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Transformation of Zernike coefficients: scaled, translated, and rotated wavefronts with circular and elliptical pupils
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0002-4894-7944
KTH, School of Engineering Sciences (SCI), Applied Physics, Biomedical and X-ray Physics.ORCID iD: 0000-0001-9172-858X
2007 (English)In: Journal of the Optical Society of America A, ISSN 0740-3232, Vol. 24, no 3, 569-577 p.Article in journal (Refereed) Published
Abstract [en]

Zernike polynomials and their associated coefficients are commonly used to quantify the wavefront aberrations of the eye. When the aberrations of different eyes, pupil sizes, or corrections are compared or averaged, it is important that the Zernike coefficients have been calculated for the correct size, position, orientation, and shape of the pupil. We present the first complete theory to transform Zernike coefficients analytically with regard to concentric scaling, translation of pupil center, and rotation. The transformations are described both for circular and elliptical pupils. The algorithm has been implemented in MATLAB, for which the code is given in an appendix.

Place, publisher, year, edition, pages
2007. Vol. 24, no 3, 569-577 p.
Keyword [en]
Algorithms; Eye movements; MATLAB; Polynomials; Pupils; Zernike coefficients; Vision; algorithm; article; biological model; computer assisted diagnosis; computer simulation; human; image enhancement; iris; keratometry; methodology; physiology; reproducibility; rotation; sensitivity and specificity; vision; Algorithms; Computer Simulation; Corneal Topography; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Iris; Models, Biological; Reproducibility of Results; Rotation; Sensitivity and Specificity; Visual Perception
National Category
Atom and Molecular Physics and Optics
Identifiers
URN: urn:nbn:se:kth:diva-7153DOI: 10.1364/JOSAA.24.000569ISI: 000244407300001PubMedID: 17301846Scopus ID: 2-s2.0-34047118110OAI: oai:DiVA.org:kth-7153DiVA: diva2:12075
Note
QC 20100809Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2010-08-09Bibliographically approved
In thesis
1. Wavefront Aberrations and Peripheral Vision
Open this publication in new window or tab >>Wavefront Aberrations and Peripheral Vision
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Failing eyesight causes a dramatic change in life. The aim of this project is to help people with large central visual field loss to better utilize their remaining vision. Central visual field loss means that the person has to rely on peripheral vision since the direct vision is lost, often due to a dysfunctional macula. In these cases, a full restoration of vision would require replacement or repair of the damaged retinal tissue, which is not yet possible. Instead, the present study seeks to improve peripheral vision by enhancing the image quality on the remaining functional part of the retina by optical corrections. The off-axis optics of the human eye often suffers from large optical errors, which together with the lower sampling density of the retina explain the limited visual function in the periphery. The dominating aberrations are field curvature and oblique astigmatism, which induce an effective eccentric refractive error. However, the irregular character of the aberrations and the limited neural function in the periphery will make it difficult to find the optimal refractive correction; the conventional subjective refraction, for example, is not suitable for subjects with large central visual field loss. Within the work of this thesis a Hartmann-Shack wavefront sensor has been constructed for oblique aberration measurements. Wavefront sensing is an objective method to assess detailed information about the optical errors in the human eye. Theory and methods have been developed to allow accurate off-axis measurements of the large aberrations, enable eccentric fixation, and handle the elliptical pupil. The study has mainly concentrated on sphero-cylindrical correction of peripheral vision. Peripheral resolution and detection acuity thresholds have been evaluated for seven subjects with central visual field loss and ten control subjects with normal vision. Five of the subjects with field loss showed improved resolution acuity with eccentric refractive correction compared to their habitual central correction, whereas little change was found for the control subjects. These results demonstrate that correction of peripheral optical errors can be beneficial to people with large central visual field loss in situations where a normal healthy eye does not experience any improvements. In conclusion, it is worthwhile to investigate the peripheral refractive errors in low-vision rehabilitation of central visual field loss and prescribe spectacle correction when those errors are large.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. ix, 52 p.
Series
Trita-FYS, ISSN 0280-316X ; 2007:34
Keyword
Optics, Human eye, Aberrations, Peripheral vision, Central visual field loss
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-4385 (URN)978-91-7178-665-4 (ISBN)
Public defence
2007-06-01, FD5, KTH, AlbaNova, Roslagstullsbacken 21, Stockholm, 13:00
Opponent
Supervisors
Note
QC 20100809Available from: 2007-05-20 Created: 2007-05-20 Last updated: 2010-08-09Bibliographically approved

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Lundström, LindaUnsbo, Peter

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