Research Papers

Characteristics of the human isoplanatic patch and implications for adaptive optics retinal imaging

[+] Author Affiliations
Phillip Bedggood, Mary Daaboul, Ross Ashman, George Smith, Andrew Metha

The University of Melbourne, Department of Optometry and Vision Sciences, Parkville, Vic 3052, Australia

J. Biomed. Opt. 13(2), 024008 (April 21, 2008). doi:10.1117/1.2907211
History: Received September 25, 2007; Revised November 12, 2007; Accepted November 14, 2007; Published April 21, 2008
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Conventional adaptive optics enables correction of high-order aberrations of the eye, but only for a single retinal point. When imaging extended regions of the retina, aberrations increase away from this point and degrade image quality. The zone over which aberrations do not change significantly is called the “isoplanatic patch.” Literature concerning the human isoplanatic patch is incomplete. We determine foveal isoplanatic patch characteristics by performing Hartmann-Shack aberrometry in 1deg increments in 8 directions on 7 human eyes. Using these measurements, we establish the correction quality required to yield at least 80% of the potential patch size for a given eye. Single-point correction systems (conventional adaptive optics) and multiple-point correction systems (multiconjugate adaptive optics) are simulated. Results are compared to a model eye. Using the Maréchal criterion for 555-nm light, average isoplanatic patch diameter for our subjects is 0.80±0.10deg. The required order of aberration correction depends on desired image quality over the patch. For the more realistically achievable criterion of 0.1μm root mean square (rms) wavefront error over a 6.0-mm pupil, correction to at least sixth order is recommended for all adaptive optics systems. The most important aberrations to target for a multiconjugate correction are defocus, astigmatism, and coma.

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© 2008 Society of Photo-Optical Instrumentation Engineers


Phillip Bedggood ; Mary Daaboul ; Ross Ashman ; George Smith and Andrew Metha
"Characteristics of the human isoplanatic patch and implications for adaptive optics retinal imaging", J. Biomed. Opt. 13(2), 024008 (April 21, 2008). ; http://dx.doi.org/10.1117/1.2907211

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