Forward light scatter analysis of the eye in a spatially-resolved double-pass optical system.
Bottom Line: An optical analysis is developed to separate forward light scatter of the human eye from the conventional wavefront aberrations in a double pass optical system.We prove an additivity property for radial variance that allows us to distinguish between spot blurs from macro-aberrations and micro-aberrations.When the method is applied to tear break-up in the human eye, we find that micro-aberrations in the second pass accounts for about 87% of the double pass image blur in the Shack-Hartmann wavefront aberrometer under our experimental conditions.
Affiliation: School of Optometry, Indiana University, 800 Atwater Avenue, Bloomington, Indiana 47405, USA. firstname.lastname@example.orgShow MeSH
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Mentions: In this section, we test the assertion that radial variances of object and PSF can be added together to produce the radial variance of the image by using the concept of a localized Gaussian disturbance of the wavefront. This validation is placed in the context of tear film breakup by modeling the localized thinning of the tear film as an application of a small drop of dryness called a “xerop” (from the Greek word xeros (ξερός) for “dry”) to the tear layer. The result is a localized shortening of the optical path length from retina to SH wavefront sensor that perturbs the wavefront aberration function. For demonstration purposes, we assume this perturbation is small enough to fit inside a lenslet face. For simplicity, we choose a Gaussian xerop,W(x,y)=Cexp[−x2+y22σ2].(14)In the first pass, a narrow beam of light goes through the pupil center when tear film is smooth. This first pass optical system is assumed to be diffraction limited in our validation test case. This diffraction-limited retinal image from the first pass becomes an object for the second pass. Light passing through a xerop on this second pass forms a blurred image in the SH image (Fig. 5Fig. 5
Affiliation: School of Optometry, Indiana University, 800 Atwater Avenue, Bloomington, Indiana 47405, USA. email@example.com