Glasses change the appearance of the makeup underneath them in ways nobody writes about, and the direction depends on your prescription. This matters because a very large proportion of the people this site is written for wear glasses every day.
A positive prescription — reading glasses, or long-sightedness — magnifies. Everything behind the lens appears larger: the under-eye area, any crease, any line of pigment in it, any patch of powder. If you have ever wondered why your under-eye looks fine in the mirror without glasses and heavy with them on, that is the reason. The correct response is less product and a thinner formula, because the lens is going to amplify whatever is there.
A negative prescription — short-sightedness, the more common one — shrinks. The eye and the surrounding area appear slightly smaller behind the lens, which is why people who are short-sighted often find their eye makeup disappears. Here you can afford slightly more definition than you otherwise would, particularly on lashes and brows.
The third factor is mechanical and applies to everyone: frames touch your face. Nose pads sit on either side of the bridge and rub; the bridge of the frame can cast a shadow; and the lower rim of a heavy frame can press on the top of the cheek. Those contact points are where concealer transfers onto your glasses and where makeup wears off first.
The fourth is shadow. A frame casts a real shadow beneath it, particularly a thick or dark one, and that shadow lands on exactly the area you were trying to brighten. Some of what people treat as a stubborn dark circle is their frame's shadow, and no amount of concealer fixes it — see the eye-makeup side of this in how to apply makeup when you wear glasses.
