Retinal Vasculature Fractal Dimension Measures Vessel Density

Hamid, Fadilah Ab; Azemin, Mohd Zulfaezal Che; Salam, Adzura; Aminuddin, Amilia; Daud, Norsyazwani Mohd; Zahari, Ilyanoon

doi:10.3109/02713683.2015.1056375

Cited by 18 publications

(20 citation statements)

References 39 publications

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“…A few studies have been conducted to assess the intragrader and intergrader reliability of semi-automated computer programs in generating self-similar pattern of blood vessels networks for retinal vasculature Df measurements. demonstrated high reliability estimates in evaluating retinal complexity with ICC ranging from 0.93 to 0.95 [10,11]. The findings were supported by Bland-Altman analysis which revealed good intergrader agreement for retinal Df with very minimal average differences between graders.…”

Section: Nur Raihan Esa Siti Noor Hakimah Saidi Mohd Zulfaezal Che Azemin Nor Azwani Mohd Shukri Norsham Ahmad Firdaus Yusof @ Aliassupporting

confidence: 55%

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Reliability of Manual Vascular Segmentation for Retinal Fractal Dimension using Peek Retinatm

2019

IJITEE

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Fractal dimension (Df) has been identified as indirect measure in quantifying the complexity of retinal vessel network which is useful for early detection of vascular changes. Reliability studies of Df measurement on retinal vasculature, has been conducted on retinal images processed by using semi-automated software which only permits image with 45ᵒ field of view (FOV). Smartphone-assisted fundus camera retinal image has a maximum 30ᵒ FOV which warrant manual processing in measuring the Df. Retinal blood vessels need to be manually segmented to produce binary images for retinal vasculatures Df measurement. Therefore, this study was conducted to determine the intragrader and intergrader reliability of manual segmentation of the retinal vasculature Df measurement from retinal images taken using a smartphone-assisted fundus camera Forty-five retinal images were captured using the Portable Eye Examination Kit Retina (Peek Retina™, Peek Vision Ltd, UK). Suitable image for Df analysis were selected based on gradable retinal image criteria which included; i) good image focus, ii) centered position of optic nerve head (ONH) and iii) significant blood vessel visibility. The images were cropped 0.5 disc diameters away from disc margin and resized to 500x500 pixels using GNU Image Manipulation Program Version 2.8.18 (GIMP, The GIMP Team, United States). Retinal vessels were manually traced by using layering capabilities for blood vessel segmentation. Df values of segmented blood vessels were measured by using Image J (National Institutes of Health, USA) and its plugin software, FracLac Version 2.5. Intragrader and intergrader reliability was determined by comparing the Df values between; two readings measured one week apart by a grader and readings from two different graders, respectively, using intraclass correlation coefficient (ICC) and Bland-Altman graphical plots. Intragrader agreement for retinal Df showed good reliability with ICC of 0.899 (95% CI: 0.814–0.945). Bland Altman analysis indicated good agreement between Df values at different grading time (mean difference 0.0050; 95% CI:-0.0001–0.0101). Intergrader reliability for retinal Df was high with ICC of 0.814 (95% CI: 0.459–0.919). Bland Altman plot revealed good intergrader agreement for retinal Df between two graders with a bias value of 0.0158 (95% CI: 0.0092–0.0223). In conclusion, manual segmentation of retinal image captured by smartphone-assisted fundus camera has good reliability (0.75 < ICC < 0.9) for Df analysis to study the morphology of retinal vasculatures.

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Section: Nur Raihan Esa Siti Noor Hakimah Saidi Mohd Zulfaezal Che Azemin Nor Azwani Mohd Shukri Norsham Ahmad Firdaus Yusof @ Aliassupporting

confidence: 55%

“…Clear blood vessels visibility (as illustrated in Figure 2). Gradable retinal image was defined as the retinal image with good visibility of blood vasculature without any existence of significant opacity [11].…”

Section: B Retinal Photography and Image Analysismentioning

confidence: 99%

Reliability of Manual Vascular Segmentation for Retinal Fractal Dimension using Peek Retinatm

2019

IJITEE

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“…In 2019 alone, more than 20 research papers addressing the retinal FD, have been registered in MEDLINE. The FD of the retinal vascular network is a measure of its complexity and vessel density (Mainster, 1990;Misson et al, 1992;Masters, 2004;Kwa and Lopez, 2010;Ab Hamid et al, 2016). The retinal vasculature is a transport network delivering oxygen and nutrients to the retinal tissue and removing waste products.…”

