News: EYE Nova Eye Medical To Raise A$8M For Expansion Of Glaucoma Surgical Device Business, page-39

Well I take 3 drops a day & I can tell you it's not much fun. my eye is constantly irritated & sore (more than 1 drop increase the chances of a reaction) compliance is an issue because you can forget or run out, they expire after 28 days, if you accidentally touch the eye there's a chance of infection, they're expensive. The effect starts to wear off during the day I'm relatively young but there's a certain amount of coordination required to put the drops in the eye that older people might not have etc etc
I would rather have the drops than the major op which is the trabulectomy which has major risks associated with it but from what I know this is a minimally invasive op with very little risk