Comparison 1. Surgical failure.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 IOP > 21 mmHg 12 months or more after surgery	4		RR (Fixed, 95% CI)	0.23 [0.14, 0.40]
1.1 Black African people	1		RR (Fixed, 95% CI)	0.21 [0.11, 0.40]
1.2 Caucasian people	2		RR (Fixed, 95% CI)	0.15 [0.02, 1.28]
1.3 Chinese people	1		RR (Fixed, 95% CI)	0.34 [0.12, 0.96]