Pinhole glasses originated in Germany in the 1890s and became
fashionable for a while with the well-to-do. During World War
One their usage died out. Curiously, they remained popular in
Australia and South Africa and in recent years become very popular
in the USA. In Britain, opthalmologists and opticians are divided
over the value of pinhole glasses.
The improvement in the eye to focus while using pinhole glasses
has long been understood (pinhole cameras were the first cameras
and the pinhole principle is the basis of certain eye tests).