Table 1. Characteristics of eligible studies included in the meta-analysis.
| First author | Year | Country | Ethnicity | Study design | Criteria for DM | Criteria for DR | Polys | Cases | Controls | ||||
| Subjects (women) | Age range (mean ± SD) | Grade of DR | Subjects (women) | Age range (mean ± SD) | Type | ||||||||
| Beránek M [7] | 2002 | Czech | Caucasian | C-C | WHO | ETDRS | −988C/A,  −800G/A, −509C/T, +869T/C(L10P)(L10P), +915G/C(R25P) |
73(36) | 48–79(62.9±8.1) | PDR | 172(92) | 24–90(62.6±12.1) | NIDDM |
| Buraczynska M [8] | 2007 | Poland | Caucasian | C-C | WHO | ETDRS | −509C/T, +869T/C(L10P), −396G/C | 195(92) | N/A(58.6±9.4) | Any DR | 168(87) | N/A(55.3±7.9) | Type 2 DM |
| Paine SK [9] | 2012 | India | Indian | C-C | WHO | ETDRS | −509C/T | 253(120) | N/A(52±15.0) | PDR | 240(112) | N/A(54±12.0) | Type 2 DM |
Abbreviations: NIDDM: non-insulin-dependent diabetes mellitus. DM: diabetes mellitus. C-C: Case-control. PDR: proliferative diabetic retinopathy. DR: diabetic retinopathy. WHO: World Health Organization guidelines. ETDRS: the Early Treatment Diabetic Retinopathy Study. Polys: genotype combinations of polymorphisms. N/A: Not applicable.