Dolland and Aitchison have a lot of branches that test the efficacy of coloured lenses ask at your local branch and see if they know a local optician that does the test if they don't do it in your area.
As a quick check invest in a set of coloured plastic A4 wallets (about £1 for five) at your local stationers.The pack contains one each of blue, yellow, pink, green and clear. Slip them one by one over a page she's reading and see if any colour helps. Not an exact science but cutting down the glare from white paper might help a bit and you never know, you might just get lucky.
Mary