• Journal of Veterinary Clinics
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• v.20 no.2
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• pp.145-149
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• 2003

Color Doppler imaging(CDI) was carried out to determine CDI-derived resistive index(RI) values of normal canine ophthalmic vasculature and its reproducibility. CDI was performed on 58 dogs. and normal ranges of RI value were calculated for the medial long posterior ciliary artery(mLPCA), ciliary artery(CA), and ophthalmic artery(OA). Ophthalmic vascular RI values of normal dogs were 0.67$\pm$0.07, 0.70$\pm$0.06, and 0.80$\pm$0.04 in mLPCA, CA, and OA, respectively. Means of RT value of all vessel had no statistically significant difference by sex, fellow orbits, and skull type. The results suggest that color Doppler imaging is a noninvasive test which has the advantage of providing objective measurements of blood flow velocity parameter in the canine eye and orbit.

• Korean Journal of Veterinary Research
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• v.45 no.3
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• pp.423-427
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• 2005

Color Doppler imaging (CDI) was carried out to evaluate the anesthetics effect on ophthalmic circulation using CDI-derived resistive index (RI) values. CDI was preformed on 24 dogs, and RI values were calculated for the medial long posterior ciliary artery (mLPCA) and ophthalmic artery (OA) before and after administration of anesthetics. After administration of benoxinate or acepromazine, a significant change of the mLPCA RI was not found. But, a significant decrease of the RI following ketamine (p < 0.001) or xylazine (p < 0.01) administration could be observed as compared with the self-control. Mean RI value of OA also showed this same trend. Intraocular pressure was significantly decrease following benoxinate (p < 0.01), acepromazine (p < 0.01), and xylazine (p < 0.001) administration within normal range. The results suggest that some anesthetics influence on ophthalmic vascular resistance. Therefore, chemical restraint was carefully used in clinical application of CDI-derived RI measurement. Particularly, benoxinate and acepromazine is useful chemical restraint without a change of the ophthalmic vascular resistance.

• International Journal of Contents
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• v.2 no.3
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• pp.27-32
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• 2006

We present an effective algorithm for automatic tracing of retinal vessel structure and vascular landmark extraction of bifurcations and ending points. In this paper we deal with vascular patterns from RGB images for personal identification. Vessel tracing algorithms are of interest in a variety of biometric and medical application such as personal identification, biometrics, and ophthalmic disorders like vessel change detection. However eye surface vasculature tracing in RGB images has many problems which are subject to improper illumination, glare, fade-out, shadow and artifacts arising from reflection, refraction, and dispersion. The proposed algorithm on vascular tracing employs multi-stage processing of ten-layers as followings: Image Acquisition, Image Enhancement by gray scale retinal image enhancement, reducing background artifact and illuminations and removing interlacing minute characteristics of vessels, Vascular Structure Extraction by connecting broken vessels, extracting vascular structure using eight directional information, and extracting retinal vascular structure, and Vascular Landmark Extraction by extracting bifurcations and ending points. The results of automatic retinal vessel extraction using jive different thresholds applied 34 eye images are presented. The results of vasculature tracing algorithm shows that the suggested algorithm can obtain not only robust and accurate vessel tracing but also vascular landmarks according to thresholds.

• Journal of Korean Neurosurgical Society
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• v.40 no.1
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• pp.28-30
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• 2006

Two patients presented with amaurosis fugax[AMF]. despite treatment with antiplatelet drugs and anticoagulants due to previous transient ischemic attacks. Angiography demonstrated severe stenosis in the cavernous and petrous internal carotid artery[ICA] respectively, with reduced flow in the ophthalmic artery[OA]. Endovascular stent placement in both patients resulted in normalization of the vessel lumen of the stenotic vessel segments. In addition, complete restoration of OA flow was noted immediately after stenting. Both patients showed no further episode of AMF over a follow-up period of 38 and 23 months respectively. Our clinical and angiographic findings suggest that hemodynamic Insufficiency in retinal vasculature caused by a stenosis of the cavernous or petrous ICA can be treated successfully by endovascular stent.

• Journal of Computing Science and Engineering
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• v.8 no.2
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• pp.119-128
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• 2014

The appearance of retinal blood vessels is an important diagnostic indicator of serious disease, such as hypertension, diabetes, cardiovascular disease, and stroke. Automatic segmentation of the retinal vasculature is a primary step towards automatic assessment of the retinal blood vessel features. This paper presents an automated method for the enhancement and segmentation of blood vessels in fundus images. To decrease the influence of the optic disk, and emphasize the vessels for each retinal image, a multidirectional morphological top-hat transform with rotating structuring elements is first applied to the background homogenized retinal image. Then, an improved multiscale line detector is presented to produce a vessel response image, and yield the retinal blood vessel tree for each retinal image. Since different line detectors at varying scales have different line responses in the multiscale detector, the line detectors with longer length produce more vessel responses than the ones with shorter length; the improved multiscale detector combines all the responses at different scales by setting different weights for each scale. The methodology is evaluated on two publicly available databases, DRIVE and STARE. Experimental results demonstrate an excellent performance that approximates the average accuracy of a human observer. Moreover, the method is simple, fast, and robust to noise, so it is suitable for being integrated into a computer-assisted diagnostic system for ophthalmic disorders.