Volume 9, Number 11, Article 4, Pages 1-18 doi:10.1167/9.11.4 http://journalofvision.org/9/11/4/ ISSN 1534-7362
Accommodative and vergence responses to conflicting blur and disparity stimuli during development
Shrikant R. Bharadwaj
Indiana University School of Optometry, Bloomington, IN, USA
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T. Rowan Candy
Indiana University School of Optometry, Bloomington, IN, USA
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Abstract

Accommodative and vergence responses of the typically developing visual system are generated using a combination of cues, including retinal blur and disparity. The developmental importance of blur and disparity cues in generating these motor responses was assessed by placing the two cues in conflict with each other. Cue-conflicts were induced by placing either −2 D lenses or 2 MA base-out prisms before both eyes of 140 subjects (2.0 months to 40.8 years) while they watched a cartoon movie binocularly at 80 cm. The frequency and amplitude of accommodation to lenses and vergence to prisms increased with age (both p < 0.001), with the vergence response (mean ± 1 SEM = 1.38 ± 0.05 MA) being slightly larger than the accommodative response (1.18 ± 0.04 D) at all ages (p = 0.007). The amplitude of these responses decreased with an increase in conflict stimuli (1 to 3 D or MA) (both p < 0.01). The coupled vergence response to −2 D lenses (0.31 ± 0.06 MA) and coupled accommodative response to 2 MA base-out prisms (0.21 ± 0.02 D) were significantly smaller than (both p < 0.001) and poorly correlated with the open-loop vergence (r = 0.12; p = 0.44) and open-loop accommodation (r = −0.08; p = 0.69), respectively. The typically developing visual system compensates for transiently induced conflicts between blur and disparity stimuli, without exhibiting a strong preference for either cue. The accuracy of this compensation decreases with an increase in amplitude of cue-conflict.

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History
Received June 17, 2009; published October 5, 2009
Citation
Bharadwaj, S. R., & Candy, T. R. (2009). Accommodative and vergence responses to conflicting blur and disparity stimuli during development. Journal of Vision, 9(11):4, 1-18, http://journalofvision.org/9/11/4/, doi:10.1167/9.11.4.
Keywords
accommodation, blur, cue-conflict, disparity, human infants, refractive error, vergence, visual development
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