Heijl 2000.

Methods	RCT. Double‐masked. Placebo controlled.
Participants	90 people with OHT, 37% (timolol group) and 23% (placebo group) had PEX or PDS. Racial constitution is not reported. Inclusion criteria: mean untreated IOP of 22 mmHg or more, normal visual fields (Competer and Goldmann), open angles by gonioscopy, one of the following risk factors: suspicious disc, positive family history, PEX or pigment dispersion syndrome, diabetes, mean IOP of at least 27 mmHg without additional risk factors. Exclusion criteria: mean untreated IOP of 35 mmHg or above, medication known to affect IOP, history of intraocular surgery, visual acuity of 0.3 or less.
Interventions	Timolol 0,5% twice daily. Placebo.
Outcomes	Incidence of glaucomatous visual field defect.
Notes	10 years follow up, for better comparability with the other trials data concerning 5 years follow up were used for meta‐analysis. 49 drop‐outs within 10 years (26 timolol: 2 due to adverse reaction; 23 placebo: 1 due to adverse reaction). 33 drop‐outs within 5 years (19 timolol: 2 due to adverse reaction; 14 placebo: not related to adverse reactions).
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Low risk	A ‐ Adequate