Influence of Controlled Viewing Conditions on Emmetropization to Imposed Myopic Defocus in the Chick

Wildsoet, Christine F., Nevin, Simon T., & Schmid, Katrina L. (2000) Influence of Controlled Viewing Conditions on Emmetropization to Imposed Myopic Defocus in the Chick. In Myopia Updates II. Proceedings of the 7th International Conference on Myopia, Sringer, pp. 113-118.


What cues are used in active emmetropization to analyse retinal image defocus remain unresolved. We asked two related questions: How important is sharp vision for compensation for myopic defocus? How fixed is the end-point of emmetropization? Chicks were fitted with monocular +40 D lenses with: 1) white translucent open cones attached, to limit (2.5 cm cone) or preclude (5 cm cone) sharp vision; 2) 2.5 cm cones closed with a blank white translucent screen or one with a black Maltese cross target (MX) added. “No cone‿ and “no lens‿ conditions were also included. Refractive error and vitreous chamber depth were measured. Partial compensation (hyperopia) occurred with the +40 D lens alone or combined with the 2.5 cm cone but was replaced by myopia with the 5 cm cone attached. The blank screen condition induced myopia, both with and without the +40 D lens, presumably due to form deprivation. Eyes were approximately emmetropic for the +40 D lens-MX cross condition. Together these data suggest that some access to sharp vision is necessary for compensation to imposed myopia. Furthermore, when visual information is confined to one plane and relative distance information is also restricted, the emmetropization end-point shifts in accord with the incident vergence at the eye.

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ID Code: 4191
Item Type: Conference Paper
Refereed: Yes
Additional Information: For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: Dr Christine Wildsoet
Additional URLs:
Keywords: myopia, emmetropization, blur, defocus, chick
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2000 Springer
Copyright Statement: This is the author-version of the work. Conference proceedings published, by Springer Verlag, will be available via SpringerLink.
Deposited On: 15 Jun 2006 00:00
Last Modified: 15 Jan 2009 07:04

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