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Journal of Biomedical Optics

Automated detection of ocular focus
Author(s): David G. Hunter; Kevin J. Nusz; Nainesh K. Gandhi; Imran H. Quraishi; Boris I. Gramatikov; David L. Guyton
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Paper Abstract

We characterize objectively the state of focus of the human eye, utilizing a bull's eye photodetector to detect the double-pass blur produced from a point source of light. A point fixation source of light illuminates the eye. Fundus-reflected light is focused by the optical system of the eye onto a bull's eye photodetector [consisting of an annulus (A) and a center (C) of approximately equal active area]. To generate focus curves, C/A is measured with a range of trial lenses in the light path. Three human eyes and a model eye are studied. In the model eye, the focus curve showed a sharp peak with a full width at half maximum (FWHM) of ±0.25 D. In human eyes, the ratio C/A was >4 at best focus in all cases, with a FWHM of ±1 D. The optical apparatus detects ocular focus (as opposed to refractive error) in real time. A device that can assess focus rapidly and objectively will make it possible to perform low-cost, mass screening for focusing problems such as may exist in children at risk for amblyopia.

Paper Details

Date Published: 1 September 2004
PDF: 7 pages
J. Biomed. Opt. 9(5) doi: 10.1117/1.1781669
Published in: Journal of Biomedical Optics Volume 9, Issue 5
Show Author Affiliations
David G. Hunter, Children's Hospital Boston (United States)
Kevin J. Nusz, Johns Hopkins Univ. (United States)
Nainesh K. Gandhi, Johns Hopkins Univ. (United States)
Imran H. Quraishi, Johns Hopkins Univ. (United States)
Boris I. Gramatikov, Johns Hopkins Univ (United States)
David L. Guyton, Johns Hopkins Univ. (United States)

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