Impact of retinal vascular tortuosity on retinal circulation

Malek, Jihene; Azar, Ahmad Taher; Tourki, Rached

doi:10.1007/s00521-014-1657-2

Cited by 25 publications

(16 citation statements)

References 51 publications

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“…Venules exhibit different optimal flow characteristics across the vascular network compared with arterioles due to different physiological function [ 46 ]. An increase in venular tortuosity is associated with pressure drop and decrease in blood velocity leading to sluggish blood flow [ 47 ]. Indeed, an increase in venular tortuosity has been associated with systemic (such as hypertension and ischemic heart disease mortality) [ 48 , 49 ] as well as ocular diseases (such as diabetic retinopathy and central retinal vein occlusion) [ 50 , 51 ].…”

Section: Discussionmentioning

confidence: 99%

Association of serum lutein and zeaxanthin with quantitative measures of retinal vascular parameters

et al. 2018

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To evaluate the association between serum carotenoids and quantitative measures of retinal vasculature in elderly Singapore Chinese subjects. The following details were collected in 128 healthy subjects: sociodemographics, lifestyle information, medical and drug history, and anthropometric measurements. Serum concentrations of carotenoids were estimated in fasting venous blood using high performance liquid chromatography. Retinal vascular parameters were quantitatively measured from retinal photographs using a computer-assisted program (Singapore I Vessel Assessment). The mean age of the population was 54.1 years (range 40 to 81 years). In multiple linear regression analysis, per SD decrease in retinal arteriolar caliber [β = 0.045 (0.003 to 0.086), p = 0.036], per SD increase in retinal venular caliber [β = -0.045 (-0.086 to -0.003), p = 0.036] and per SD increase in arteriolar branching angle [β = -0.039 (-0.072 to -0.006), p = 0.021] were associated with decreased serum lutein. Per SD increase in retinal venular tortuosity [β = -0.0075 (-0.0145 to -0.0004), p = 0.039] and per SD increase in arteriolar branching angle (β = -0.0073 [-0.0142 to -0.0059], p = 0.041) were associated with decreased serum zeaxanthin. None of the other carotenoids demonstrated meaningful relationship with quantitative measures of retinal vasculature. Lower levels of lutein and zeaxanthin demonstrated significant relationship with adverse quantitative measures of retinal vasculature in elderly healthy subjects.

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Section: Discussionmentioning

confidence: 99%

Association of serum lutein and zeaxanthin with quantitative measures of retinal vascular parameters

et al. 2018

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“…Blood and tissue oxygenation, however, are not predicted with this model. This model was later used to study the effect of topological changes (such as tortuosity) on hemodynamics in retinal circulation [13]. Ganesan et al [14,15] presented an image-based network model of the murine retinal vasculature using confocal microscopy images.…”

Section: Introductionmentioning

confidence: 99%

Predicting retinal tissue oxygenation using an image-based theoretical model

Fry

Coburn

Whiteman

et al. 2018

Mathematical Biosciences

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Impaired oxygen delivery and tissue perfusion have been identified as significant factors that contribute to the loss of retinal ganglion cells in glaucoma patients. This study predicts retinal blood and tissue oxygenation using a theoretical model of the retinal vasculature based on confocal microscopy images of the mouse retina. These images reveal a complex and heterogeneous geometry of vessels that are distributed non-uniformly into multiple distinct retinal layers at varying depths. Predicting oxygen delivery and distribution in this irregular arrangement of retinal microvessels requires the use of an efficient theoretical model. The model employed in this work utilizes numerical methods based on a Green's function approach to simulate the spatial distribution of oxygen levels in a network of retinal blood vessels and the tissue surrounding them. Model simulations also predict the blood flow rates and pressures in each of the microvessels throughout the entire network. As expected, the model predicts that average vessel PO decreases as oxygen demand is increased. However, the standard deviation of PO in the vessels nearly doubles as oxygen demand is increased from 1 to 8 cm O/100 cm/min, indicating a very wide spread in the predicted PO levels, suggesting that average PO is not a sufficient indicator of oxygenation in a heterogeneous vascular network. Ultimately, the development of this mathematical model will help to elucidate the important factors associated with blood flow and metabolism that contribute to the vision loss characteristic of glaucoma.

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“…For decades, the automatic methods for extracting and measuring the vessels in retinal images have been required to save the workload of ophthalmologists and to assist in characterizing the detected lesions and identifying the false positives [87,[96][97][98][99][100][101]. However, the use of Therefore, an image pre-processing is required before any treatment.…”

Section: Real Image Resultsmentioning

confidence: 99%

Adaptive noise-reducing anisotropic diffusion filter

Abdallah

Malek

Azar

et al. 2015

Neural Comput & Applic

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In image processing and computer vision, the denoising process is an important step before several processing tasks. This paper presents a new adaptive noisereducing anisotropic diffusion (ANRAD) method to improve the image quality, which can be considered as a modified version of a speckle-reducing anisotropic diffusion (SRAD) filter. The SRAD works very well for monochrome images with speckle noise. However, in the case of images corrupted with other types of noise, it cannot provide optimal image quality due to the inaccurate noise model. The ANRAD method introduces an automatic RGB noise model estimator in a partial differential equation system similar to the SRAD diffusion, which estimates at each iteration an upper bound of the real noise level function by fitting a lower envelope to the standard deviations of pre-segment image variances. Compared to the conventional SRAD filter, the proposed filter has the advantage of being adapted to the color noise produced by today's CCD digital camera. The simulation results show that the ANRAD filter can reduce the noise while preserving image edges and fine details very well. Also, it is favorably compared to the fast non-local means filter, showing an improvement in the quality of the restored image. A quantitative comparison measure is given by the parameters like the mean structural similarity index and the peak signal-to-noise ratio.

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Impact of retinal vascular tortuosity on retinal circulation

Cited by 25 publications

References 51 publications

Association of serum lutein and zeaxanthin with quantitative measures of retinal vascular parameters

Association of serum lutein and zeaxanthin with quantitative measures of retinal vascular parameters

Predicting retinal tissue oxygenation using an image-based theoretical model

Adaptive noise-reducing anisotropic diffusion filter

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