title: Three-dimensional magnetic resonance imaging of the phakic crystalline lens during accommodation.
abstract: OBJECTIVE
  To quantify changes in crystalline lens curvature, thickness, equatorial diameter, surface area, and volume during accommodation using a novel two-dimensional magnetic resonance imaging (MRI) paradigm to generate a complete three-dimensional crystalline lens surface model.
  
  
  METHODS
  Nineteen volunteers, aged 19 to 30 years, were recruited. T(2)-weighted MRIs, optimized to show fluid-filled chambers of the eye, were acquired using an eight-channel radio frequency head coil. Twenty-four oblique-axial slices of 0.8 mm thickness, with no interslice gaps, were acquired to visualize the crystalline lens. Three Maltese cross-type accommodative stimuli (at 0.17, 4.0, and 8.0 D) were presented randomly to the subjects in the MRI to examine lenticular changes with accommodation. MRIs were analyzed to generate a three-dimensional surface model.
  
  
  RESULTS
  During accommodation, mean crystalline lens thickness increased (F = 33.39, P < 0.001), whereas lens equatorial diameter (F = 24.00, P < 0.001) and surface radii both decreased (anterior surface, F = 21.78, P < 0.001; posterior surface, F = 13.81, P < 0.001). Over the same stimulus range, mean crystalline lens surface area decreased (F = 7.04, P < 0.005) with a corresponding increase in lens volume (F = 6.06, P = 0.005). These biometric changes represent a 1.82% decrease and 2.30% increase in crystalline lens surface area and volume, respectively. CONCLUSIONS; The results indicate that the capsular bag undergoes elastic deformation during accommodation, causing reduced surface area, and the observed volumetric changes oppose the theory that the lens is incompressible.
authors.affiliation: Ophthalmic Research Group, Life and Health Sciences, Aston University, Birmingham, United Kingdom.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Sheppard
authors.forename: C John
authors.initials: CJ
authors.lastname: Evans
authors.forename: Krish D
authors.initials: KD
authors.lastname: Singh
authors.forename: James S
authors.initials: JS
authors.lastname: Wolffsohn
authors.forename: Mark C M
authors.initials: MC
authors.lastname: Dunne
authors.forename: Leon N
authors.initials: LN
authors.lastname: Davies
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000328:Adult; D001699:Biometry; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007908:Lens, Crystalline / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008954:Models, Biological; D015203:Reproducibility of Results; D055815:Young Adult