Monocular accommodation response to random defocus changes induced by a tuneable lens
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|Title:||Monocular accommodation response to random defocus changes induced by a tuneable lens||Authors:||Sharmin, Najnin; Vohnsen, Brian||Permanent link:||http://hdl.handle.net/10197/11295||Date:||Dec-2019||Online since:||2020-03-05T13:16:19Z||Abstract:||Accommodation of the human eye relies on multiple factors and visual cues that include object size, monochromatic and chromatic aberrations, and vergence. Yet, even in monocular conditions, accommodation corrects for defocus. Studies of eye growth in chicks have addressed whether the retina can decode the sign of defocus as this may play a role for emmetropization and possibly also accommodation. However, findings have not been unambiguous and questions remain. Here, we report on monocular accommodation studies of emmetropic and myopic human subjects to clarify whether foveal vision drives accommodation in the correct direction by removing out-of-focus blur potentially before relying on other cues. Subjects viewed monocularly a green target at 1-meter distance while being presented with a random sequence of negative defocus step changes induced by a pupil-conjugated currentdriven tuneable lens. The natural pupil was constricted by a pupil-conjugated motorized iris using three different diameters and target brightness was set with a liquid crystal variable attenuator. A Hartmann-Shack wavefront sensor with an infrared beacon captured real-time changes of defocus and Zernike polynomial coefficients up to 4th radial order. We find that the young adult eye accommodates reliably in the correct direction but with a latency of 300 – 700 ms. The findings are discussed in relation to an absorption model of light in outer segments 2 that breaks the defocus symmetry and thus may serve as a plausible guide for accommodation and emmetropization.||Funding Details:||European Commission Horizon 2020||Type of material:||Journal Article||Publisher:||Elsevier||Journal:||Vision Research||Volume:||165||Start page:||45||End page:||53||Copyright (published version):||2019 Elsevier||Keywords:||Accomodation; Defocus; Eye model; Retina model; Geometrical optics||DOI:||10.1016/j.visres.2019.10.002||Language:||en||Status of Item:||Peer reviewed|
|Appears in Collections:||Physics Research Collection|
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