can affix a magnifying lens to them. Such a mundane solution would free up my magical energy... not to mention my blasted hands...

Construction

Eyeglass shops (glasseries) are typically staffed by clerics, alchemists, and diviners, as well as mundane craftsmen such as metallurgists, mechanics, or woodcarvers (depending on the frames offered). When fitting a customer for eyeglasses, a cleric first guides them through a series of questions and meditations that allow the diviners to functionally "see" through their eyes, determining what vision issues need to be corrected and to what degree. Alchemists carefully mix quartz and silica glass and shape it to the specifications the cleric then diagnoses. Once the lenses are built and their effectiveness confirmed with the customer, mundane craftsmen craft and fit the frame to the customer's face. Lens shapes are largely determined by the customer's needs, but there is often some ability to accommodate the customer's aesthetic preferences as well.