April 2011
Volume 52, Issue 14
Free
ARVO Annual Meeting Abstract  |   April 2011
Wavefront Sensorless Adaptive Optics for the Human Eye
Author Affiliations & Notes
  • Heidi J. Hofer
    College of Optometry, University of Houston, Houston, Texas
  • Nripun Sredar
    College of Optometry, University of Houston, Houston, Texas
  • Hope M. Queener
    College of Optometry, University of Houston, Houston, Texas
  • Lukasz Sterkowicz
    College of Optometry, University of Houston, Houston, Texas
  • Jason Porter
    College of Optometry, University of Houston, Houston, Texas
  • Footnotes
    Commercial Relationships  Heidi J. Hofer, None; Nripun Sredar, None; Hope M. Queener, None; Lukasz Sterkowicz, None; Jason Porter, None
  • Footnotes
    Support  NIH grants EY019069 and EY007551, Texas Advanced Research Program grant G096152
Investigative Ophthalmology & Visual Science April 2011, Vol.52, 4058. doi:
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      Heidi J. Hofer, Nripun Sredar, Hope M. Queener, Lukasz Sterkowicz, Jason Porter; Wavefront Sensorless Adaptive Optics for the Human Eye. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4058.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: : To assess the feasibility of wavefront sensorless adaptive optics (SAO) control as an alternative to wavefront sensor (WFS)-based control for imaging the living human retina.

Methods: : We compared the quality of confocal adaptive optics scanning laser ophthalmoscope (AOSLO) photoreceptor images (840 nm) after WFS-based and SAO control in 5 human subjects with natural (3-6 mm) and dilated (8 mm) pupils. A deformable mirror (Mirao 52-e) first corrected lower order aberrations. A BMC MEMS deformable mirror dynamically corrected higher order aberrations using (1) a Shack-Hartmann WFS-based control method (10 Hz) or (2) an SAO control method (12.5 Hz) in which the 140 MEMS actuator voltages were directly optimized via a stochastic gradient parallel descent (SGPD) algorithm to maximize the mean light intensity of AOSLO images. SGPD gain parameters were selected to yield optimal convergence speed and intensity. A suppression scheme prevented mirror adjustment during blinks.

Results: : Convergence was slower with SAO than with WFS-based control. Mean image intensities after SAO and WFS-based control were similar in 4 of 5 undilated eyes, while mean image intensity was higher after WFS-based control in 4 of 5 dilated eyes. Despite similar or reduced intensities, the relative spectral power densities of AOSLO registered images were preserved or enhanced at higher spatial frequencies following SAO (compared to WFS-based control) in 4 of 5 eyes. SAO also successfully corrected 1 subject whose small natural pupil precluded successful WFS-based control. Assessment of non-common path errors with SAO indicated these were not responsible for its comparative success.

Conclusions: : SAO is feasible in the human eye and produces retinal images that compare favorably with those from WFS-based methods. SAO is particularly advantageous with natural, undilated pupils and may succeed in cases where wavefront sensing is not possible. Preliminary work with modal mirror control and a detection scheme with a flexible integration area indicate the possibility of increasing convergence speed and robustness. SAO could ultimately provide simpler, lower cost systems with improved corrections using less incident light than WFS-based methods. Aberration correction and high-resolution imaging using lower light levels would be especially beneficial for psychophysics and autofluorescence imaging.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: non-clinical • photoreceptors 
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