Phase-sensitive imaging of the outer retina using optical coherence tomography and adaptive optics
| Autor: | Donald T. Miller, Omer P. Kocaoglu, Qiang Wang, Ravi S. Jonnal, Sangyeol Lee |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
genetic structures
Phase (waves) ocis:(170.0180) Microscopy ocis:(100.3175) Interferometric imaging 01 natural sciences ocis:(010.1080) Active or adaptive optics 010309 optics 03 medical and health sciences 0302 clinical medicine Optics Optical coherence tomography 0103 physical sciences medicine ocis:(170.4500) Optical coherence tomography ocis:(330.5310) Vision - photoreceptors Optical tomography Adaptive optics Optical path length Physics Retina medicine.diagnostic_test business.industry ocis:(100.5070) Phase retrieval Atomic and Molecular Physics and Optics eye diseases Scanning laser ophthalmoscopy medicine.anatomical_structure 030221 ophthalmology & optometry sense organs Optical Coherence Tomography business Phase retrieval Biotechnology ocis:(100.5088) Phase unwrapping |
| Zdroj: | Biomedical Optics Express |
| ISSN: | 2156-7085 |
| Popis: | The cone photoreceptor’s outer segment (OS) experiences changes in optical path length, both in response to visible stimuli and as a matter of its daily course of renewal and shedding. These changes are of interest, to quantify function in healthy cells and assess dysfunction in diseased ones. While optical coherence tomography (OCT), combined with adaptive optics (AO), has permitted unprecedented three-dimensional resolution in the living retina, it has not generally been able to measure these OS dynamics, whose scale is smaller than OCT’s axial resolution of a few microns. A possible solution is to take advantage of the phase information encoded in the OCT signal. Phase-sensitive implementations of spectral-domain optical coherence tomography (SD-OCT) have been demonstrated, capable of resolving sample axial displacements much smaller than the imaging wavelength, but these have been limited to ex vivo samples. In this paper we present a novel technique for retrieving phase information from OCT volumes of the outer retina. The key component of our technique is quantification of phase differences within the retina. We provide a quantitative analysis of such phase information and show that–when combined with appropriate methods for filtering and unwrapping–it can improve the sensitivity to OS length change by more than an order of magnitude, down to 45 nm, slightly thicker than a single OS disc. We further show that phase sensitivity drops off with retinal eccentricity, and that the best location for phase imaging is close to the fovea. We apply the technique to the measurement of sub-resolution changes in the OS over matters of hours. Using custom software for registration and tracking, these microscopic changes are monitored in hundreds of cones over time. In two subjects, the OS was found to have average elongation rates of 150 nm/hr, values which agree with our previous findings. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|