Effects on the compensatory responses to positive and negative lenses of intermittent lens wear and ciliary nerve section in chicks.
This study examined the ocular compensation to lens-induced defocus in chick and the effect of interrupting lens wear on a daily basis. Eyes fitted with +10 D lenses at hatching compensated rapidly, with almost complete compensation after 4 days of lens wear; they had decreased vitreous chamber depth compared to normal eyes and were thus hyperopic when the lenses were removed. In contrast, adaptation to the -10 D lenses was much slower, was still incomplete after 9 days of lens wear, and in this case, eyes had increased vitreous chamber depth and were myopic without the lenses. Adaptation improved when lens wear was delayed until 7 days after hatching. The effect of interrupting lens wear by periods of normal vision varied with the sign of the lenses worn. Hyperopia was always seen in response to +10 D lenses, although the magnitude of the response decreased as the duration of lens wear was decreased. In contrast, even brief periods of normal vision, i.e., 3 hr, prevented the development of myopia in response to the -10 D lenses; this apparent sensitivity to normal vision is similar to that reported for form-deprivation myopia. Ciliary nerve section used here to eliminate accommodation did not alter these response patterns.
Schmid
K L
KL
Centre for Eye Research, Queensland University of Technology and Vision, Brisbane, Australia. K.Schmid@qut.edu.au
Wildsoet
C F
CF
D000065:Accommodation, Ocular; D000704:Analysis of Variance; D000818:Animals; D002645:Chickens / Q000502:physiology*; D002924:Ciliary Body / Q000601:surgery; D003261:Contact Lenses; D006956:Hyperopia / Q000473:pathology / Q000503:physiopathology; D008297:Male; D009216:Myopia / Q000473:pathology / Q000503:physiopathology; D012030:Refractive Errors / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors; D014822:Vitreous Body / Q000254:growth & development* / Q000473:pathology