Hypermetropia in dark reared chicks and the effect of lid suture

Uri Yinon*, Kenneth C. Koslowe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Two experimental groups of domestic fowl chicks were reared in darkness. One group was normal (DR) and the second had unilateral lid closure (DRC). A control group was reared in normal illumination (LR). The optical components of the eye were examined by retinoscopy, keratometry and phacometry while physical measurements were made using ultrasonography and micrometry. The DR chicks developed a significant hyperopia (+3.11 D) compared to the LR chicks (+0.65 D), attributed to a significant decrease in corneal height and lens thickness. A significant increase in the anteroposterior axis of the DR chicks tends to reduce the dark induced hyperopia. Lid closure in the DRC chicks increases the hyperopic effect by +3.07 D due to additional corneal flattening. These results reinforce our proposal of the chick eye as a model for research in the various forms of ametropia.

Original languageEnglish
Pages (from-to)999-1005
Number of pages7
JournalVision Research
Issue number6
StatePublished - 1986


  • Accommodation
  • Axial enlargement
  • Chicks
  • Corneal curvature
  • Dark rearing
  • Hyperopia
  • Lid suture
  • Refractive error


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