title: [Effect of ocular accommodation on refractive components in children].
abstract: OBJECTIVE
  To study the correlation between ocular accommodation and ametropia, especially myopia by analyzing the effect of accommodation on refractive components in children.
  
  
  METHODS
  The anterior chamber depth (AD), lens thickness (LT), vitreous chamber length (VL) and ocular axial length (AL) were measured for 135 cases (270 eyes) of children before and after cycloplegia. The corneal shapes of 136 eyes selected from the 270 eyes were studied before and after cycloplegia by a computerized video keratoscope.
  
  
  RESULTS
  AD increased (P < 0. 001) while both LT (P < 0. 001) and VL decreased (P < 0. 01) significantly after cycloplegia regardless of their refractive state. However, AL increased for hyperopic eyes (P = 0.027) and decreased for myopic eyes (P = 0.008) after cycloplegia. For hyperopic eyes, the major keratometer K1 increased (P = 0.025) while for myopic eyes, the major keratometer K1 (P = 0.039) and minor keratometer K2 (P = 0.003) decreased after cycloplegia. Similarly, mean corneal power of zones 3 mm (MD3), 5 mm (MD5) and 7 mm (MD7) decreased dramatically (P < 0.05) with myopic eyes after cycloplegia, while MD3 (P = 0.009) increased with hyperopic eyes. The mean refractive power of the lower half vertical meridian (LMD) is greater than that of upper half (UMD); and the mean refractive power of the lateral half of the horizontal (LaMD) is greater than that of the medial half (MMD).
  
  
  CONCLUSIONS
  The ocular accommodation has a great influence on refractive components in children. It is not only the process by which the refractive power of the lens is increased. Furthermore, the lens itself moved forward relatively. There is asymmetry of the corneal surface within the same horizontal or vertical meridian.
authors.affiliation: Department of Ophthalmology, Yantai Yuhuangding Hospital, Affiliated Hospital of Medical College, Qingdao University, Yantai 264000, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Gao
authors.forename: Jinghua
authors.initials: J
authors.lastname: Wang
authors.forename: Xuying
authors.initials: X
authors.lastname: Zhuo
authors.forename: Ning
authors.initials: N
authors.lastname: Yu
authors.forename: Lusheng
authors.initials: L
authors.lastname: Ma
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D002648:Child; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology*; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000503:physiopathology*