کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9348621 | 1263608 | 2005 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Ocular compensation for alternating myopic and hyperopic defocus
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موضوعات مرتبط
علوم زیستی و بیوفناوری
علم عصب شناسی
سیستم های حسی
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چکیده انگلیسی
During development, the eye grows under visual feedback control, as shown by its compensating for defocus imposed by spectacle lenses. Under normal conditions the sign and magnitude of defocus vary with viewing distance, accommodative status and other factors. To explore how periods of myopic and hyperopic defocus are integrated over time we presented rapidly alternating episodes of myopic and hyperopic defocus by sequentially illuminating a nearby scrim and the wall beyond it to chick eyes wearing lenses that put the far point between the two surfaces. We found that equal periods of myopic and hyperopic defocus generally led to compensatory hyperopia, showing that myopic defocus had a disproportionate effect. Furthermore, the degree of hyperopia depended on the frequency of alternation: low frequencies (1Â cycle/30Â min) resulted in more hyperopia, whereas at high frequencies (1Â cycle/s) the myopic and hyperopic defocus nearly cancelled each other. If similar temporal integration effects apply to humans, they may help explain why brief accommodation events may not influence lens-compensation and why a child's total reading time may be a poor predictor of myopic progression.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Vision Research - Volume 45, Issue 13, June 2005, Pages 1667-1677
Journal: Vision Research - Volume 45, Issue 13, June 2005, Pages 1667-1677
نویسندگان
Jonathan Winawer, Xiaoying Zhu, John Choi, Josh Wallman,