Abstract / Summary
AbstractPurpose: To evaluate anterior segment changes induced by the Valsalva maneuver in phakic and pseudophakic eyes using Scheimpflug imaging.Materials and methods: This paired-eye cross-sectional observational study included 136 eyes of 68 patients with unilateral pseudophakia, with each participant contributing one pseudophakic eye and the contralateral phakic eye. Intraocular pressure (IOP), central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV), pupil diameter (PD), iridocorneal angle (ICA), axial length (AL), and the ACD/AL ratio were measured at baseline and during a standardized Valsalva maneuver. Measurements were obtained using non-contact tonometry, Scheimpflug imaging, and optical biometry. Within-eye changes from baseline were analyzed separately for phakic and pseudophakic eyes.Results: During the Valsalva maneuver, IOP and PD increased significantly in both phakic and pseudophakic eyes (all p≤0.003). In phakic eyes, ACD and ACV decreased significantly (both p=0.03), whereas ICA did not change significantly (p=0.58). In pseudophakic eyes, ICA decreased significantly (p=0.002), whereas the changes in ACD and ACV were not statistically significant (p=0.08 and p=0.61, respectively). No statistically significant changes were detected in AL, CV, or the ACD/AL ratio in either group. CCT changes did not reach the predefined threshold for statistical significance.Conclusions: The Valsalva maneuver was associated with transient changes in intraocular pressure, pupil diameter, and selected anterior segment parameters in both phakic and pseudophakic eyes. Within-eye analyses showed significant reductions in ACD and ACV in phakic eyes and significant narrowing of the ICA in pseudophakic eyes. However, direct comparison of these changes between lens-status groups is required before concluding that phakic and pseudophakic eyes exhibit different biomechanical responses. Standardization of respiratory effort may improve the reliability of anterior segment imaging and biometric measurements.