Computer-assisted photoreceptor assessment on Heidelberg Engineering Spectralis™ High Magnification Module™ images

Abstract Purpose To evaluate reliability and repeatability of computer-assisted measurements of cone photoreceptor metrics on Heidelberg Engineering Spectralis™ High Magnification Module (HMM™) Automatic Real-time Tracking (ART™) images. Methods We analyzed HMM™ images in three separate study arms. Computer-assisted cone identification software was validated using an open-access adaptive optics (AO) dataset. We compared results of the first arm to data from AO and histology. We evaluated intersession repeatability of our computer-assisted cone analysis in the second arm. We assessed the capability of HMM™ to visualize cones in the presence of pathology in the third arm. Results We included 10 healthy subjects in the first arm of our study, 5 additional healthy participants in the second arm and 5 patients in the third arm. In total, we analyzed 225 regions of interest on HMM™ images. We were able to automatically identify cone photoreceptors and assess corresponding metrics at all eccentricities between 2 and 9° from the fovea. Cone density significantly declined with increasing eccentricity (p = 4.890E-26, Friedman test). With increasing eccentricity, we found a significant increase in intercell distance (p = 2.196E-25, Friedman test) and nearest neighbor distance (p = 1.997E-25, Friedman test). Cone hexagonality ranged between 71 and 85%. We found excellent automated intersession repeatability of cone density counts and spacing measurements. In pathology, we were also able to repeatedly visualize photoreceptors. Conclusion Computer-assisted cone photoreceptor analysis on Spectralis™ HMM™ images is feasible, and most cone metrics show excellent repeatability. HMM™ imaging may be useful for photoreceptor analysis as progression marker in outer retinal disease.

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Human foveal cone photoreceptor topography and its dependence on eye length

eLife ◽

10.7554/elife.47148 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 10

Author(s):

Yiyi Wang ◽

Nicolas Bensaid ◽

Pavan Tiruveedhula ◽

Jianqiang Ma ◽

Sowmya Ravikumar ◽

...

Keyword(s):

Visual Acuity ◽

Adaptive Optics ◽

Axial Length ◽

Visual Angle ◽

Cone Photoreceptor ◽

Foveal Vision ◽

Cone Mosaic ◽

New Generation ◽

Myopic Progression ◽

Cone Density

We provide the first measures of foveal cone density as a function of axial length in living eyes and discuss the physical and visual implications of our findings. We used a new generation Adaptive Optics Scanning Laser Ophthalmoscope to image cones at and near the fovea in 28 eyes of 16 subjects. Cone density and other metrics were computed in units of visual angle and linear retinal units. The foveal cone mosaic in longer eyes is expanded at the fovea, but not in proportion to eye length. Despite retinal stretching (decrease in cones/mm2), myopes generally have a higher angular sampling density (increase in cones/deg2) in and around the fovea compared to emmetropes, offering the potential for better visual acuity. Reports of deficits in best-corrected foveal vision in myopes compared to emmetropes cannot be explained by increased spacing between photoreceptors caused by retinal stretching during myopic progression.

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Reduced foveal cone density in early idiopathic macular telangiectasia

BMJ Open Ophthalmology ◽

10.1136/bmjophth-2020-000603 ◽

2021 ◽

Vol 6 (1) ◽

pp. e000603

Author(s):

Hongxin Song ◽

Ethan A Rossi ◽

David R Williams

Keyword(s):

