title: Complex conjugate artifact-free adaptive optics optical coherence tomography of in vivo human optic nerve head.
abstract: We acquired in vivo images of the human optic nerve head (ONH) using an adaptive optics-optical coherence tomography (AO-OCT) system. In order to improve imaging of the lamina cribrosa in the ONH with high lateral resolution and sensitivity, we implemented a complex conjugate artifact-free Fourier domain OCT (Fd-OCT) acquisition scheme with a reference arm-based phase shifting method. This allowed positioning of the lamina cribrosa structures near the zero path length difference where AO-OCT imaging achieves highest sensitivity. Implementation of our complex conjugate artifact removal (CCR) method required constant phase shifts between consecutive axial scans (A-scans), generated by continuous beam path-length changes from offsetting the pivot point of the scanning mirror placed in the reference arm. Fourier transform along the transverse axis and a filtering algorithm allowed reconstruction of CCR AO-OCT images. The suppression ratio of the mirror artifact was approximately 22 dB (at 18,000 A-scans per second acquisition speed) with a paperboard test target and an optimum phase-shift value. Finally, we reconstructed the three-dimensional structure of human ONH with enhanced depth range and sensitivity using CCR AO-OCT.
authors.affiliation: University of California Davis Eye Center, Vision Science and Advanced Retinal Imaging Laboratory, 4860 Y Street, Suite 2400, Sacramento, California 95817, USA.
authors.forename: Dae Yu
authors.initials: DY
authors.lastname: Kim
authors.forename: John S
authors.initials: JS
authors.lastname: Werner
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Zawadzki
mesh_terms: D000465:Algorithms; D016477:Artifacts; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D007909:Lenses; D008875:Middle Aged; D009898:Optic Disk / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods*