title: [Magnetic resonance imaging study of effects of accommodation on human lens morphological characters].
abstract: OBJECTIVE
  To evaluate the effects of accommodation on lens morphological characters.
  
  
  METHODS
  From January 2011 to June 2011, magnetic resonance images of eyes were acquired from 30 subjects aged 20 to 24 years during accommodation and at rest. The optimal images were analyzed by Autocad 2010 to obtain the total lens cross-sectional area (CSA) and CSA of anterior and posterior portions of lens, anterior chamber depth, lens thickness, lens diameter, vitreous chamber depth and axial length during accommodation and at rest. Paired-t test was performed.
  
  
  RESULTS
  The anterior curvature radius (mm), posterior curvature radius (mm), CSA of anterior portion (mm(2)), CSA of posterior portion (mm(2)), total lens CSA (mm(2)) was (8.7 ± 0.8), (6.2 ± 0.5), (7.5 ± 2.1), (12.0 ± 2.6), (20 ± 4) during relaxed accommodation; anterior curvature radius (mm), posterior curvature radius (mm), CSA of anterior portion (mm(2)), CSA of posterior portion (mm(2)), total lens CSA (mm(2)) was (7.1 ± 1.3), (5.6 ± 0.5), (14.7 ± 2.9), (12.2 ± 2.1) and (27 ± 4) during accommodation. The total lens CSA (t = -11.556, P < 0.01) and CSA of anterior portion (t = -15.653, P < 0.01) both increased in accommodative states. The CSA of posterior portion of lens (t = -0.437, P > 0.05) under a statistically independent accommodative state. There was significant difference in the anterior chamber depth (t = 4.366, P < 0.01), lens thickness (t = -5.456, P < 0.01) and lens diameter (t = 4.597, P < 0.01) in accommodative states. There were insignificant differences both in vitreous chamber depth (t = 0.428, P > 0.05) and axial length (t = 0.418, P > 0.05) under accommodative states.
  
  
  CONCLUSIONS
  During accommodation, the anterior chamber depth decreases, lens thickness increases and diameter of lens decreases while anterior portions and total lens CSA increase. There are insignificant changes in posterior portions of lens CSA, vitreous chamber depth and axial length. The accommodative changes in CSA indicate that the anterior portion of lens may be related with the properties of anterior capsule and lens material, the position of zonular attachments and the location of fetal nucleus. Helmholtz theory is supported.
authors.affiliation: Department of Ophthalmology, Second Affiliated Hospital, Wenzhou Medical College, Wenzhou 325000, China. Email: doctorlily@hotmail.com.
authors.forename: Sui-lian
authors.initials: SL
authors.lastname: Zheng
authors.forename: Ai
authors.initials: A
authors.lastname: Zhang
authors.forename: Jian-jing
authors.initials: JJ
authors.lastname: Shi
authors.forename: Yun-xin
authors.initials: YX
authors.lastname: Zhou
mesh_terms: D000065:Accommodation, Ocular; D000328:Adult; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000033:anatomy & histology* / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D055815:Young Adult