CYP46A1 and glaucoma: Genotype distribution and allele frequency of the CYP46A1 IVS2 –150 C>T polymorphism (rs754203) in patients with primary open angle glaucoma (POAG) with early (mean defect [MD] above −6 dB), moderate (MD between −6 and −12 dB) and severe (MD below −12dB) defect.