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Retinal findings in adult leukaemia: correlation with leukocytosis

Jackson N, Reddy SC, Hishamuddin M, Low HC

Clin Lab Haematol, 1996 Jun;18(2):105-9.
PMID: 8866143

The associations between retinal findings and haematological parameters in acute leukaemia are controversial. Sixty-three newly-diagnosed acute leukaemia patients, aged 12-77 years, were studied prospectively for the presence of intra-retinal haemorrhages (IRH), white-centred haemorrhages (WCH), cotton wool spots (CWS) and macular haemorrhages (MH), Thirty-three patients (52.4%) showed at least one retinal abnormality. The prevalence of individual findings was: IRH (30 cases), WCH (20 cases), CWS (5 cases), MH (11 cases). In contrast to previous studies, there was no association between any of these retinal findings and the haemoglobin level or the platelet count. There was a higher median WBC in patients with IRH (68 x 10(9)/l) than in those without IRH (15.4 x 10(9)/l), P = 0.037. When the acute myeloblastic leukaemia cases were considered separately, an association was also found between higher WBC and the presence of WCH and CWS. There was no association between retinal findings and FAB type in the AML cases. We conclude that a high WBC may be at least as important as anaemia and thrombocytopenia in the pathogenesis of the retinopathy of acute leukaemia.

Matched MeSH terms: Retinal Vessels/pathology*
Extraction and reconstruction of retinal vasculature

Ahmad Fadzil MH, Izhar LI, Venkatachalam PA, Karunakar TV

J Med Eng Technol, 2007 Nov-Dec;31(6):435-42.
PMID: 17994417 DOI: 10.1080/03091900601111201

Information about retinal vasculature morphology is used in grading the severity and progression of diabetic retinopathy. An image analysis system can help ophthalmologists make accurate and efficient diagnoses. This paper presents the development of an image processing algorithm for detecting and reconstructing retinal vasculature. The detection of the vascular structure is achieved by image enhancement using contrast limited adaptive histogram equalization followed by the extraction of the vessels using bottom-hat morphological transformation. For reconstruction of the complete retinal vasculature, a region growing technique based on first-order Gaussian derivative is developed. The technique incorporates both gradient magnitude change and average intensity as the homogeneity criteria that enable the process to adapt to intensity changes and intensity spread over the vasculature region. The reconstruction technique reduces the required number of seeds to near optimal for the region growing process. It also overcomes poor performance of current seed-based methods, especially with low and inconsistent contrast images as normally seen in vasculature regions of fundus images. Simulations of the algorithm on 20 test images from the DRIVE database show that it outperforms many other published methods and achieved an accuracy range (ability to detect both vessel and non-vessel pixels) of 0.91 - 0.95, a sensitivity range (ability to detect vessel pixels) of 0.91 - 0.95 and a specificity range (ability to detect non-vessel pixels) of 0.88 - 0.94.

Matched MeSH terms: Retinal Vessels/anatomy & histology*
Diabetic retinopathy: a quadtree based blood vessel detection algorithm using RGB components in fundus images

Reza AW, Eswaran C, Hati S

J Med Syst, 2008 Apr;32(2):147-55.
PMID: 18461818

Blood vessel detection in retinal images is a fundamental step for feature extraction and interpretation of image content. This paper proposes a novel computational paradigm for detection of blood vessels in fundus images based on RGB components and quadtree decomposition. The proposed algorithm employs median filtering, quadtree decomposition, post filtration of detected edges, and morphological reconstruction on retinal images. The application of preprocessing algorithm helps in enhancing the image to make it better fit for the subsequent analysis and it is a vital phase before decomposing the image. Quadtree decomposition provides information on the different types of blocks and intensities of the pixels within the blocks. The post filtration and morphological reconstruction assist in filling the edges of the blood vessels and removing the false alarms and unwanted objects from the background, while restoring the original shape of the connected vessels. The proposed method which makes use of the three color components (RGB) is tested on various images of publicly available database. The results are compared with those obtained by other known methods as well as with the results obtained by using the proposed method with the green color component only. It is shown that the proposed method can yield true positive fraction values as high as 0.77, which are comparable to or somewhat higher than the results obtained by other known methods. It is also shown that the effect of noise can be reduced if the proposed method is implemented using only the green color component.

