Evaluation of corneal changes with accommodation in young and presbyopic populations using Pentacam High Resolution Scheimpflug system.

Background To evaluate the changes occurring in the cornea with accommodation in young and presbyopic people. Design Prospective study. Participants Twenty-three young and 15 presbyopic emmetropic volunteers. Methods The Pentacam High Resolution system was used to obtain data on the anterior eye segments of emmetropic volunteers in unaccommodated (with an accommodation stimulus of 0.0D) and accommodated (with an accommodation stimulus of 5.0D for the young volunteers and 1.0D for the presbyopic) states. Main Outcome Measures Anterior and posterior corneal axial curvature, corneal volume, corneal aberration, anterior chamber depth and anterior chamber volume were evaluated. Results A significant decline in anterior chamber depth and anterior chamber volume was induced by accommodation in both young and presbyopic volunteers. There was a small but statistically significant change in corneal volume within 3.0, 5.0 and 7.0mm diameters during accommodation in both groups. The changes in the corneal curvature map were significant with accommodation in both groups, although individual variations were found in anterior and posterior corneal axial curvature. Moreover, the decreased higher order aberrations were found in both anterior and entire cornea. In particular, spherical aberration was changed in the young group with 5.0D accommodation stimulus. Conclusion This study showed that accommodation can influence the corneal shape and curvature, and, especially, decreased corneal high-order aberrations. Although the modification in corneal shape was small, it produced variations in higher order aberrations with accommodation that may be beneficial for visual performance in near vision.