Spectral analysis of spatial sampling by photoreceptors: Topological disorder prevents aliasing

Yellott, John I.

doi:10.1016/0042-6989(82)90086-4

Cited by 181 publications

(105 citation statements)

References 7 publications

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“…16 , 17 We will refer to the distance between the origin and the peak of this annulus as the modal frequency of the mosaic. We then define the modal cone spacing as the reciprocal of the modal frequency.…”

Section: Resultsmentioning

confidence: 99%

“…Anatomical evidence suggests that the extrafoveal cone array is less regular than that of the fovea.1"' 2 -' 5 Irregular arrays are expected to produce irregular moir6 patterns, whose energy is smeared across a range of spatial frequencies and orientations. 16 "1 7 Williams and Collier1 8 have argued that the irregularity of the blue-sensitive cone mosaic accounts for the noisy appearance of fine violet gratings seen against a yellow background that isolates the blue-sensitive mechanism.…”

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confidence: 99%

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Psychophysical estimate of extrafoveal cone spacing

1987

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In the extrafoveal retina, interference fringes at spatial frequencies higher than the resolution limit look like twodimensional spatial noise, the origin of which has not been firmly established. We show that over a limited range of high spatial frequencies this noise takes on a striated appearance, with the striations running perpendicular to the true fringe orientation.A model of cone aliasing based on anatomical measurements of extrafoveal cone position predicts that this orientation reversal should occur when the period of the interference fringe roughly equals the spacing between cones, i.e., when the fringe spatial frequency is about twice the cone Nyquist frequency. Psychophysical measurements of the orientation reversal at retinal eccentricities from 0.75 to 10 deg are in quantitative agreement with this prediction. This agreement implies that at least part of the spatial noise observed under these conditions results from aliasing by the cone mosaic. The orientation reversal provides a psychophysical method for estimating spacing in less regular mosaics, complementing another psychophysical technique for measuring spacing in the more regular mosaic of foveal cones [D. R. Williams, Vision Res. 25, 195 (1985); Vision Res. (submitted)].

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Psychophysical estimate of extrafoveal cone spacing

1987

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“…Figure 3 shows the result. The regular spacing of the photoreceptors should result in the observation of Yellott's rings [14]. Instead in Figs.…”

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confidence: 99%

Simultaneous imaging of human cone mosaic with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography

et al. 2007

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We describe a novel instrument capable of acquiring, simultaneously, adaptive optics enhanced scanning laser ophthalmoscopy and optical coherence tomography (OCT) images of the human cone mosaic in vivo. The OCT system is based on transversal scanning of the sample with a line scan rate of 14 kHz, ϳ20 times faster than a previously reported instrument. We demonstrate the capability of this instrument with the measurement of the human cone spacing in perifoveal retina.

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“…Fig. 2(e)], which corresponds to the spatial frequency of the cone photoreceptors [19,22,31], indicating that we are resolving the cone photoreceptors in this FFOCT image. The circumferentialaveraged power spectrum gives a maximum at 31.6 cyc∕ deg , corresponding to a cone spacing of about 9.5 μm.…”

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confidence: 99%

“…[19,31] for cone spacing at around 6°-7°eccentricity. Retinal imaging has also been done using a commercial AO retinal camera (RTX1, Imagine Eyes, France) around the same retinal layers of the same eye at the same location for comparison.…”

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confidence: 99%

In vivo high-resolution human retinal imaging with wavefront-correctionless full-field OCT

Xiao¹,

Mazlin²,

Grieve³

et al. 2018

Optica

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As the lateral resolution of full-field optical coherence tomography (FFOCT) with spatially incoherent illumination has been shown to be insensitive to aberrations, we demonstrate high-resolution en face FFOCT retinal imaging without wavefront correction in the human eye in vivo for the first time, to our knowledge. A combination of FFOCT with spectraldomain OCT (SDOCT) is applied for real-time matching of the optical path lengths (OPLs) of FFOCT. Through the realtime cross-sectional SDOCT images, the OPL of the FFOCT reference arm is matched with different retinal layers in the FFOCT sample arm. Thus, diffraction-limited FFOCT images of multiple retinal layers are acquired at both the near periphery and the fovea. The en face FFOCT retinal images reveal information about various structures, such as the nerve fiber orientation, the blood vessel distribution, and the photoreceptor mosaic. During its 25 years of development, optical coherence tomography (OCT) has become a powerful imaging modality in biomedical and clinical studies [1,2]. It has achieved great success in ophthalmology [3], especially in retinal imaging for which it has been entitled the "virtual biopsy" for human retina [4]. Compared with typical retinal imaging modalities like fundus cameras [5] or scanning laser ophthalmoscopy (SLO) [6], in which axial resolution is limited by the finite size of the eye's pupil, OCT offers much higher axial sectioning, as the lateral and axial resolutions are decoupled. The high-resolution cross-sectional depth exploration of the retinal layers offers important information about pathologies for early diagnosis of disease and for tracing disease evolution [7][8][9]. While doctors are capable of interpreting crosssectional OCT slices, there is nevertheless a need for en face views, as shown by the continued use of en face techniques such as fundus cameras or SLO. Thanks to the speed improvement, OCT systems can provide en face retinal images by doing real-time 3Dimaging [10][11][12]. Nevertheless, due to the requirement of large depth of focus, low NA is typically used in traditional OCT, resulting in relatively low spatial resolution compared with high-NA systems. To ensure high transverse resolution, en face flying spot OCT has been applied for human retinal imaging, which achieves retinal en face images with transverse scanning [13,14]. To be able to realize close to diffraction-limited lateral resolution in OCT retinal imaging, complex hardware adaptive optics (AO) [15][16][17][18][19] or computational AO [20][21][22] would also be needed to correct the aberrations induced by the imperfections of the cornea and lens in the anterior chamber.Full-field OCT (FFOCT) is a kind of time-domain en face parallel OCT that takes images perpendicular to the optical axis without scanning. By using high-NA microscope objectives in a Linnik interferometer, FFOCT is able to achieve standard microscope spatial resolution [23]. With spatially incoherent illumination, cross talk is severely inhibited in FFOCT compared with wide-...

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Spectral analysis of spatial sampling by photoreceptors: Topological disorder prevents aliasing

Cited by 181 publications

References 7 publications

Psychophysical estimate of extrafoveal cone spacing

Psychophysical estimate of extrafoveal cone spacing

Simultaneous imaging of human cone mosaic with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography

In vivo high-resolution human retinal imaging with wavefront-correctionless full-field OCT

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