Matched MeSH terms: Retinal Vessels/physiopathology*
Effect of blood pressure on the retinal vasculature in a multi-ethnic Asian population

Jeganathan VS, Sabanayagam C, Tai ES, Lee J, Sun C, Kawasaki R, et al.

Hypertens Res, 2009 Nov;32(11):975-82.
PMID: 19713968 DOI: 10.1038/hr.2009.130

Blood pressure has a significant effect on retinal arterioles. There are few data on whether this effect varies by race/ethnicity. We examined the relationship of blood pressure and retinal vascular caliber in a multi-ethnic Asian population. The study is population-based and cross sectional in design. A total of 3749 Chinese, Malay and Indian participants aged > or =24 years residing in Singapore were included in the study. Retinal vascular caliber was measured using a computer program from digital retinal photographs. The associations of retinal vascular caliber with blood pressure and hypertension in each racial/ethnic group were analyzed. The main outcome measures are retinal arteriolar caliber and venular caliber. The results show that retinal arterioles were narrower in persons with uncontrolled/untreated hypertension (140.0 microm) as compared with persons with controlled hypertension (142.1 microm, P=0.0001) and those with no hypertension (146.0 microm, P<0.0001). On controlling for age, gender, body mass index, lipids and smoking, each 10 mm Hg increase in mean arterial blood pressure was associated with a 3.1 microm decrease in arteriolar caliber (P<0.0001), with a similar magnitude seen in all three racial/ethnic groups: 3.1 microm in Chinese, 2.8 microm in Malays and 3.2 microm in Indians (P<0.0001 for all). Each 10 mm Hg increase in mean arterial blood pressure was associated with a 1.8 microm increase in venular caliber (P<0.0001); furthermore, the magnitude of this effect was similar across the three racial/ethnic groups. The effect of blood pressure on the retinal vasculature was similar across three major racial/ethnic groups in Asia.

Matched MeSH terms: Retinal Vessels/anatomy & histology; Retinal Vessels/physiology*
A decision support system for automatic screening of non-proliferative diabetic retinopathy

Reza AW, Eswaran C

J Med Syst, 2011 Feb;35(1):17-24.
PMID: 20703589 DOI: 10.1007/s10916-009-9337-y

The increasing number of diabetic retinopathy (DR) cases world wide demands the development of an automated decision support system for quick and cost-effective screening of DR. We present an automatic screening system for detecting the early stage of DR, which is known as non-proliferative diabetic retinopathy (NPDR). The proposed system involves processing of fundus images for extraction of abnormal signs, such as hard exudates, cotton wool spots, and large plaque of hard exudates. A rule based classifier is used for classifying the DR into two classes, namely, normal and abnormal. The abnormal NPDR is further classified into three levels, namely, mild, moderate, and severe. To evaluate the performance of the proposed decision support framework, the algorithms have been tested on the images of STARE database. The results obtained from this study show that the proposed system can detect the bright lesions with an average accuracy of about 97%. The study further shows promising results in classifying the bright lesions correctly according to NPDR severity levels.

Matched MeSH terms: Retinal Vessels/pathology*
Quantitative and qualitative retinal microvascular characteristics and blood pressure

Cheung CY, Tay WT, Mitchell P, Wang JJ, Hsu W, Lee ML, et al.

J Hypertens, 2011 Jul;29(7):1380-91.
PMID: 21558958 DOI: 10.1097/HJH.0b013e328347266c

The present study examined the effects of blood pressure on a spectrum of quantitative and qualitative retinal microvascular signs.

