In the current cell-based study, therefore, we examine the dual activity of CYP1B1 (retinol and 17β-estradiol metabolism) using natural mutations occurring in glaucoma patients, and we attempt to correlate the differential activity of the enzyme with the clinical phenotypes of the patients (PCG vs POAG) carrying those mutations. This evidence concerns the gene CYP1B1 and open-angle glaucoma.