title: Does transient increase in axial length during accommodation attenuate with age?
abstract: BACKGROUND
  The aim was to profile transient accommodative axial length changes from early adulthood to advanced presbyopia and to determine whether any differences exist between the responses of myopic and emmetropic individuals.
  
  
  METHODS
  Ocular biometry was measured by the LenStar biometer (Haag-Streit, Switzerland) in response to zero, 3.00 and 4.50 D accommodative stimuli in 35 emmetropes and 37 myopes, aged 18 to 60 years. All results were corrected to reduce errors arising from the increase in crystalline lens thickness with accommodation. Accommodative responses were measured sequentially by the WAM 5500 Auto Ref/Keratometer (Grand Seiko, Hiroshima, Japan).
  
  
  RESULTS
  Axial length increased significantly with accommodation (p < 0.001), with a mean corrected increase in axial length of 2 ± 18 µm and 8 ± 16 µm observed at 3.00 and 4.50 D, respectively. The magnitude of accommodative change in axial length was not dependent on refractive error classification (p = 0.959); however, a significant reduction in the magnitude and variance of axial length change was evident after 43 to 44 years of age (p < 0.002).
  
  
  CONCLUSIONS
  The negative association between transient increase in axial length and age, in combination with reduced variance of data after age 43 to 44 years, is consistent with a significant increase in posterior ocular rigidity, which may be influential in the development of presbyopia.
authors.affiliation: Ophthalmic Research Group, Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: Deborah S
authors.initials: DS
authors.lastname: Laughton
authors.affiliation: Ophthalmic Research Group, Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Sheppard
authors.affiliation: School of Optometry and Vision Science, University of Bradford, Bradford, UK.
authors.forename: Edward A H
authors.initials: EAH
authors.lastname: Mallen
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Park, Queensland, Australia.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Read
authors.affiliation: Ophthalmic Research Group, Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: Leon N
authors.initials: LN
authors.lastname: Davies
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D058452:Axial Length, Eye / Q000502:physiology*; D001699:Biometry; D058453:Emmetropia / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology*; D011305:Presbyopia / Q000503:physiopathology*; D055815:Young Adult
keywords: accommodation; axial length; biometry; crystalline lens; presbyopia