Color Doppler Imaging of Choroidal Circulation in Patients with Asymmetric Age-Related Macular Degeneration

Üretmen, Önder; Akkin, Cezmi; Erakgün, Tansu; Killi, Refik

doi:10.1159/000068559

Cited by 31 publications

(13 citation statements)

References 29 publications

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“…[51][52][53] The results of one of those studies suggested that irregular blood flow in the short posterior ciliary arteries may play a role in the pathogenesis of exudative ARMD. 51 There have been reports on the effect of various forms of treatment of exudative ARMD to the retrobulbar circulation.…”

Section: -53mentioning

confidence: 99%

Colour Doppler Imaging of Ocular and Orbital Blood Vessels in Retinal Diseases

Dimitrova¹

2011

European Ophthalmic Review

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ImagingColour Doppler Imaging (CDI) is an established method for investigation of the ocular and orbital blood flow characteristics. It is an ultrasonographic method that has been employed for the evaluation of the circulatory status in much ocular pathology, but is most used for the investigation of the circulatory status in retinal vascular disorders and in glaucoma. [1][2][3] Ultrasound imaging (sonography) is accomplished with a pulse-echo technique. Pulses of ultrasound (generated by a transducer) are sent into the patient where they produce echoes at organ boundaries and within tissues. These echoes then return to the transducer, they are being detected and then displayed. Colour-flow imaging extends the use of the pulse-echo imaging principle. Echoes returning from stationary tissues are detected and presented in greyscale in appropriate locations along the scan line. The depth is determined by the echo's arrival time and the brightness is determined by the echo's amplitude. If a returning echo has a different frequency than what is emitted a frequency change has occurred because the echo-generating object was moving. If the motion is towards or away from the transducer, the Doppler shift is positive or negative, respectively. Along with the transducer, the colour-flow instrument consists of a pulser, a beam-former, a receiver, a memory and a display (see Figure 1).In ophthalmology, CDI is most often used to study the circulatory parameters in the retrobulbar blood vessels -the central retinal artery, central retinal vein, ophthalmic artery and the short and long posterior ciliary arteries. However, intraocular blood vessels have also been studied, such as vortex veins, blood vessels in the intraocular tumours, in detached retina, etc. The measurement is usually obtained through closed eyelids in a supine or in a seated position. Nagahara et al.patented a device for CDI measurement in seated subjects that increased the reproducibility of the measurement by 50% (see Figure 2). 4 The reflected ultrasound from the moving cells in the measured blood vessels is recorded by the CDI device and represented as a velocity wave. Two such velocity waves from the central retinal artery and the central retinal vein are presented in Figure 3.Several blood flow parameters can be obtained from the velocity wave, such as peak systolic blood velocity (PSV), end-diastolic blood velocity (EDV), mean blood velocity (MV), resistivity index (RI) and pulsatility index (PI): RI is calculated as (PSV-EDV)/PSV; PI is calculated as (PSV-EDV)/MV.Although the CDI device is equipped for measurement of blood vessel diameter, the dimension of the retrobulbar blood vessels is too small to obtain a reliable estimation of their diameter. Therefore, total blood flow cannot be evaluated in the retrobulbar blood vessels using CDI.The recording of the blood flow parameters of the central retinal artery and vein is obtained inside the optic nerve, a few millimetres away from the lamina cribrosa (see Figure 3). A specific finding of the blood flo...

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Section: -53mentioning

confidence: 99%

Colour Doppler Imaging of Ocular and Orbital Blood Vessels in Retinal Diseases

Dimitrova¹

2011

European Ophthalmic Review

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“…Although it has been reported that patients with unilateral CNV have reduced posterior ciliary artery flow velocities in both eyes, 79 other investigators have found that posterior ciliary artery blood velocities are more affected in the exudative eye than in the contralateral eye. 80 Another approach to studying the choroidal vasculature in AMD is based on angiographic techniques, although the extraction of quantitative data from the choroids based on angiograms is still difficult. However, a number of studies have characterized abnormalities in the choroidal circulation based on angiograms in patients with AMD.…”

Section: Degenerationmentioning

confidence: 99%

Ocular blood flow in diabetes and age-related macular degeneration

Pemp

Schmetterer

2008

Canadian Journal of Ophthalmology

144

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“…It was further postulated that removal of waste materials and the supply of nutritional substances as well as oxygen exchange to the neural retina is impaired due to choroidal vascular alterations [34]. In several studies using different techniques it has been shown that reduced choroidal blood flow is associated with AMD [35][36][37][38]. This theory is supported by correlation of AMD with diseases involving arteriosclerotic changes such as the carotid artery disease [38].…”

Section: Choroidal Circulation Theorymentioning

confidence: 99%

“…In several studies using different techniques it has been shown that reduced choroidal blood flow is associated with AMD [35][36][37][38]. This theory is supported by correlation of AMD with diseases involving arteriosclerotic changes such as the carotid artery disease [38]. Interestingly, most epidemiological studies, except for the Rotterdam Study [39], did not find a direct association of cardiovascular disease and AMD [40][41][42], however many factors for cardiovascular disease are also risk factors for AMD.…”

Section: Choroidal Circulation Theorymentioning

confidence: 99%

Nutrition and Retina

Schmidt‐Erfurth¹

2005

Developments in Ophthalmology

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The impact of nutrition on manifestation and progression of retinal diseases has become an important, controversial topic within recent years. The awareness of this topic in the general population has increased partially due strong commercial advertisements of supplements and diets. However, many potentially beneficial nutritional effects on retinal diseases have not been proven in prospective clinical trials. It is only for a few relatively rare diseases, such as retinitis pigmentosa or gyrate atrophy, that adjustments in nutrition have been proven effective and widely accepted. However, for the majority of patients with retinal diseases the impact of nutritional factors is still insufficiently understood. Theoretically, supplementation of antioxidants could have a beneficial impact on a wide variety of retinal diseases or as a preventive measure by limiting the degree of oxidative damage. The only prospective, controlled, clinical trial providing proven benefit of antioxidant supplementation for a retinal disease is the Age-Related Eye Disease Study (AREDS). Patients with at least intermediate age-related macular degeneration (AMD) were shown to have a significant benefit with regard to disease progression by supplementing with high-dose antioxidants and zinc. It is however unclear whether other antioxidants, such as lutein or zeaxanthin, may be better and whether a preventive supplementation is useful. Especially studies on patients with diabetic retinopathy have implicated an impact of higher cholesterol levels on the progression of the disease. High-fat diets have been overall associated to a number of retinal diseases. With the current knowledge it seems prudent to advise everyone a balanced, low-fat diet as well as vitamin supplementation within the recommended daily allowance. Smoking is an essential factor for oxidative stress, and its cessation should be recommended to everybody in order to prevent or slow down progression of retinal disease. High-dose antioxidant supplementation according to the AREDS trial should currently only be recommended to non-smokers with at least intermediate AMD. Based on results from experimental studies, further prospective clinical studies are warranted on the prevention and inhibition of disease progression in the most common retinal diseases by nutritional means.

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Color Doppler Imaging of Choroidal Circulation in Patients with Asymmetric Age-Related Macular Degeneration

Cited by 31 publications

References 29 publications

Colour Doppler Imaging of Ocular and Orbital Blood Vessels in Retinal Diseases

Colour Doppler Imaging of Ocular and Orbital Blood Vessels in Retinal Diseases

Ocular blood flow in diabetes and age-related macular degeneration

Nutrition and Retina

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