I would recommend plastic lenses and the progressive bifocals if you need
those. The progressive (lineless) bifocals do work well with a computer
screen. I shifted to plastic about three months ago and would never go back
to glass. The light weight is so much more comfortable when you must wear
glasses all day long. Invest a few dollars in a microfibre cleaning cloth
and a bottle of lens cleaning fluid and you will not have to worry about
scratches. I also use the photogray lenses which work very well if you are
at all light sensitive.