Matched MeSH terms: Retinal Vessels/physiology*
Fulltext An automated blood vessel segmentation algorithm using histogram equalization and automatic threshold selection

Saleh MD, Eswaran C, Mueen A

J Digit Imaging, 2011 Aug;24(4):564-72.
PMID: 20524139 DOI: 10.1007/s10278-010-9302-9

This paper focuses on the detection of retinal blood vessels which play a vital role in reducing the proliferative diabetic retinopathy and for preventing the loss of visual capability. The proposed algorithm which takes advantage of the powerful preprocessing techniques such as the contrast enhancement and thresholding offers an automated segmentation procedure for retinal blood vessels. To evaluate the performance of the new algorithm, experiments are conducted on 40 images collected from DRIVE database. The results show that the proposed algorithm performs better than the other known algorithms in terms of accuracy. Furthermore, the proposed algorithm being simple and easy to implement, is best suited for fast processing applications.

Matched MeSH terms: Retinal Vessels/anatomy & histology*
Fulltext Dramatic response of iris and retinal neovascularisation following usage of intravitreal ranibizumab as pre-operative adjunct in vitrectomy for advanced proliferative diabetic retinopathy

Malisa, A., Mae-Lynn, C.B.

Journal of Surgical Academia, 2011;1(1):61-64.
MyJurnal

A 37-year-old Malay woman presented with progressive deterioration in vision and was diagnosed with advanced proliferative diabetic retinopathy with neovascular glaucoma. Intravitreal ranibizumab injection (an anti-vascular endothelial growth factor) was administered prior to vitrectomy. Slit lamp assessment 2 days post-injection revealed significant regression of both iris and retinal neovascularisation. This resulted in adequate reduction of intra-ocular pressure prior to surgery. In addition, the regression of retinal vessels reduced the risk of intra-operative haemorrhage, thus aiding the surgical excision of the fibrovascular membranes. Periodic post-operative assessment in the first 3 weeks showed minimal inflammation and no recurrence of vitreous haemorrhage. This case illustrates that intravitreal ranibizumab has a role as an adjunct therapy prior to diabetic vitrectomy to significantly reduce the risk of intra-ocular haemorrhage.

Matched MeSH terms: Retinal Vessels
Fulltext Retinal vascular geometry in Asian persons with diabetes and retinopathy

Cheung CY, Lamoureux E, Ikram MK, Sasongko MB, Ding J, Zheng Y, et al.

J Diabetes Sci Technol, 2012 May 01;6(3):595-605.
PMID: 22768891 DOI: 10.1177/193229681200600315

Purpose: Our purpose was to examine the relationship of retinal vascular parameters with diabetes and retinopathy in an older Asian population.

Methods: Retinal photographs from participants of a population-based survey of Asian Malay persons aged 40-80 years were analyzed. Specific retinal vascular parameters (tortuosity, branching angle, fractal dimension, and caliber) were measured using a semiautomated computer-based program. Diabetes was defined as random plasma glucose ≥ 11.1 mmol/liter, the use of diabetes medication, or physician-diagnosed diabetes. Retinopathy signs were graded from photographs using the modified Airlie House classification system.

Results: A total of 2735 persons were included in the study. Persons with diabetes (n = 594) were more likely to have straighter (less tortuous) arterioles and wider arteriolar and venular caliber than those without diabetes (n = 2141). Among subjects with diabetes, those with retinopathy had wider venular caliber than those without retinopathy (211.3 versus 204.9 mm, p = .001). Among nondiabetic subjects, however, those with retinopathy had more tortuous venules than those without retinopathy [5.19(×10(4)) versus 4.27(×10(4)), p < .001].

Conclusions: Retinal vascular parameters varied by diabetes and retinopathy status in this older Asian cohort. Our findings suggest that subtle alterations in retinal vascular architecture are influenced by diabetes.

