Table 1. Characteristics of included trials.
| Study | Country | Study design | Trial duration | Participant characteristics | Intervention | Age (years) | Diagnosis criteria of AMD | Determination method of serum lutein/MPOD |
|---|---|---|---|---|---|---|---|---|
| Studies regarding AMD and blood lutein levels | ||||||||
| Sanders et al. [1993] (27) | UK | Case-control study | – | 65 patients with AMD and 65 control subjects matched for age and sex | – | 66–87 | Defined as having degenerative changes that were clearly visible in both maculas | HPLC |
| Mares-Perlman et al. [1995] (32) | US | Nested case-control study | – | 167 patients with AMD and 167 controls matched with cases for age, sex, and current smoking status. | – | 43–75+ | Wisconsin Age-Related Maculopathy Grading System | HPLC |
| Koh et al. [2004] (33) | Singapore | Case-control study | – | Seven patients with early AMD and six volunteers with no retinal pathology | – | 58–81 | – | HPLC |
| Cardinault et al. [2005] (34) |
France | Case-control study | – | 37 AMD patients and 24 control subjects | – | Control: 71.0±1.5; patients: 74.7±1.2 | Clinical examination by the physician | HPLC |
| Rosenthal et al.* [2006] (35) | USA | Dose-ranging study | – | 45 participants with no AMD (n=15), large drusen (n=15), or advanced AMD (n=15) | – | 60–91 | – | HPLC |
| Studies regarding AMD and MPOD | ||||||||
| Murray et al. [2013] (20) | Netherlands | Randomized, double-blind, placebo-controlled, two-center investigation | 12 months | 73 patients with early AMD | Lutein capsules (10 mg ester) (n=36) or a placebo (n=37) were taken daily | 50–80 | According to the Rotterdam study (36,37) | Flicker-based technique (MPS9000) |
| Huang et al. [2015] (38) | China | Randomized, double-blind, placebo-controlled trial | 2 years | 108 patients with early AMD | 10 mg lutein (n=26); 20 mg lutein (n=27); 10 mg lutein + 10 mg zeaxanthin (n=27); placebo (n=28) daily |
>50 | Age-Related Eye Disease Study System | Fundus autofluorescence images |
| Ma et al. [2017] (39) | China | Randomized, double-blind, placebo-controlled trial | 48 weeks | 200 patients with early AMD | 20 mg lutein (n=100); placebo (n=100) | 50–79 | Fundus photographic severity scale (40) | Not given |
| Gao et al. [2018] (41) | China | Randomized, controlled trial | 3 months | 48 AMD patients; 52 eyes | 20 mg lutein; blank | 61.9±11.24 | Fluorescence fundus angiography and optical coherence tomography | The non-mydriatic fundus camera ZEISS Visucam 500 |
*, this study meets all the inclusion criteria. AMD, age-related macular degeneration; HPLC, high performance liquid chromatography; MPOD, macular pigment optical density.