June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
There is more to accommodation than simply maximizing retinal image contrast
Author Affiliations & Notes
  • Philip B Kruger
    State College of Optometry, State University of New York, New York, New York, United States
    Faculty of Optics and Optometry, University of Murcia, Murcia, Spain
  • Ivan Marín-Franch
    Department of Optics and Optometry and Visual Sciences, University of Valencia, Valencia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Antonio J. Del Águila-Carrasco
    Department of Optics and Optometry and Visual Sciences, University of Valencia, Valencia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Paula Bernal-Molina
    Department of Optics and Optometry and Visual Sciences, University of Valencia, Valencia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Jose Esteve-Taboada
    Department of Optics and Optometry and Visual Sciences, University of Valencia, Valencia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Robert Montés-Micó
    Department of Optics and Optometry and Visual Sciences, University of Valencia, Valencia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Norberto Lopez-Gil
    Faculty of Optics and Optometry, University of Murcia, Murcia, Spain
    Interuniversity Laboratory for Research in Vision and Optometry, Mixed group, UVEG-UMU, Valencia-Murcia, Spain
  • Footnotes
    Commercial Relationships   Philip Kruger, None; Ivan Marín-Franch, None; Antonio J. Del Águila-Carrasco, None; Paula Bernal-Molina, None; Jose Esteve-Taboada, None; Robert Montés-Micó, None; Norberto Lopez-Gil, None
  • Footnotes
    Support  European Research Council grant ERC-2012-StG-309416-SACCO
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 2057. doi:
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    • Get Citation

      Philip B Kruger, Ivan Marín-Franch, Antonio J. Del Águila-Carrasco, Paula Bernal-Molina, Jose Esteve-Taboada, Robert Montés-Micó, Norberto Lopez-Gil; There is more to accommodation than simply maximizing retinal image contrast. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2057.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : We tested the hypothesis that accommodation operates as a contrast-maximizing negative feedback system.

Methods : Two experimental conditions were tested to determine whether blur of a target alone is what drives accommodation. In the first condition the subject viewed a target (monochromatic Maltese cross subtending 2° on a micro-display through a 4-mm artificial pupil) that was always imaged accurately on the retina while the Maltese cross itself was blurred by an amount that depended on the subject’s accommodative error (lead or lag). Thus the subject was rewarded with a less blurred target for correct accommodation, but punished by a blurrier target for incorrect accommodation. No vergence changes were present because the blurred target was always in focus on the retina. In the second condition, the target itself was always a clear Maltese cross, but the retinal image of the target was blurred by the subject’s accommodative error; thus changes in accommodation provided normal feedback from defocus blur. Three experiments were performed on nine subjects (ages 21-40) using these two conditions. In the first a stationary target was presented for 50 sec at −2D; in the second, the target stepped randomly from −2D to −1D or −3D during 50-sec trials; in the third, the target moved sinusoidally between −3D & −1D at 0.05, 0.1, 0.2 or 0.4 Hz. In all three experiments, astigmatism & higher-order aberrations were recorded & corrected with adaptive optics at 20 Hz.

Results : Accommodative error was similar for the 2 conditions for stationary targets, but standard deviations of accommodative responses were significantly smaller when there was feedback from vergence (second condition). Dynamic accommodative gain in the step & sinusoidal motion experiments was significantly greater when there was feedback from vergence. The figure is an example of results averaged over 6 trials for all 9 subjects at 0.2 Hz for the two conditions in the third experiment.

Conclusions : The visual system detects the sign of optical vergence even without monocular or optical cues. Recent models based on Stiles-Crawford effect & retinal blood vessels may explain how the eye extracts the sign & magnitude of defocus (Vohnsen, Biomed. Opt. Express 5,5, 1569, 2014; Lopez-Gil et al, ARVO 2016). Understanding these mechanisms of inferring optical vergence by retinal cone signals may help explain emmetropization & define new treatments for myopia control.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

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