Ma 2012.

Methods	Parallel group RCT Method of allocation: not described Masking: participant ‐ yes; provider ‐ yes; outcome ‐ yes Loss to follow‐up: unclearly reported but could be 1/108
Participants	Country: China Number of people randomised: 108 (eyes unknown) Number (%) of people followed up: 107 (99%) (eyes unknown) Average age (range): 69 (unknown) Percentage women: 58% Ethnic group: unknown Baseline visual acuity: 0.30 logMAR Comorbidities affecting the eye: 23% early cataracts Percentage current smokers: 6% Inclusion criteria: early AMD defined as the presence of soft drusen, presence of any retinal pigmentary abnormalities in the absence of signs of late AMD, or both), according to the AREDS classification system Exclusion criteria late AMD or other macular or choroidal disorders (e.g. macular edema, macular holes, central serous chorioretinopathy, or macular epiretinal membrane) demonstrated the presence of significant central lens opacities precluding fundus autofluorescence had an implanted intraocular lens glaucoma unstable chronic illness history of intraocular inflammation ocular trauma laser treatment for retinal diseases retina‐vitreous surgery photodynamic therapy currently taking medications affecting macular function (e.g., chloroquine or oxazepam) consumed dietary supplements containing vitamins or carotenoids within the 6 months before enrolment
Interventions	Intervention: lutein 10 mg or lutein 20 mg or lutein 10 mg and zeaxanthin 10 mg (3 groups) (daily) 80 people randomised (eyes unknown) 79 (99%) people followed up (eyes unknown) Comparator: placebo (daily) 27 people randomised (eyes unknown) 27 (100%) people followed up (eyes unknown) Duration: 12 months Similarity between intervention and comparator: unclear, placebo was not described
Outcomes	From the published paper: Primary: macular pigment optical density Secondary: best‐corrected visual acuity contrast sensitivity photorecovery time Amsler grid testing From clinical trials.gov (registered retrospectively): Primary Outcome Measures: MPOD and multifocal electroretinograms (time frame: 1 year) Secondary Outcome Measures: risk of advanced AMD. (time frame: 1 year) Follow‐up: 24 weeks and 48 weeks Eyes: unclear how many eyes included in study
Notes	Source of funding: Quote: "Supported by the National Natural Science Foundation of China (grant no.: NSFC‐30872113), Beijing, China." Declaration of interest: Quote: "The author(s) have no proprietary or commercial interest in any materials discussed in this article." Date study conducted: September 2009 to April 2012 Trial registration number: NCT01048476 (registered retrospectively) and NCT10528605 (registered retrospectively)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "The randomization sequence with stratification by baseline macular pigment optical density (MPOD) was computer generated, using a permuted block design with block size of 8."
Allocation concealment (selection bias)	Low risk	Quote: "All participants, the study investigators, and data analysts were masked to treatment assignment."
Blinding of participants and personnel (performance bias) Visual acuity	Low risk	Quote: "All participants, the study investigators, and data analysts were masked to treatment assignment." Quote: "To protect the blinding, the different capsules were indistinguishable by size, weight, or color."
Blinding of participants and personnel (performance bias) Progression AMD	Low risk	Quote: "All participants, the study investigators, and data analysts were masked to treatment assignment." Quote: "To protect the blinding, the different capsules were indistinguishable by size, weight, or color."
Blinding of outcome assessment (detection bias) Visual acuity	Low risk	Quote: "All participants, the study investigators, and data analysts were masked to treatment assignment." Quote: "To protect the blinding, the different capsules were indistinguishable by size, weight, or color."
Blinding of outcome assessment (detection bias) Progression AMD	Low risk	Quote: "All participants, the study investigators, and data analysts were masked to treatment assignment." Quote: "To protect the blinding, the different capsules were indistinguishable by size, weight, or color."
Incomplete outcome data (attrition bias) All outcomes	Low risk	Judgement comment: Only 1/108 participants apparently discontinued treatment and was excluded from the analysis. All other participants were followed up.
Selective reporting (reporting bias)	High risk	Judgement comment: Trial registered midway through recruitment. Outcome "late AMD" on trials register but not reported because: "... the present study was not powered adequately to detect a reduction in late AMD incidence". Other differences noted between publication and trials register entry ‐ see above.