Quantifying the effect of intraocular pressure reduction on the occurrence of glaucoma.
OBJECTIVE
To estimate the effect of reducing intraocular pressure (IOP) on: (i) the incidence of primary open-angle glaucoma (POAG) in patients with ocular hypertension (OH), and (ii) the progression of glaucoma.


METHODS
A meta-analysis of relevant randomized controlled trials was conducted. A literature search was performed to identify trials with: a randomized comparison of IOP-lowering intervention versus placebo or no treatment; visual field loss or optic disc changes as outcome; and follow-up >6 months. A pooled relative risk (RR) was calculated by a random effects model. Risk reduction of glaucoma conversion per mmHg of IOP reduction was quantified in a meta-regression model.


RESULTS
We identified nine OH and one POAG trials. A meta-analysis of OH trials gives a pooled RR of 0.61 [95% confidence interval (CI) 0.45-0.83]. A meta-regression shows a decrease of the RR of glaucoma conversion by 14% with each mmHg extra IOP reduction (P = 0.045). No meta-analysis of POAG trials was performed because only one study has been identified.


CONCLUSIONS
There is sufficient evidence that OH therapy reduces the risk of conversion to glaucoma. This risk reduction increases with greater IOP reduction.
Department of Ophthalmology, Maastricht University Hospital, The Netherlands.
Andrea
A
Peeters
Carroll A B
CA
Webers
Martin H
MH
Prins
Maurice P
MP
Zeegers
Fred
F
Hendrikse
Jan S A G
JS
Schouten
D018450:Disease Progression; D005902:Glaucoma, Open-Angle / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D009798:Ocular Hypertension / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D016032:Randomized Controlled Trials as Topic; D012306:Risk; D040242:Risk Reduction Behavior