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Design and validation of a scanning Shack Hartmann aberrometer for measurements of the eye over a wide field of view.

Wei X, Thibos L - Opt Express (2010)

Bottom Line: The prototype SSHA successfully measured the off-axis wavefront aberrations over +/- 15 degree visual field within 7 seconds.In two validation experiments with a wide angle model eye, it measured change in defocus aberration accurately (<0.02microm, 4mm pupil) and precisely (<0.03microm, 4mm pupil).A preliminary experiment with a human subject suggests its feasibility in clinical applications.

View Article: PubMed Central - PubMed

Affiliation: School of Optometry, Indiana University, Bloomington, Indiana 47405, USA. weix@indiana.edu

ABSTRACT
Peripheral vision and off-axis aberrations not only play an important role in daily visual tasks but may also influence eye growth and refractive development. Thus it is important to measure off-axis wavefront aberrations of human eyes objectively. To achieve efficient measurement, we incorporated a double-pass scanning system with a Shack Hartmann wavefront sensor (SHWS) to develop a scanning Shack Hartmann aberrometer (SSHA). The prototype SSHA successfully measured the off-axis wavefront aberrations over +/- 15 degree visual field within 7 seconds. In two validation experiments with a wide angle model eye, it measured change in defocus aberration accurately (<0.02microm, 4mm pupil) and precisely (<0.03microm, 4mm pupil). A preliminary experiment with a human subject suggests its feasibility in clinical applications.

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Related in: MedlinePlus

Defocus measurements of SSHA along all LoS at various field angles. Horizontal axis indicates the scanning sequence of LoS; vertical axis indicates the magnitude of defocus terms (Z20) over 4 mm pupil. (a) Comparison of the defocus measurements (black dot) with the defocus introduced by the Badal lens (horizontal dash line) along multiple LoS. The masked LoS are those suffered from backward scattering. (b) Comparison of the defocus measurements (black dot) with the defocus introduced by retinal translation (horizontal dashed line) along multiple LoS. The masked LoS are those suffered from backward scattering.
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g004: Defocus measurements of SSHA along all LoS at various field angles. Horizontal axis indicates the scanning sequence of LoS; vertical axis indicates the magnitude of defocus terms (Z20) over 4 mm pupil. (a) Comparison of the defocus measurements (black dot) with the defocus introduced by the Badal lens (horizontal dash line) along multiple LoS. The masked LoS are those suffered from backward scattering. (b) Comparison of the defocus measurements (black dot) with the defocus introduced by retinal translation (horizontal dashed line) along multiple LoS. The masked LoS are those suffered from backward scattering.

Mentions: For the first experiment, the changes in measured wavefront defocus produced by known amounts of defocus introduced by the Badal system are shown in Fig. 4(a)Fig. 4


Design and validation of a scanning Shack Hartmann aberrometer for measurements of the eye over a wide field of view.

Wei X, Thibos L - Opt Express (2010)

Defocus measurements of SSHA along all LoS at various field angles. Horizontal axis indicates the scanning sequence of LoS; vertical axis indicates the magnitude of defocus terms (Z20) over 4 mm pupil. (a) Comparison of the defocus measurements (black dot) with the defocus introduced by the Badal lens (horizontal dash line) along multiple LoS. The masked LoS are those suffered from backward scattering. (b) Comparison of the defocus measurements (black dot) with the defocus introduced by retinal translation (horizontal dashed line) along multiple LoS. The masked LoS are those suffered from backward scattering.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3369549&req=5

g004: Defocus measurements of SSHA along all LoS at various field angles. Horizontal axis indicates the scanning sequence of LoS; vertical axis indicates the magnitude of defocus terms (Z20) over 4 mm pupil. (a) Comparison of the defocus measurements (black dot) with the defocus introduced by the Badal lens (horizontal dash line) along multiple LoS. The masked LoS are those suffered from backward scattering. (b) Comparison of the defocus measurements (black dot) with the defocus introduced by retinal translation (horizontal dashed line) along multiple LoS. The masked LoS are those suffered from backward scattering.
Mentions: For the first experiment, the changes in measured wavefront defocus produced by known amounts of defocus introduced by the Badal system are shown in Fig. 4(a)Fig. 4

Bottom Line: The prototype SSHA successfully measured the off-axis wavefront aberrations over +/- 15 degree visual field within 7 seconds.In two validation experiments with a wide angle model eye, it measured change in defocus aberration accurately (<0.02microm, 4mm pupil) and precisely (<0.03microm, 4mm pupil).A preliminary experiment with a human subject suggests its feasibility in clinical applications.

View Article: PubMed Central - PubMed

Affiliation: School of Optometry, Indiana University, Bloomington, Indiana 47405, USA. weix@indiana.edu

ABSTRACT
Peripheral vision and off-axis aberrations not only play an important role in daily visual tasks but may also influence eye growth and refractive development. Thus it is important to measure off-axis wavefront aberrations of human eyes objectively. To achieve efficient measurement, we incorporated a double-pass scanning system with a Shack Hartmann wavefront sensor (SHWS) to develop a scanning Shack Hartmann aberrometer (SSHA). The prototype SSHA successfully measured the off-axis wavefront aberrations over +/- 15 degree visual field within 7 seconds. In two validation experiments with a wide angle model eye, it measured change in defocus aberration accurately (<0.02microm, 4mm pupil) and precisely (<0.03microm, 4mm pupil). A preliminary experiment with a human subject suggests its feasibility in clinical applications.

Show MeSH
Related in: MedlinePlus