I have some prescription-ground work-glasses in tempered glass which cost about half as much as 'ordinary' glasses, they are bifocal (medium and close) and also have shields around the outside. Ask at a 'traditional' opticians for work-wear glasses, the one I used (Dollond & Aitchison) made me an appointment with a work-glasses specialist who sorted me out. Note that you have to specify they need to be tempered glass for silver-soldering, otherwise you get polycarbonate by default.