Ocular Perfusion Pressure and the Risk of Open-Angle Glaucoma: Systematic Review and Meta-analysis

Abstract

Low ocular perfusion pressure (OPP) has been proposed as an important risk factor for glaucoma development and progression, but controversy still exists between studies. Therefore, we conducted a systematic review and meta-analysis to analyze the association between OPP and open-angle glaucoma (OAG). Studies were identified by searching PubMed and EMBASE databases. The pooled absolute and standardised mean difference in OPP between OAG patients and controls were evaluated using the random-effects model. Meta-regression analysis was conducted to investigate the factors associated with OPP difference between OAG patients and controls. A total of 43 studies were identified including 3,009 OAG patients, 369 patients with ocular hypertension, and 29,502 controls. The pooled absolute mean difference in OPP between OAG patients and controls was -2.52 mmHg (95% CI -4.06 to -0.98), meaning significantly lower OPP in OAG patients (P = 0.001). Subgroup analyses showed that OAG patients with baseline IOP > 21 mmHg (P = 0.019) and ocular hypertension patients also had significantly lower OPP than controls (P < 0.001), but such difference in OPP was not significant between OAG patients with baseline IOP of ≤21 mmHg and controls (P = 0.996). In conclusion, although no causal relationship was proven in the present study, our findings suggest that in patients with high baseline IOP, who already have a higher risk of glaucoma, low OPP might be another risk factor.

Figure 1

Flow diagram of the study selection process.

Figure 2

Random-effects meta-analysis of ocular perfusion pressure (OPP) difference between open-angle glaucoma patients and controls. Pooled OPP difference was presented as (A) the mean difference (MD) and (B) the standardised mean difference (SMD) with 95% confidence interval (CI). SD = standard deviation.

Figure 3

Random-effects meta-analysis of the mean ocular perfusion pressure (OPP) difference between (A) primary open-angle glaucoma (open-angle glaucoma [OAG] patients with baseline intraocular pressure [IOP] of>21 mmHg), (B) ocular hypertension, (C) normal-tension glaucoma (OAG patients with baseline IOP of ≤ 21 mmHg) and controls. SD = standard deviation; MD = mean difference; CI = confidence interval.

Figure 4

Random-effects meta-analysis of the standardised mean ocular perfusion pressure (OPP) difference between (A) primary open-angle glaucoma (open-angle glaucoma [OAG] patients with baseline intraocular pressure [IOP] of>21 mmHg), (B) ocular hypertension, (C) normal-tension glaucoma (OAG patients with baseline IOP of ≤21 mmHg) and controls. SD = standard deviation; SMD = standardised mean difference; CI = confidence interval.

Figure 5

Random-effects meta-regression of standardised mean difference in ocular perfusion pressure (OPP) between patients with open-angle glaucoma (OAG) and controls according to (A) proportion of men and (B) mean OPP level. The line represents a line of best fit from meta-regression analysis. This suggests that the standardised mean difference in OPP levels between patients with OAG and controls was the largest in study population with large proportion of men (P = 0.040) and low mean OPP level (P = 0.029).