The first glasses as such were created between 1270 and 1290 in Italy, specifically in Murano (a small island north of Venice) using its famous Murano glass factories. The first glasses made there were used to treat presbyopia and consisted of a convex ground lens. A century later, concave lenses would arrive to correct myopia. The formulas for creating this magical glass by the Murano cristalleri were a state secret that could not be shared with anyone. In fact, the cristalleri or glassmakers were prohibited from leaving the island, and anyone who found them could be sentenced to death. violated this rule.