My father had a trabeculectomy last year, to treat the rising pressure. It does seem to have worked, and the pressure in his eye now seems to be consistent and within the normal reference range.
They are monitoring him because there was a suggestion that he might need one in his other eye, but so far so good.
The surgery was carried out as a day case, with no side effects. The only downside, such as it was , was the need for a strict adherence to antibiotic drops for - I think - around 3 weeks.