The Antiques Council gives a little information on convex mirrors:
Convex mirror is the generic term for a reflective glass surface that is in a convex, or outwardly rounded, shape. Unlike a "looking glass" that is a flat plane of surface-reflective glass showing a "mirror image," convex mirrors distort the reflected perspective to capture light at angles within a room, allowing a wider field of vision and reflection than a looking glass permits.
Convex mirrors are seen in Dutch paintings as early as the 15th century, and the mirror form is also recorded in documentation from Germany of the same period.Encyclopaedia Britannica 1911 edition had this to say:
A gild of glass-mirror makers existed at Nuremberg in 1373, and small convex mirrors were commonly made in southern Germany before the beginning of the 16th century; and these continued to be in demand, under the name of bull'seyes (Ochsen-Augen), till comparatively modern times. They were made by blowing small globes of glass into which while still hot was passed through the pipe a mixture of tin, antimony and resin or tar. When the globe was entirely coated with the metallic compound and cooled it was cut into convex lenses, which formed small but well-defined images. .... It was, however, in Venice that the making of glass mirrors on a commercial scale was first developed; and the republic enjoyed a much prized monopoly of the manufacture for about a century and a half. In 1507 two inhabitants of Murano, representing that they possessed the secret of making perfect mirrors of glass, a knowledge hitherto confined to one German glass-house, obtained an exclusive privilege of manufacturing mirrors for a period of twenty years.Going through other images, I started finding a few more representations, such as the following:
The Seven Deadly Sins: Vanity (or Pride) Detail (c1485) by Hieronimous Bosch
Vanity (c1485) by Hans Memling
Diptych of Maarten Nieuwenhove (1487) by Hans Memling
The Moneylender and his Wife (1514) by Quentin Massys
There is also a collection of images with convex mirrors in this blog and more images on Larsdatter.com. I even found modern representations for these mirrors, but $129 for the small size is a bit pricey for me.