Table 2.

Stratified analysis for the lutein or/and zeaxanthin or/and meso-zeaxanthin supplements effect on macular pigment optical density (MPOD) across the assessed randomized controlled trials (RCTs).

Subgroup	AMD Patients					Healthy Populations
	N	WMD	95% CI	Pz	Ph	N	WMD	95% CI	Pz	Ph
Dose of supplement
>10 mg	10	0.07	0.04, 0.12	<0.001	0.93	15	0.12	0.09, 0.15	<0.001	0.01
≤10 mg	4	0.09	−0.07, 0.19	0.40		4	0.05	0.03, 0.07	0.02
Duration of intervention
≥12 months	11	0.17	0.09, 0.24	<0.001	0.05	6	0.07	0.04, 0.10	<0.001	0.83
<12 months	3	0.05	0.01, 0.09	<0.001		13	0.08	0.03, 0.13	<0.001
Mean age
>70 years	7	0.06	0.03, 0.09	<0.001	0.85
≤70 years	7	0.11	0.02, 0.19	<0.001
Zeaxanthin
With	9	0.07	0.04, 0.11	<0.001	0.60	11	0.09	0.06, 0.13	<0.001	0.21
Without	5	0.08	0.07, 0.09	0.41		8	0.08	0.03, 0.08	0.03
Meso-zeaxanthin
With						4	0.13	0.05, 0.22	0.001	0.02
Without						15	0.06	0.03, 0.08	<0.001
Other antioxidants
With	7	0.08	0.04, 0.13	<0.001	0.97	3	0.10	0.05, 0.15	0.99	0.55
Without	7	0.08	0.04, 0.13	<0.001		16	0.07	0.05, 0.10	<0.001
Geographic area
Europe	9	0.08	0.04, 0.11	<0.001	0.80	8	0.06	0.03, 0.09	<0.001	0.50
Asia	3	0.10	0.05, 0.15	0.27		1	0.11	0.06, 0.16	-
USA	2	0.12	−0.15, 0.38	0.97		10	0.09	0.02, 0.15	<0.001
Methods
Objective	10	0.09	0.07, 0.12	<0.001	0.37
Psychophysical	4	0.05	−0.15, 0.24	<0.001

Abbreviations: AMD, age-related macular degeneration; CI, confidence interval; MPOD, macular pigment optical density; P_h, P for between-study heterogeneity; P_z, P for Z test; RCTs: randomized controlled trials; WMD, weighted mean differences.