title: Comparison of form-deprived myopia and lens-induced myopia in guinea pigs.
abstract: OBJECTIVE
  To study the efficacy difference between form-deprived myopia (FDM) and lens-induced myopia (LIM), the degree of myopia, axial length and pathological changes of the posterior sclera from guinea pigs were evaluated.
  
  
  METHODS
  Four-week pigmented guinea pigs were randomly assigned into 3 groups, including normal control (n=6), FDM group with monocular cover (n=11) and LIM group with monocular -7D lens treatment (n=11). FDM group was form-deprived while LIM group was lens-induced for 14 d. Refractive error and axial length were measured prior to and post treatment, respectively. Morphological changes of sclera were examined using both light and electronic microscopes.
  
  
  RESULTS
  After 14d treatment, refractive errors for FDM group and LIM group were -3.05±0.71D and -2.12±1.29D, respectively, which were significantly more myopic than that of normal controls and fellow control eyes (P<0.01). As for axial length, it was 7.93±0.03 mm for FDM group and 7.89±0.06 mm for LIM group, which were significantly longer than both normal and fellow controls (P<0.01). With respect to both refractory error and axial length, the differences between FDM group and LIM group were not significant (P>0.05). Under light microscope, both FDM group and LIM group showed thinned sclera, disarrangement of fibrosis and enlarged disassociation between fibers. Consistently, ultrastructural examination showed degenerated fibroblasts and thinned fibers in posterior sclera.
  
  
  CONCLUSIONS
  Following two weeks of myopia induction in guinea pigs, with regard to the degree of myopia, axial length and pathological alterations, there was no significant difference between FDM and LIM models. Therefore, FDM and LIM are equally effective and useful as a model of experimental myopia and guinea pigs are ideal animals for induction of experimental myopia because their high sensitivity to both form-deprivation and lens-induction.
authors.affiliation: Department of Ophthalmology, the First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China ; Department of Ophthalmology, the 463th Hospital of the People's Liberation Army, Shenyang 110042, Liaoning Province, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xiao
authors.affiliation: Department of Ophthalmology, the 463th Hospital of the People's Liberation Army, Shenyang 110042, Liaoning Province, China.
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Fan
authors.affiliation: Department of Ophthalmology, the Fourth People's Hospital of Shenyang, Shenyang 110000, Liaoning Province, China.
authors.forename: Xiao-Dan
authors.initials: XD
authors.lastname: Tian
authors.affiliation: Department of Ophthalmology, the First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning Province, China.
authors.forename: Yan-Chun
authors.initials: YC
authors.lastname: Xu
keywords: form-deprived myopia; lens-induced myopia; pathology