How risky is surgery in a glaucoma patient and what is the success rate. that it will preserve vision?

Minor issue: There are many forms of glaucoma surgery from laser to operative. While the field is constantly changing and improving, most surgeries are well worked out and the success rate is very favorable. Surgery is considered when the response to medication is less than desired. If successful, the internal eye pressure is normalized and the vision will be preserved.

Depends on the patie: How the patient heals, how many prior surgeries or difficult anatomy or co-existing issues, rate of scarring, compliance and persistence, disease response to therapy, etc. Goal is to preserve vision, can look at major trial success rates of lowering pressure.