Abstract Background The spatial position of the lens in patients with cortical age-related cataract (CARC) is unclear. We investigated a basis for the assessment of visual quality after cataract surgery by analysing the ultrasound biomicroscopic characteristics of the biological parameters of the lens in patients with CARC. Methods In this retrospective study, 119 patients (50 males and 69 females, totalling 238 eyes) with CARC who underwent simple cataract surgery were selected. The lens thickness (LT), axial length (AL), anterior chamber depth (ACD), lens vault (LV), trabecular-iris angle (TIA), iris-lens angle (ILA), iris-lens contact distance (ILCD) were measured by A-scan ultrasound and ultrasound biomicroscopy. The corresponding lens position (LP) and relative lens position (RLP) were calculated. Results LP was greater in men than in women (P