Purpose To quantify the biometric changes of ocular dimensions with mechanical elevation of intraocular pressure (IOP) in vivo, to get a better understanding of the elastic properties of the human ocular structures that may play a role in the pathogenesis of various diseases such as myopia or glaucoma. Methods Changes in IOP were induced by a suction cup in 18 eyes under cycloplegia. Axial eye length (AEL) and anterior chamber depth (ACD) were measured with non-invasive laser interferometry during elevation of the IOP 10 and 20 mmHg over baseline values and after a 10-min resting period. Results IOP elevation of 10 and 20 mmHg respectively caused a significant increase of AEL of 23 lm (95% confidence interval: 14-34 lm) and 39 lm (confidence interval (CI): 28-51 lm). After mechanical oculopression, which resulted in an IOP reduction of -5.1 mmHg (CI: À6.3 to À4.0 mmHg) vs baseline, a significant shortening of À7 lm (CI: À13 to 0 lm) was observed. The change in AEL correlated with the change in IOP (r ¼ 0.66, P ¼ 0.005). Furthermore, a significant increase in ACD of 30 lm (CI: 24-36 lm) was detected with IOP reduction after oculopression, but no change was seen during IOP elevation. Conclusions Biometric changes of the human eye as a response to IOP changes were assessed in vivo. The correlation between change in AEL and IOP found emphasizes the need of in vivo ocular rigidity measurements in the human eye.