| All ages | No. | Grade 1 pterygia (transparent) | Grade 2 pterygia (intermediate) | Grade 3 pterygia (opaque) | |||
| N/prevalence/95% CI | N/prevalence/95% CI | N/prevalence/95% CI | |||||
| Study design adjusted rate | 2076 | 49 | 1.3 (0.7 to 2.0) | 119 | 8.7 (6.6 to 10.8) | 112 | 3.9 (2.4 to 5.6) |
| Age (years) | |||||||
| 40 to 49 | 664 | 18 | 2.7 (1.6 to 4.3) | 25 | 3.8 (2.5 to 5.5) | 34 | 5.1 (3.6 to 7.1) |
| 50 to 59 | 603 | 14 | 2.3 (1.3 to 3.9) | 39 | 6.5 (4.6 to 8.7) | 32 | 5.3 (3.7 to 7.4) |
| 60 to 69 | 439 | 6 | 1.4 (0.5 to 2.9) | 38 | 8.7 (6.2 to 11.7) | 23 | 5.2 (3.4 to 7.8) |
| 70+ | 370 | 11 | 2.9 (1.5 to 5.3) | 17 | 4.6 (2.7 to 7.3) | 23 | 6.2 (3.9 to 9.2) |
| p (trend) | = 0.06 | = 0.06 | = 0.06 | ||||
| Gender | |||||||
| Male | 836 | 17 | 2.0 (1.2 to 3.2) | 49 | 5.9 (4.4 to 7.7) | 33 | 3.9 (2.7 to 5.5) |
| Female | 1240 | 32 | 2.3 (1.8 to 3.2) | 70 | 5.6 (4.4 to 7.1) | 79 | 6.4 (5.1 to 7.9) |
| p value | = 0.1 | = 0.1 | = 0.1 | ||||
| Work | |||||||
| Primarily outdoor | 1404 | 34 | 2.4 (1.7 to 3.4) | 85 | 6.6 (4.9 to 7.4) | 94 | 6.7 (5.5 to 8.1) |
| Primarily indoor | 672 | 15 | 2.2 (1.3 to 3.7) | 34 | 5.1 (3.5 to 7.0) | 18 | 2.7 (1.6 to 4.2) |
| p value | 0.001 | 0.001 | 0.001 | ||||
CI, confidence interval; N, number.