Contact lens is not the invention of 20th century but of 19th century.
Yes, it is true, the first ever glass contact lens was made in the year 1888 by a German ophthalmologist named Adolf Fick. But the the modern day contact lens was invented by Otto Wichterle in 1972.
Our eyes get oxygen directly from the environment unlike other parts which get oxygen from blood. So the early glass contact lens could be used only for 4 hours. But the modern day extended wear lens can be used day and night for as long as 30 days.
There are over 125 million people globally who wear contact lenses. The majority of the contact lens wearer are women being 87%.