Purpose. To visualize and assess in vivo the age-related changes in crystalline lens size and contour. Methods. Seventy-nine healthy volunteers, 39 females and 40 males, with a mean age of 41.53 + 11.32 years (range: 21 to 60 years) were enrolled in this study. The axial lens thickness (ALT), equatorial lens diameter (ELD), and anterior (Ra) and posterior (Rp) lens surface radii of curvatures of the subjects’ left eyes were measured with a 25 MHz ultrasound probe. Results. The mean ALT and ELD were 4.178 mm + 0.288 mm and 9.209 mm + 0.214 mm, respectively. There was a statistically significant increase in both ALT (slope = 11 μm/year, r = 0.88, p