Adaptive Optics ◽

Cellular Level ◽

Cone Photoreceptor ◽

Cone Photoreceptors ◽

Clinically Normal ◽

Macular Telangiectasia ◽

Idiopathic Macular Telangiectasia ◽

Retinal Capillaries ◽

Manual Correction ◽

Cone Density

ObjectiveIdiopathic macular telangiectasia (MacTel) is considered primarily a vascular disease affecting juxtafoveal retinal capillaries. However, recent evidence suggests that neuronal changes may occur early in disease development. We used high-resolution adaptive optics retinal imaging to elucidate the foveal cone photoreceptor changes at a cellular level in patients with MacTel.Methods and analysisWe used adaptive optics scanning light ophthalmoscopy (AOSLO) to evaluate the foveal cone photoreceptors in the less-affected eye of patients with asymmetric MacTel. AOSLO images of cone photoreceptors were obtained in a 4°×4° area centred on the foveola. Individual cone positions were identified within a 2°×2° area centred on the fovea, using semiautomatic cone marking software with manual correction, permitting calculation of a map of cone density.ResultsIn all participants, one eye was affected with MacTel, the fellow eye was clinically normal or near normal, with visual acuity of 20/25 or better and subtle angiographic leakage. The foveal cone mosaics were continuous with tight packing and cones exhibited normal reflectivity. However, cone density was significantly lower for all participants (mean=80 733 cones/mm2) within 0.5° than the cone density previously reported for normal eyes.ConclusionsFoveal cone density is lower than normal in the clinically less-affected eyes of patients with asymmetric MacTel. This suggests that cone photoreceptor loss may precede classic obvious vascular changes in idiopathic MacTel.

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Methods for investigating the local spatial anisotropy and the preferred orientation of cones in adaptive optics retinal images

Visual Neuroscience ◽

10.1017/s0952523816000018 ◽

2016 ◽

Vol 33 ◽

Cited By ~ 4

Author(s):

ROBERT F. COOPER ◽

MARCO LOMBARDO ◽

JOSEPH CARROLL ◽

KENNETH R. SLOAN ◽

GIUSEPPE LOMBARDO

Keyword(s):

Adaptive Optics ◽

Intensity Variation ◽

Retinal Disease ◽

Retinal Images ◽

Cone Photoreceptor ◽

Good Image Quality ◽

High Agreement ◽

Spatial Anisotropy ◽

Cone Mosaic ◽

The Fourier Transform

AbstractThe ability to noninvasively image the cone photoreceptor mosaic holds significant potential as a diagnostic for retinal disease. Central to the realization of this potential is the development of sensitive metrics for characterizing the organization of the mosaic. Here we evaluated previously-described and newly-developed (Fourier- and Radon-based) methods of measuring cone orientation in simulated and real images of the parafoveal cone mosaic. The proposed algorithms correlated well across both simulated and real mosaics, suggesting that each algorithm provides an accurate description of photoreceptor orientation. Despite high agreement between algorithms, each performed differently in response to image intensity variation and cone coordinate jitter. The integration property of the Fourier transform allowed the Fourier-based method to be resistant to cone coordinate jitter and perform the most robustly of all three algorithms. Conversely, when there is good image quality but unreliable cone identification, the Radon algorithm performed best. Finally, in cases where the cone coordinate reliability was excellent, the method previously described by Pum and colleagues performed best. These descriptors are complementary to conventional descriptive metrics of the cone mosaic, such as cell density and spacing, and have the potential to aid in the detection of photoreceptor pathology.

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Human Foveal Cone Photoreceptor Topography and its Dependence on Eye Length

10.1101/589135 ◽

2019 ◽

Cited By ~ 1

Author(s):

Yiyi Wang ◽

Nicolas Bensaid ◽

Pavan Tiruveedhula ◽

Jianqiang Ma ◽

Sowmya Ravikumar ◽

...

Keyword(s):

Visual Acuity ◽

Adaptive Optics ◽

Axial Length ◽

Visual Angle ◽

Cone Photoreceptor ◽

Foveal Vision ◽

Cone Mosaic ◽

New Generation ◽

Myopic Progression ◽

Cone Density

AbstractWe provide the first measures of foveal cone density as a function of axial length in living eyes and discuss the physical and visual implications of our findings. We used a new generation Adaptive Optics Scanning Laser Ophthalmoscope to image cones at and near the fovea in 28 eyes of 16 subjects. Cone density and other metrics were computed in units of visual angle and linear retinal units. The foveal cone mosaic in longer eyes is expanded at the fovea, but not in proportion to eye length. Despite retinal stretching (decrease in cones/mm2), myopes generally have a higher angular sampling density (increase in cones/deg2) in and around the fovea compared to emmetropes, offering the potential for better visual acuity. Reports of deficits in best-corrected foveal vision in myopes compared to emmetropes cannot be explained by increased spacing between photoreceptors caused by retinal stretching during myopic progression.

