December 2013
Volume 13, Issue 15
OSA Fall Vision Meeting Abstract  |   October 2013
Optical basis of polyplopia
Author Notes
  • Footnotes
     Moderator: Heidi Hofer, University of Houston
  • Footnotes
     Blur has long been regarded as a necessary evil, something that we are stuck with as a result of the laws of optics. But with regards to blur, the visual system again shows its facility to turn lemons into lemonade by adapting away some of the perceptual effects of blur and exploiting blur as a cue to depth. This symposium examines the visual mechanisms involved in the detection and discrimination of defocus and higher-order aberrations, along with the subsequent processing of these signals.
Journal of Vision October 2013, Vol.13, T1. doi:
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      Arthur Bradley, Renfeng Xu, Larry Thibos; Optical basis of polyplopia. Journal of Vision 2013;13(15):T1. doi:

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

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Purpose: Although low pass filtering is generally the most obvious effect of defocus, defocus combined with certain higher order aberrations can generate multiple images, referred to as monocular diplopia, triplopia, or more generally polyplopia. Previous investigators have attributed polyplopia to segmented optics, multifocal optics, aberrations or diffraction.

Methods: Employing Wavefront Error (WFE) maps generated by specific Zernike vectors, we examine the impact of both higher order aberrations and diffraction on image structure, and identify the optical conditions that generate wavefronts consistent with image doubling, triple images and quadrupled images.

Results: When WFEs introduced by HOAs are combined with opposite sign defocus, approximately plane waves can be generated locally within specific regions of the pupil each with different average wavefront slopes. The number of such plane wavefront regions determine the number of multiple images. The size of each region determines image contrast and the difference in average slope determines the spatial off-set of each image. When wavefronts are modulated 2, 3, or 4 times around the pupil e.g. by astigmatism, trefoil or quadrafoil, combinations of opposite sign defocus and spherical aberration generate two, three and four flat regions within the wavefront, and thus 2, 3 or 4 images.

Conclusions: Segmented focused optics and defocused aberrated optics can both generate wavefronts with approximately plane regions that have different average slopes, which produce multiple images. Modulations within the defocused PSF generated by diffraction are on a much smaller scale, and likely to be less visible.


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