title: Age-related changes in the anterior segment biometry during accommodation.
abstract: OBJECTIVE
  We investigated the dynamic response of human accommodative elements as a function of age during accommodation using synchronized spectral domain optical coherence tomography devices (SD-OCT).
  
  
  METHODS
  We enrolled 33 left eyes from 33 healthy subjects (age range, 20-39 years, 17 males and 16 females). Two SD-OCT devices were synchronized to simultaneously image the anterior segment through pupil and the ciliary muscle during 6.00 diopter (D) accommodation for approximately 3.7 seconds in two repeated measurements. The anterior segment parameters included the lens thickness (LT), radius of curvature of the lens anterior surface (LAC), maximum thickness of ciliary muscle (CMTMAX), and anterior length of the ciliary muscle (CMAL). A first-order exponential equation was used to fit the dynamic changes during accommodation. The age-related changes in the dynamic response and their relationship were calculated and compared.
  
  
  RESULTS
  The amplitude (r = -0.40 and 0.53 for LT and LAC, respectively) and peak velocity (r = -0.65 and 0.71 for LT and LAC, respectively) of the changes in LT and LAC significantly decreased with age (P < 0.05), whereas the parameters of the ciliary muscle remained unchanged (P > 0.05), except for the peak velocity of the CMAL (r = 0.44, P = 0.01). The difference in the time constant between the lens reshaping (LT and LAC) and CMTMAX increased with age (r = 0.46 and 0.57 for LT and LAC, respectively, P < 0.01). The changes in LT and LAC per millimeter of CMTMAX change decreased with age (r = -0.52 and -0.34, respectively, P < 0.05). The ciliary muscle forward movement correlated with the lens deformation (r = -0.35 and 0.40 for amplitude, while r = 0.36 and 0.58 for time constant, respectively, P < 0.05).
  
  
  CONCLUSIONS
  Age-related changes in the lens reshaping and ciliary muscle forward movement were found. Lens reshaping was much slower than the contraction of the ciliary muscle, especially in aging eyes, and this process required the ciliary muscle to contract more to reach a given response.
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 2School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Yilei
authors.initials: Y
authors.lastname: Shao
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 2School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Aizhu
authors.initials: A
authors.lastname: Tao
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States.
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 2School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Xinjie
authors.initials: X
authors.lastname: Mao
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 3Hangzhou First People's Hospital, Hangzhou, China.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Zhong
authors.affiliation: School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Meixiao
authors.initials: M
authors.lastname: Shen
authors.affiliation: School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Fan
authors.initials: F
authors.lastname: Lu
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 2School of Ophthalmology and Optometry, Wenzhou Medical College, Wenzhou, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States.
authors.forename: Carol L
authors.initials: CL
authors.lastname: Karp
authors.affiliation: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, United States 4Electrical and Computer Engineering, University of Miami, Miami, Florida, United States.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D000375:Aging / Q000502:physiology*; D000869:Anterior Eye Segment / Q000033:anatomy & histology* / Q000502:physiology; D001699:Biometry / Q000379:methods; D002924:Ciliary Body / Q000033:anatomy & histology; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000033:anatomy & histology; D008297:Male; D012029:Refraction, Ocular / Q000502:physiology; D041623:Tomography, Optical Coherence / Q000295:instrumentation*; D055815:Young Adult