"By the mid-1st century AD this meant that glass vessels had moved from a valuable, high-status commodity, to a material commonly available: “a [glass] drinking cup could be bought for a copper coin” (Strabo, Geographica XVI.2)." https://en.wikipedia.org/wiki/Roman_glass

As for manufacturing lenses, you can get by without many tools with cunning techniques. Molten glass naturally forms curved shapes and can be polished by fire. Leeuwenhoek made tiny lenses in the 1600s, although no one knows for sure exactly how (he made a point of not sharing) - one technique that's known to work is drawing the glass into a fine thread, snapping the thread, and heating the end so it forms a tiny ball.