McNemar test to compare the CM status of age-matched, sex-matched and postcode-matched pairs
| Controls | McNemar | |||
| Pterygium cases | With CM (n (%)) | No CM (n (%)) | Total | p |
| With CM | 53 (0.2) | 1030 (4.4) | 1083 | |
| No CM | 821 (3.5) | 21 721 (91.9) | 22 542 | |
| Total | 874 | 22 751 | 23 625 | <0.000 |
CM, cutaneous melanoma.