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Cone photoreceptor dysfunction in retinitis pigmentosa revealed by optoretinography

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2107444118 ◽

2021 ◽

Vol 118 (47) ◽

pp. e2107444118

Author(s):

Ayoub Lassoued ◽

Furu Zhang ◽

Kazuhiro Kurokawa ◽

Yan Liu ◽

Marcel T. Bernucci ◽

...

Keyword(s):

Retinitis Pigmentosa ◽

Adaptive Optics ◽

Vision Loss ◽

Photoreceptor Cells ◽

Segment Length ◽

Cone Photoreceptor ◽

Cone Cells ◽

Common Group ◽

Cone Density

Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerative diseases, whose most debilitating phase is cone photoreceptor death. Perimetric and electroretinographic methods are the gold standards for diagnosing and monitoring RP and assessing cone function. However, these methods lack the spatial resolution and sensitivity to assess disease progression at the level of individual photoreceptor cells, where the disease originates and whose degradation causes vision loss. High-resolution retinal imaging methods permit visualization of human cone cells in vivo but have only recently achieved sufficient sensitivity to observe their function as manifested in the cone optoretinogram. By imaging with phase-sensitive adaptive optics optical coherence tomography, we identify a biomarker in the cone optoretinogram that characterizes individual cone dysfunction by stimulating cone cells with flashes of light and measuring nanometer-scale changes in their outer segments. We find that cone optoretinographic responses decrease with increasing RP severity and that even in areas where cone density appears normal, cones can respond differently than those in controls. Unexpectedly, in the most severely diseased patches examined, we find isolated cones that respond normally. Short-wavelength–sensitive cones are found to be more vulnerable to RP than medium- and long-wavelength–sensitive cones. We find that decreases in cone response and cone outer-segment length arise earlier in RP than changes in cone density but that decreases in response and length are not necessarily correlated within single cones.

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Oxygen vacancy migration in CSZ using density functional theory

MRS Proceedings ◽

10.1557/proc-1122-o03-08 ◽

2008 ◽

Vol 1122 ◽

Author(s):

Byeong-Eon Lee ◽

Dae-Hee Kim ◽

Yeong-Cheol Kim

Keyword(s):

Density Functional Theory ◽

Oxygen Vacancy ◽

Density Functional ◽

Oxygen Vacancies ◽

Nearest Neighbor ◽

Functional Theory ◽

The Third ◽

Vacancy Migration ◽

Neighbor Site ◽

Formation Energies

AbstractWe studied oxygen migration in calcia-stabilized cubic zirconia (CSZ) using density functional theory. A Ca atom was substituted for a Zr atom in a 2×2×2 ZrO2 cubic supercell, and an oxygen vacancy was produced to satisfy the charge neutrality condition. We found that the formation energies of an oxygen vacancy, as a function of its location with respect to the Ca atom, were varied. The relative formation energies of the oxygen vacancies located at the first-, second-, third-, and fourth-nearest-neighbors were 0.0, −0.07, 0.19, and 0.19 eV, respectively. Therefore, the oxygen vacancy located at the second-nearest-neighbor site of the Ca atom was the most favorable, the oxygen vacancy located at the first-nearest-neighbor site was the second most favorable, and the oxygen vacancies at the third- and fourth-nearest-neighbor sites were the least favorable. We also calculated the energy barriers for the oxygen vacancy migration between oxygen sites. The energy barriers between the first and the second nearest sites, the second and third nearest sites, and the third and fourth nearest sites were 0.11, 0.46, and 0.23 eV, respectively. Therefore, the oxygen vacancies favored the first- and second-nearest-neighbor oxygen sites when they drifted under an electric field.

