title: Chick eye optics: zero to fourteen days.
abstract: Ocular dimensions and refractive state data for chicks 0 to 14 days of age were obtained from 234 untreated control eyes of birds treated unilaterally in previous work involving various defocussing lenses and/or translucent goggles. Refractive state and corneal curvatures were measured in vivo by retinoscopy and ophthalmometry respectively. Intraocular dimensions were measured by A-scan ultrasonography, after which the eyes were removed, weighed and measured. In some cases (n = 52) intraocular dimensions and lens curvatures were obtained from frozen sections of enucleated eyes. The hyperopia of hatchling chicks (+6.5 +/- 4.0 D) initially decreases rapidly and then more gradually to +2.0 +/- 0.5 D by 16 days. The distribution of refractive errors is very broad at Day 0, but becomes leptokurtotic, with a slight myopic skew, by Day 14. Corneal radius is constant for the first four days, possible as a result of pre-hatching lid pressure, and then increases linearly, as do all lens dimensions, axial diameter and equatorial diameter. Schematic eyes were developed for Days 0, 7, and 14.
authors.affiliation: Department of Ophthalmology, University of Toronto, Ontario, Canada.
authors.forename: E L
authors.initials: EL
authors.lastname: Irving
authors.forename: J G
authors.initials: JG
authors.lastname: Sivak
authors.forename: T A
authors.initials: TA
authors.lastname: Curry
authors.forename: M G
authors.initials: MG
authors.lastname: Callender
mesh_terms: D000818:Animals; D002645:Chickens / Q000502:physiology*; D003315:Cornea / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D005123:Eye / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000254:growth & development*; D007908:Lens, Crystalline / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000503:physiopathology; D014463:Ultrasonography