Matched MeSH terms: Retinal Vessels/pathology*
An efficient algorithm for retinal blood vessel segmentation using h-maxima transform and multilevel thresholding

Saleh MD, Eswaran C

Comput Methods Biomech Biomed Engin, 2012;15(5):517-25.
PMID: 21331960 DOI: 10.1080/10255842.2010.545949

Retinal blood vessel detection and analysis play vital roles in early diagnosis and prevention of several diseases, such as hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. This paper presents an automated algorithm for retinal blood vessel segmentation. The proposed algorithm takes advantage of powerful image processing techniques such as contrast enhancement, filtration and thresholding for more efficient segmentation. To evaluate the performance of the proposed algorithm, experiments were conducted on 40 images collected from DRIVE database. The results show that the proposed algorithm yields an accuracy rate of 96.5%, which is higher than the results achieved by other known algorithms.

Matched MeSH terms: Retinal Vessels/pathology*
Retinal vascular fractal and blood pressure in a multiethnic population

Sng CC, Wong WL, Cheung CY, Lee J, Tai ES, Wong TY

J Hypertens, 2013 Oct;31(10):2036-42.
PMID: 23787404 DOI: 10.1097/HJH.0b013e328362c201

OBJECTIVE(S): To examine the effect of blood pressure (BP) on retinal vascular fractal dimension (Df), a measure of microvascular network complexity and density in a multiethnic cohort.
METHODS: A population-based study of 3876 Chinese, Malay and Indian participants in Singapore. Retinal Df was measured using a computer-based program from digital retinal photographs. Associations between retinal Df and mean arterial BP (MABP) in the whole cohort and in each racial group were analysed using linear regression analysis. Logistic regression was used to examine the association between retinal Df and hypertension status.
RESULTS: The mean retinal Df of the study population was 1.45 (standard deviation 0.03). After adjustment for age, sex, race, diabetes, BMI, cholesterol and creatinine levels, persons with smaller Df had higher MABP (mean difference MABP was 6.18 mmHg comparing lowest to highest Df quartiles, P<0.001). This was similar in Chinese, Malay and Indian persons [mean difference 6.40 (P<0.001), 4.72 (P=0.011) and 6.62 (P<0.001)mmHg, respectively]. Persons with smaller retinal Df were more likely to have uncontrolled treated or untreated hypertension [odds ratio 1.79 (P=0.003) and 2.60 (P=0.003), respectively, comparing lowest to highest Df quartiles] than those with no hypertension; this relationship was not seen comparing persons with controlled treated hypertension with no hypertension (odds ratio 1.01, P=0.972).
CONCLUSION: Hypertension was associated with a sparser retinal vascular network, which was similar across different racial/ethnic groups and most apparent in those with uncontrolled or untreated hypertension. These data suggest that microvascular remodelling can be quantified by measuring retinal vasculature.

Matched MeSH terms: Retinal Vessels/pathology*
Age-related rarefaction in retinal vasculature is not linear

Che Azemin MZ, Ab Hamid F, Aminuddin A, Wang JJ, Kawasaki R, Kumar DK

Exp Eye Res, 2013 Nov;116:355-358.
PMID: 24512773 DOI: 10.1016/j.exer.2013.10.010

The fractal dimension is a global measure of complexity and is useful for quantifying anatomical structures, including the retinal vascular network. A previous study found a linear declining trend with aging on the retinal vascular fractal dimension (DF); however, it was limited to the older population (49 years and older). This study aimed to investigate the possible models of the fractal dimension changes from young to old subjects (10-73 years). A total of 215 right-eye retinal samples, including those of 119 (55%) women and 96 (45%) men, were selected. The retinal vessels were segmented using computer-assisted software, and non-vessel fragments were deleted. The fractal dimension was measured based on the log-log plot of the number of grids versus the size. The retinal vascular DF was analyzed to determine changes with increasing age. Finally, the data were fitted to three polynomial models. All three models are statistically significant (Linear: R2 = 0.1270, 213 d.f., p

