Table 1. Characteristics of Included Studies.
| Source (country) | Study design | Population source | Population recruitment | Population characteristics | Race/ethnicity | Funding |
|---|---|---|---|---|---|---|
| Ludwig et al,9 2018 (US) | Prospective, cohort, single center | Consecutive newborns | 830 Approached, 202 recruited, and RRT conducted in 194 | 47% Female; 7% BW <2.5 kg; 61% VD | 55% White; 37% Asian; 1% Black; 7% Native Hawaiian | Grants from university, private and public foundations |
| Ma et al,10 2018 (China) | Prospective, cross-sectional, single center | Consecutive newborns approached 6 wk after birth | 1785 Approached, 481 recruited, and RRT conducted in 481 | 47% Female; 10% BW <2.5 kg; 57% VD | Not specified, but population from Beijing, where most identify as Han Chinese | Grants from hospital and public foundations |
| Mussavi et al,11 2014 (Iran) | Prospective, cross-sectional, single center | Consecutive newborns | Number approached was unclear, and RRT conducted in 255 | 45% Female; BW not reported; 43% VD | Not specified, but population from Ilam, where almost 100% identify as Middle Eastern origin | Grants from hospital |
| Sun et al,12 2016 (China) | Prospective, cross-sectional, single center | Consecutive newborns not preterm, not admitted to ICU, not with ocular deformities noticed without screening | 9985 Approached, 8497 eligible for study, 7641 gave consent, and RRT conducted in 7641 | 48% Female; mean (SD) BW, 3.4 (0.4) kg; 52% VD | Not specified, but population from Jinan, where most identify as Han Chinese | Grants from hospital and public foundations |
| Viquez and Wu,13 2020 (Costa Rica) | Prospective, cross-sectional, single center | Consecutive newborns not critically ill but who required monitoring | 71 Approached, 71 eligible and gave consent, and RRT conducted in 71 | 42% Female; mean (SD) BW, 2.9 (0.5) kg; 27% VD | Not specified, but population from San José, where population is highly diverse; most individuals identified as White, Asian, and Hispanic | No funding for the study, but travel grant from a pharmaceutical company for presentation |
Abbreviations: BW, birth weight; ICU, intensive care unit; RRT, red reflex test; VD, vaginal delivery.