The effect of manipulations to target contrast on emmetropization in chick

Schmid, Katrina L., Brinkworth, Darren R., Wallace, Kate M. and Hess, Robert (2006) The effect of manipulations to target contrast on emmetropization in chick. Vision Research, 46 6-7: 1099-1107. doi:10.1016/j.visres.2005.08.017


Author Schmid, Katrina L.
Brinkworth, Darren R.
Wallace, Kate M.
Hess, Robert
Title The effect of manipulations to target contrast on emmetropization in chick
Journal name Vision Research   Check publisher's open access policy
ISSN 0042-6989
Publication date 2006
Sub-type Article (original research)
DOI 10.1016/j.visres.2005.08.017
Volume 46
Issue 6-7
Start page 1099
End page 1107
Total pages 9
Editor D. M. Levi
Place of publication Oxford
Publisher Pergamon-Elsevier Science Ltd
Collection year 2006
Language eng
Subject C1
Abstract Emmetropization is dependent on visual feedback and presumably some measure of the optical and image quality of the eye. We investigated the effect of simple alterations to image contrast on eye growth and refractive development. A 1.6 cyc/deg square-wave-grating target was located at the end of a 3.3 cm cone,, imaged by a +30 D lens and applied monocularly to the eyes of 8-day-old chicks. Eleven different contrast targets were tested: 95, 67, 47.5, 33.5, 24, 17, 12, 8.5, 4.2, 2.1, and 0%. Refractive error (RE), vitreous chamber depth (VC) and axial length (AL) varied with the contrast of the image (RE diff. F-10.86 = 12.420, p < 0.0005; VC diff. F-10.86 = 8.756, p < 0.0005; AL diff. F-10.86 = 9.240, p < 0.0005). Target contrasts 4.2% and lower produced relative myopia (4.2%: RE diff = -7.48 +/- 2.26 D, p = 0.987; 2.1%: RE diff = -7.22 +/- 2.77 D, p = 0.951) of similar amount to that observed in response to a featureless 0% contrast target (RE diff = -9.11 +/- 4.68 D). For target contrast levels 47.5% and greater isometropia was maintained (95%: RE diff = 1.83 +/- 2.78 D; 67%: RE diff = 0.14 +/- 1.84 D; 47.5% RE diff = 0.25 +/- 1.82 D). Contrasts in between produced an intermediate amount of myopia (33.5%: RE diff = -2.81 +/- 1.80 D; 24%: RE diff = -3.45 +/- 1.64 D; 17%: RE diff = -3.19 +/- 1.54 D; 12%: RE diff = -4.08 +/- 3.56 D; 8.5%: RE diff = -4.09 +/- 3.60 D). We conclude that image contrast provides important visual information for the eye growth control system or that contrast must reach a threshold value for some other emmetropization signal to function. (c) 2005 Elsevier Ltd. All rights reserved.
Keyword contrast
chick
myopia
refractive error
spatial frequency
Refractive Error
Spatial Frequency
Eye Growth
Myopia
Sensitivity
Defocus
Retina
Adaptation
Existence
Pathways
Images
Acuity
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2007 Higher Education Research Data Collection
School of Biomedical Sciences Publications
 
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Citation counts: TR Web of Science Citation Count  Cited 7 times in Thomson Reuters Web of Science Article | Citations
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Created: Wed, 15 Aug 2007, 09:20:12 EST