title: Evaluation of corneal changes with accommodation in young and presbyopic populations using Pentacam High Resolution Scheimpflug system.
abstract: BACKGROUND
  To evaluate the changes occurring in the cornea with accommodation in young and presbyopic people.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  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 0.0 D) and accommodated (with an accommodation stimulus of 5.0 D for the young volunteers and 1.0 D for the presbyopic) states.
  
  
  METHODS
  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 7.0 mm 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 5.0 D accommodation stimulus.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Zhongshan Ophthalmic Center, State Key Laboratory of Ophthalmology, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Ni
authors.forename: Xialin
authors.initials: X
authors.lastname: Liu
authors.forename: Ying
authors.initials: Y
authors.lastname: Lin
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Guo
authors.forename: Xueqin
authors.initials: X
authors.lastname: Wang
authors.forename: Yizhi
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000867:Anterior Chamber / Q000503:physiopathology; D003315:Cornea / Q000503:physiopathology*; D058453:Emmetropia / Q000502:physiology*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010781:Photography / Q000295:instrumentation; D011305:Presbyopia / Q000503:physiopathology*; D011446:Prospective Studies; D055815:Young Adult