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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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The relay scanning pair. (a) Incoming direction, the scanning relay pair DPS 1-2 focus the incoming narrow laser beams to the center of entrance pupil (EP) from the scanning center; (b) In the outgoing direction, the DPS design minimizes and balance the instrumental aberration along different paths.
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g003: The relay scanning pair. (a) Incoming direction, the scanning relay pair DPS 1-2 focus the incoming narrow laser beams to the center of entrance pupil (EP) from the scanning center; (b) In the outgoing direction, the DPS design minimizes and balance the instrumental aberration along different paths.

Mentions: The critical element for achieving the design goals specified above, in both incoming and outgoing paths, is the custom-designed, three-element, double-pass scanning-lens (DPS1-4 in Fig. 1). In the incoming direction, the relay telescope DPS3-4 conjugates the rotation axes of X & Y scanning mirrors and forms a compact scanning center for field angles up to 15° in all meridians. This scanning center is further conjugated to the EP center of the eye over the 15° field via telescope DPS 1-2 as shown in Fig. 3(a)Fig. 3


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)

The relay scanning pair. (a) Incoming direction, the scanning relay pair DPS 1-2 focus the incoming narrow laser beams to the center of entrance pupil (EP) from the scanning center; (b) In the outgoing direction, the DPS design minimizes and balance the instrumental aberration along different paths.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

g003: The relay scanning pair. (a) Incoming direction, the scanning relay pair DPS 1-2 focus the incoming narrow laser beams to the center of entrance pupil (EP) from the scanning center; (b) In the outgoing direction, the DPS design minimizes and balance the instrumental aberration along different paths.
Mentions: The critical element for achieving the design goals specified above, in both incoming and outgoing paths, is the custom-designed, three-element, double-pass scanning-lens (DPS1-4 in Fig. 1). In the incoming direction, the relay telescope DPS3-4 conjugates the rotation axes of X & Y scanning mirrors and forms a compact scanning center for field angles up to 15° in all meridians. This scanning center is further conjugated to the EP center of the eye over the 15° field via telescope DPS 1-2 as shown in Fig. 3(a)Fig. 3

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