IT IS APPROPRIATE, before entering this debate, to begin with definitions. I define primary surgery as a fistulization procedure, with or without antiproliferative drugs, performed as the initial treatment (but allowing other treatments to be given between scheduling the patient for surgery and surgery itself).
Although the effect of surgery is to lower intraocular pressure (IOP), the success of the operation has to be measured against the outcome of treatment: first, whether it halts or adequately slows progression of the disease and second, whether it materially affects the patient's quality of life. The first outcome needs to be measured either by lack of progression of disease at the optic nerve (the ideal), or, by default, lack of progression in the decline of visual fields. The second would be measured by the patient, who would consider whether he or she felt worse as a result of the surgery (for example, by weighing ocular discomfort and blurring of central vision against the potential gain from preserving peripheral vision). To decide whether primary surgery should be considered as the first-line treatment of choice, these 2 considerations need to be taken into account.
Hitchings R. Initial Treatment for Open-Angle Glaucoma—Medical, Laser, or Surgical?Surgery Is the Treatment of Choice for Open-Angle Glaucoma. Arch Ophthalmol. 1998;116(2):241-242. doi:10.1001/archopht.116.2.241