title: The effect of various levels of stroboscopic illumination on the growth of guinea pig eyes.
abstract: BACKGROUND
  The aim was to investigate various levels of stroboscopic illumination effect on the growth of guinea pig eyes.
  
  
  METHODS
  Thirty-six two-week-old guinea pigs were randomised to one of three treatment groups (n = 12 for each). Two stroboscopic-reared groups were raised with a duty diurnal cycle of 50 per cent at a flash rate of 0.5 Hz. Illumination intensity varied between zero-to-250 lux or zero-to-500 lux during each cycle in each group, respectively. The third control group was exposed to 250 lux illumination. Refraction and biometric measurements were taken for each animal prior to and after two, four, six and eight weeks of treatment. Finally, retinal microstructure was examined.
  
  
  RESULTS
  There was significant correlation between refractive errors and axial elongation. After eight weeks of treatment, illumination with flickering light 0-250 lux caused a larger myopic shift with increased axial length than illumination of continuous 250 lux. Stroboscopic illumination with zero-to-500 lux caused a further myopic shift and longer axial length than stroboscopic illumination with zero-to-250 lux. In animals raised in flickering light of zero-to-250 lux or zero-to-500 lux for eight weeks, the outer segment disc membranes in photoreceptor layers were found deformed and detached.
  
  
  CONCLUSIONS
  Chronic exposure to low-frequency temporally modulated illumination-induced histological damage in the retina and induced exaggerated axial length elongation.
authors.affiliation: Jinshan Hospital, Fudan University, Shanghai, China; Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China. xdzhou2013@126.com.
authors.forename: Yue
authors.initials: Y
authors.lastname: Di
authors.forename: Na
authors.initials: N
authors.lastname: Lu
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Renyuan
authors.initials: R
authors.lastname: Chu
authors.forename: Xingtao
authors.initials: X
authors.lastname: Zhou
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000818:Animals; D058452:Axial Length, Eye / Q000254:growth & development* / Q000473:pathology*; D001699:Biometry / Q000379:methods; D005654:Fundus Oculi; D006168:Guinea Pigs; D008029:Lighting / Q000009:adverse effects / Q000379:methods; D010775:Photic Stimulation / Q000009:adverse effects / Q000379:methods; D012030:Refractive Errors / Q000209:etiology* / Q000473:pathology; D012031:Refractometry; D012160:Retina / Q000254:growth & development* / Q000473:pathology*; D055214:Retinal Photoreceptor Cell Outer Segment / Q000473:pathology; D049489:Stroboscopy / Q000009:adverse effects* / Q000379:methods
keywords: eye development; guinea pig; luminance; refractive state; stroboscopic illumination