Every surgery can have complications and glaucoma surgery can't be exceptive. Failure to treat glaucoma can result in permanent blindness. Some patients will bleed during or after the surgery and get infected if not cared properly. But few people can have these complications as glaucoma surgery is quite safe and effective.
Bleeding, infection, discomfort, and pain are common among conventional glaucoma surgery and it has much to do with the doctor's skill and Operation conditions. But generally glaucoma surgery results have a very high success rate. You should balance the risks and benefits before surgery and talk to an ophthalmologist in detail about potential glaucoma surgery complications.
Having glaucoma surgery may suffer some complications, such as a small risk of cataract formation which may need another cataract surgery to treat it and a short-term increase in eye pressure or an excessive drop in pressure.