Section: Introduction Rationalementioning

confidence: 99%

Systematic Review on Fractal Dimension of the Retinal Vasculature in Neurodegeneration and Stroke: Assessment of a Potential Biomarker

et al. 2020

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Introduction: Ocular manifestations in several neurological pathologies accentuate the strong relationship between the eye and the brain. Retinal alterations in particular can serve as surrogates for cerebral changes. Offering a "window to the brain," the transparent eye enables non-invasive imaging of these changes in retinal structure and vasculature. Fractal dimension (FD) reflects the overall complexity of the retinal vasculature. Changes in FD could reflect subtle changes in the cerebral vasculature that correspond to preclinical stages of neurodegenerative diseases. In this review, the potential of this retinal vessel metric to serve as a biomarker in neurodegeneration and stroke will be explored.Methods: A literature search was conducted, following the PRISMA Statement 2009 criteria, in four large bibliographic databases (Pubmed, Embase, Web Of Science and Cochrane Library) up to 12 October 2019. Articles have been included based upon their relevance. Wherever possible, level of evidence (LOE) has been assessed by means of the Oxford Centre for Evidence-based Medicine Level of Evidence classification.Results: Twenty-one studies were included for qualitative synthesis. We performed a narrative synthesis and produced summary tables of findings of included papers because methodological heterogeneity precluded a meta-analysis. A significant association was found between decreased FD and neurodegenerative disease, mainly addressing cognitive impairment (CI) and dementia. In acute, subacute as well as chronic settings, decreased FD seems to be associated with stroke. Differences in FD between subtypes of ischemic stroke remain unclear. Conclusions:This review provides a summary of the scientific literature regarding the association between retinal FD and neurodegenerative disease and stroke. Central pathology is associated with a decreased FD, as a measure of microvascular network complexity. As retinal FD reflects the global integrity of the cerebral microvasculature, it is an attractive parameter to explore. Despite obvious concerns, mainly due to a lack of methodological standardization, retinal FD Lemmens et al.Retinal Fractals: Neurodegeneration and Stroke remains a promising non-invasive and low-cost diagnostic biomarker for neurodegenerative and cerebrovascular disease. Before FD can be implemented in clinic as a diagnostic biomarker, the research community should strive for uniformization and standardization.

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“…Forty cropped retinal images (20 from each device; PEEK and 3DPO) with its four choices of options were randomly arranged via Google form for evaluation of RIQA. Samsung Galaxy Tab A 8.0 SM-P355 (Samsung C&T Corp., Seoul, Republic of Korea) was used to display the evaluation form (containing the retinal images) with 21% (60.9 lux) of adjusted brightness [23]. Ten optometrists were selected as graders to subjectively evaluate the quality of the retinal image based on their prior knowledge with confidence [24].…”

Section: Retinal Image Photographmentioning

confidence: 99%

Retinal Image Quality Assessment: Portable Eye Examination Kit Retina (Peek Retina)Tm Versus 3d-Printed Ophthalmoscope (3dpo)

2019

IJITEE

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Portable Eye Examination Kit retina (Peek Retina™, Peek Vision Ltd, UK) and 3D Printed Ophthalmoscope (3DPO) were identified to have acceptable image for retinal evaluation, however the retinal images quality in term of blood vessels visibility between both devices was uncertain. This study was conducted to compare the quality of image based on blood vessels visibility between Peek Retina and 3DPO for fractal dimension (Df) analysis. In this study, a total of 40 retinal images (nPEEK=20, n3DPO=20) of 20 participants were captured on random eyes. The best retinal images with good focus and significant retinal blood vessels visibility of Peek Retina and 3DPO were selected for image quality analysis. The retinal images were cropped approximately following the size of the cornea and resized to 900 by 900 pixels of resolution using GNU Image Manipulation Program Version 2.8.18 (GIMP). The images were randomly sorted as Retinal Image Quality Assessment (RIQA) generated by Google form. Likert scale was implemented to assess the preferences scale of retinal image quality in determining the visibility of retinal vasculature to be traced with four choices of response options (1; very difficult, 2; difficult, 3; easy and 4; very easy). Prior to the retinal image assessment, ten optometrists were asked to experience retinal blood vessels tracing and consequently evaluate the 40 images by choosing the scale options (1 to 4) based on visibility retinal blood vessels. Mann-Whitney test indicated that the blood vessel tracing was easier for Peek Retina (median = 3) than for 3DPO (median = 2), p < 0.0001. Retinal image captured by Peek Retina was rated as very easy (43.5%) for blood vessels tracing as compared to the image from 3DPO (17.0%)Error! Reference source not found.. Only 1.5% of the image captured by PEEK was considered as a very difficult for blood vessel tracing. Difficult and easy preference scales of blood vessel tracing for PEEK were 16.5% and 38.5% respectively. 34% of 3DPO retinal image was graded as difficult for blood vessel tracing followed by 28.5% (easy), 20.5% (very difficult) and 17.0% (very easy). The results indicate that a retinal image photographed by Peek Retina was more preferable in tracing retinal vascular network for Df analysis as compared to 3DPO.

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Retinal Vasculature Fractal Dimension Measures Vessel Density

Abstract: This study demonstrated the ability of vessel density measurement to detect the changes in the morphology of retinal microvascular associated with increasing age. Thus, vessel density can be suggested to be another parameter in the quantification of retinal microvasculature.

Cited by 18 publications

References 39 publications

Reliability of Manual Vascular Segmentation for Retinal Fractal Dimension using Peek Retinatm

Reliability of Manual Vascular Segmentation for Retinal Fractal Dimension using Peek Retinatm

Systematic Review on Fractal Dimension of the Retinal Vasculature in Neurodegeneration and Stroke: Assessment of a Potential Biomarker

Retinal Image Quality Assessment: Portable Eye Examination Kit Retina (Peek Retina)Tm Versus 3d-Printed Ophthalmoscope (3dpo)

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