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Mandibular Advancement Improves the Laryngeal View during Direct Laryngoscopy Performed by Inexperienced Physicians

Anesthesiology ◽

10.1097/00000542-200403000-00020 ◽

2004 ◽

Vol 100 (3) ◽

pp. 598-601 ◽

Cited By ~ 16

Author(s):

Miki Tamura ◽

Teruhiko Ishikawa ◽

Rie Kato ◽

Shiroh Isono ◽

Takashi Nishino

Keyword(s):

Direct Laryngoscopy ◽

Statistical Difference ◽

Elective Surgery ◽

Muscle Relaxation ◽

Mandibular Advancement ◽

Friedman Test ◽

Rating Score ◽

Laryngeal View ◽

Statistical Comparison ◽

The Third

Background When oral or nasal fiberoptic laryngoscopy is attempted, mandibular advancement has been reported to improve the laryngeal view. The authors hypothesized that mandibular advancement may also improve the laryngeal view during direct laryngoscopy. Methods Forty patients undergoing elective surgery under general anesthesia were included in this study. After establishment of an adequate level of anesthesia and muscle relaxation, direct laryngoscopy was performed by inexperienced physicians. Four different maneuvers--simple direct laryngoscopy without any assistance (C), simple direct laryngoscopy with mandibular advancement (M), simple direct laryngoscopy with the BURP maneuver (backward, upward, rightward pressure maneuver of the larynx; B), and simple direct laryngoscopy with both mandibular advancement and the BURP maneuver (BM)--were attempted in each subject, and the laryngeal aperture was videotaped with each procedure. An instructor in anesthesiology who was blinded to the procedure evaluated the visualization by reviewing videotape off-line, using the Cormack-Lehane classification system (grades I-IV) and a rating score within each subject (1 = best view; 4 = poorest view). The Friedman test followed by the Student-Newman-Keuls test was performed for statistical comparison. P < 0.05 was considered significant. Results The laryngeal view was improved with M and B when compared with C (P < 0.05 by both rating and Cormack-Lehane evaluation). BM was the most effective method to visualize the laryngeal aperture (P < 0.05, vs. B and M by rating evaluation), whereas B and M were the second and the third most effective methods, respectively. No statistical difference was observed between B and M with the Cormack-Lehane classification. Conclusion Mandibular advancement improves the laryngeal view during direct laryngoscopy performed by inexperienced physicians.

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Stabilization and modulation of the topological magnetic phase with a Z2 -vortex lattice in the Kitaev-Heisenberg honeycomb model: The key role of the third-nearest-neighbor interaction

Physical Review B ◽

10.1103/physrevb.98.054413 ◽

2018 ◽

Vol 98 (5) ◽

Cited By ~ 1

Author(s):

Xiaoyan Yao ◽

Shuai Dong

Keyword(s):

Vortex Lattice ◽

Nearest Neighbor ◽

Magnetic Phase ◽

Neighbor Interaction ◽

The Third

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Entanglement perturbation theory for infinite quasi-1D quantum systems

International Journal of Modern Physics B ◽

10.1142/s0217979215500423 ◽

2015 ◽

Vol 29 (07) ◽

pp. 1550042 ◽

Cited By ~ 1

Author(s):

Lihua Wang ◽

Sung Gong Chung

Keyword(s):

Phase Diagram ◽

Perturbation Theory ◽

Nearest Neighbor ◽

Quantum Systems ◽

Easy Plane ◽

Heisenberg Chain ◽

The Third ◽

Plane Anisotropy ◽

Improved Accuracy

We develop entanglement perturbation theory (EPT) for infinite Quasi-1D quantum systems. The spin-1/2 Heisenberg chain with ferromagnetic nearest neighbor (NN) and antiferromagnetic next nearest neighbor (NNN) interactions with an easy-plane anisotropy is studied as a prototypical system. The obtained phase diagram is compared with a recent prediction [Phys. Rev. B 81, 094430 (2010)] that dimer and Néel orders appear alternately as the XXZ anisotropy Δ approaches the isotropic limit Δ = 1. The first and second transitions (across dimer, Néel and dimer phases) are detected with improved accuracy at Δ ≈ 0.722 and 0.930. The third transition (from dimer to Néel phases), previously predicted to be at Δ ≈ 0.98, is not detected at this Δ in our method, strongly indicating that the second Néel phase is absent.

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