Matched MeSH terms: Retinal Vessels
Fulltext A new blood vessel extraction technique using edge enhancement and object classification

Badsha S, Reza AW, Tan KG, Dimyati K

J Digit Imaging, 2013 Dec;26(6):1107-15.
PMID: 23515843 DOI: 10.1007/s10278-013-9585-8

Diabetic retinopathy (DR) is increasing progressively pushing the demand of automatic extraction and classification of severity of diseases. Blood vessel extraction from the fundus image is a vital and challenging task. Therefore, this paper presents a new, computationally simple, and automatic method to extract the retinal blood vessel. The proposed method comprises several basic image processing techniques, namely edge enhancement by standard template, noise removal, thresholding, morphological operation, and object classification. The proposed method has been tested on a set of retinal images. The retinal images were collected from the DRIVE database and we have employed robust performance analysis to evaluate the accuracy. The results obtained from this study reveal that the proposed method offers an average accuracy of about 97 %, sensitivity of 99 %, specificity of 86 %, and predictive value of 98 %, which is superior to various well-known techniques.

Matched MeSH terms: Retinal Vessels/pathology*
Fulltext Resolution of exudative retinal detachment and regression of retinal macrocyst post-laser in Coats disease

Munira Y, Zunaina E, Azhany Y

Int Med Case Rep J, 2013;6:37-9.
PMID: 23966803 DOI: 10.2147/IMCRJ.S47769

A 15-year-old boy presented with painless progressive blurring of vision in the right eye for 1 year in duration. His visual acuity in the right eye was hand movement. The right fundus showed presence of extensive subretinal exudates at the posterior pole and a retinal macrocyst at the temporal periphery. It was associated with exudative retinal detachment at the inferior periphery of the retina. Fundus angiography revealed telangiectatic retinal vessels at the superotemporal retina. Based on clinical and angiographic findings, a diagnosis of Coats disease was made. He was treated with retinal laser photocoagulation. There was resolution of the exudative retinal detachment, reduction of subretinal exudates, and regression of the retinal macrocyst with improvement of visual acuity to 1/60 post-laser therapy.

Matched MeSH terms: Retinal Vessels
Variability and repeatability of quantitative, Fourier-domain optical coherence tomography Doppler blood flow in young and elderly healthy subjects

Tayyari F, Yusof F, Vymyslicky M, Tan O, Huang D, Flanagan JG, et al.

Invest Ophthalmol Vis Sci, 2014 Dec;55(12):7716-25.
PMID: 25335983 DOI: 10.1167/iovs.14-14430

The purpose of this study was to determine the within-session variability and between-session repeatability of spectral Fourier-domain optical coherence tomography (Doppler FD-OCT) Doppler retinal blood flow measurements in young and elderly subjects.

Matched MeSH terms: Retinal Vessels/physiology*
Fulltext Influence of refractive condition on retinal vasculature complexity in younger subjects

Azemin MZ, Daud NM, Ab Hamid F, Zahari I, Sapuan AH

ScientificWorldJournal, 2014;2014:783525.
PMID: 25371914 DOI: 10.1155/2014/783525

The aim of this study was to compare the retinal vasculature complexity between emmetropia, and myopia in younger subjects.

Matched MeSH terms: Retinal Vessels/physiopathology*
Fulltext Zone specific fractal dimension of retinal images as predictor of stroke incidence

Aliahmad B, Kumar DK, Hao H, Unnikrishnan P, Che Azemin MZ, Kawasaki R, et al.

