Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors

Omer P. Kocaoglu, Ravi Jonnal, Sangyeol Lee, Qiang Wang, Zhuolin Liu, Donald T. Miller

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Optical coherence tomography with adaptive optics (AO-OCT) is a noninvasive method for imaging the living retina at the microscopic level. We used AO-OCT technology to follow changes in cone photoreceptor outer segment (OS) length and reflectance. To substantially increase sensitivity of the length measurements, a novel phase retrieval technique was demonstrated, capable of detecting changes on a nanometer scale. We acquired volume videos of 0.65°x0.65° retinal patches at 1.5° temporal to the fovea over 75 and 105 minutes in two subjects. Volumes were dewarped and registered, after which the cone intensity, OS length, and referenced phase difference were tracked over time. The reflections from inner segment/OS junction (IS/OS) and posterior tips of OS (PT) showed significant intensity variations over time. In contrast, the OS length as measured from the intensity images did not change, indicative of a highly stable OS length at least down to the level of the system's axial resolution (3μm). Smaller axial changes, however, were detected with our phase retrieval technique. Specifically, the PT-IS/OS phase difference for the same cones showed significant variation, suggesting real sub-wavelength changes in OS length of 125±46 nm/hr for the 22 cones followed. We believe these length changes are due to the normal renewal process of the cone OS that elongate the OS at a rate of about 100 nm/hr. The phase difference measurements were strongly correlated among Alines within the same cone (0.65 radians standard deviation) corresponding to a length sensitivity of 31 nm, or ~100 times smaller than the axial resolution of our system.

Original languageEnglish (US)
Title of host publicationOphthalmic Technologies XXII
Volume8209
DOIs
StatePublished - Apr 2 2012
Externally publishedYes
EventOphthalmic Technologies XXII - San Francisco, CA, United States
Duration: Jan 21 2012Jan 22 2012

Other

OtherOphthalmic Technologies XXII
CountryUnited States
CitySan Francisco, CA
Period1/21/121/22/12

Keywords

  • Adaptive Optics
  • Cone Photoreceptors
  • Optical Coherence Tomography
  • Phase Sensitive Imaging

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Radiology Nuclear Medicine and imaging

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  • Cite this

    Kocaoglu, O. P., Jonnal, R., Lee, S., Wang, Q., Liu, Z., & Miller, D. T. (2012). Adaptive optics optical coherence tomography for measuring phase and reflectance dynamics of photoreceptors. In Ophthalmic Technologies XXII (Vol. 8209). [82091I] https://doi.org/10.1117/12.910530