CYP1A1 and pterygium: Subjects who were heterozygous (m1/m2) or homozygous (m2/m2) for the CYP1A1 polymorphisms appeared to experience a higher risk of pterygium than those who were homozygous for the wild-type allele (m1/m1; OR: 1.553; 95% CI: 1.07–2.290, p=0.037; Table 3).