ScientificWorldJournal, 2014;2014:467462.
PMID: 25485298 DOI: 10.1155/2014/467462

Fractal dimensions (FDs) are frequently used for summarizing the complexity of retinal vascular. However, previous techniques on this topic were not zone specific. A new methodology to measure FD of a specific zone in retinal images has been developed and tested as a marker for stroke prediction. Higuchi's fractal dimension was measured in circumferential direction (FDC) with respect to optic disk (OD), in three concentric regions between OD boundary and 1.5 OD diameter from its margin. The significance of its association with future episode of stroke event was tested using the Blue Mountain Eye Study (BMES) database and compared against spectrum fractal dimension (SFD) and box-counting (BC) dimension. Kruskal-Wallis analysis revealed FDC as a better predictor of stroke (H = 5.80, P = 0.016, α = 0.05) compared with SFD (H = 0.51, P = 0.475, α = 0.05) and BC (H = 0.41, P = 0.520, α = 0.05) with overall lower median value for the cases compared to the control group. This work has shown that there is a significant association between zone specific FDC of eye fundus images with future episode of stroke while this difference is not significant when other FD methods are employed.

Matched MeSH terms: Retinal Vessels/pathology
Fulltext Long term outcome in unilaterally treated retinopathy of prematurity: a case report

Mushawiahti, M., Rokiah, O., Umi, K.M.N., Leow, S.N.

Medicine & Health, 2014;9(2):134-138.
MyJurnal

Retinopathy of prematurity (ROP) is a disorder describing an immature vascularisation
of a developing retina in low birth weight preterm infants. This condition potentially
leads to blindness. ROP developed as a response of hypoxia of the eye due to
incomplete development of the retinal vessels. ROP is commonly reported as
bilateral disease,a small percentage of infants have asymmetrical changes. We
report a case of long-term outcome of a asymmetry ROP changes with peripheral
retinal ablation in a single eye. This particular case demonstrates the possible longterm
outcome of unilaterally treated ROP which could either be due to the severity
of the disease itself or the treatment she received. It is important to highlight the
possibility of unequal development of the eye in asymmetrical presentation of ROP.

Matched MeSH terms: Retinal Vessels
Fulltext Relationship between retinal blood flow and arterial oxygen

Cheng RW, Yusof F, Tsui E, Jong M, Duffin J, Flanagan JG, et al.

J Physiol, 2016 Feb 01;594(3):625-40.
PMID: 26607393 DOI: 10.1113/JP271182

KEY POINTS: Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content for all stages of hypoxia used in the present study but can no longer compensate below a PETCO2 of 32-37 mmHg. These vessels have a great vascular range of adjustment, increasing diameter (8.5% arteriolar and 21% total venous area) with hypoxia (40 mmHg P ETC O2; P < 0.001) and decreasing diameter (6.9% arteriolar and 23% total venous area) with hyperoxia (500 mmHg PETCO2; P < 0.001) to the same extent. This indicates that the resting tonus is near the mid-point of the adjustment ranges at resting PaO2 where sensitivity is maximum.

Matched MeSH terms: Retinal Vessels/physiology*
Retinal Vasculature Fractal Dimension Measures Vessel Density

Ab Hamid F, Che Azemin MZ, Salam A, Aminuddin A, Mohd Daud N, Zahari I

Curr Eye Res, 2016 Jun;41(6):823-31.
PMID: 26268475 DOI: 10.3109/02713683.2015.1056375

PURPOSE: The goal of this study was to provide the empirical evidence of fractal dimension as an indirect measure of retinal vasculature density.
MATERIALS AND METHODS: Two hundred retinal samples of right eye [57.0% females (n = 114) and 43.0% males (n = 86)] were selected from baseline visit. A custom-written software was used for vessel segmentation. Vessel segmentation is the process of transforming two-dimensional color images into binary images (i.e. black and white pixels). The circular area of approximately 2.6 optic disc radii surrounding the center of optic disc was cropped. The non-vessels fragments were removed. FracLac was used to measure the fractal dimension and vessel density of retinal vessels.
RESULTS: This study suggested that 14.1% of the region of interest (i.e. approximately 2.6 optic disk radii) comprised retinal vessel structure. Using correlation analysis, vessel density measurement and fractal dimension estimation are linearly and strongly correlated (R = 0.942, R(2) = 0.89, p

Matched MeSH terms: Retinal Vessels/anatomy & histology*

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