A Cochrane review (abstract , review [Abstract]) [withdrawn from publication] included 8 studies with a total of 353 patients. Only three studies focussed on patient relevant outcomes. The largest study (CNTGS 1998) included 145 eligible participants of 230 people enrolled who had to show progression to become eligible. As 37% were not included the generalisability of the study results remains questionable. In this study the aim was a reduction in intraocular pressure (IOP) of 30% in one eye by pharmacological interventions and / or trabeculectomy. The use of systemic vasoactive drugs such as beta-blockers and alpha-agonists was excluded. Furthermore, the study was carried out before the introduction of topical carbonic anhydrase inhibitors and prostaglandins. The only mentioned pharmacological intervention was systemic application of carbonic anhydrase inhibitors. The endpoint, visual field loss or optic disc damage progression did not differ between the intervention and the control group (22/66 and 31/79 respectively). Cataracts occurred more frequently in the intervention group compared with the control group (23/66 and 11/79). When the visual field progression was adjusted for cataract a statistically significant effect of the surgical and/or medical combined treatment approach was observed (10/66 versus 29/79). In one trial a beneficial effect of lowering intraocular pressure was found, but only if data were corrected for cataract development. In two small studies a beneficial effect on visual field loss of brovincamine, a calcium antagonist was reported.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment) and by imprecise results (few patients and wide confidence intervals).
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