Indications of trabeculectomy in open angle glaucoma

The indications and frequency of trabeculectomy operations in Swedish eye clinics in 1980 and 1981 were assessed. The incidence of operations are significantly higher in the north than in the south of the country. The geographical influence was eliminated by excluding the 6 northernmost clinics, but the frequency of operations still varied with a factor of nearly 5 between the clinics. Most clinics seemed to allow individual modifications and exceptions to the rules of indication for surgery. An IOP surpassing a certain limit, locally fixed but varying greatly between clinics, was an indication in most places, even if the visual field was normal. An optic disc defect alone was an indication for surgery in one clinic only. In most clinics a progression of the glaucoma visual field defect with or without disc damage was an indication of surgical intervention.