Functional imaging using the retinal function imager: Direct imaging of blood velocity, achieving fluorescein angiography-like images without any contrast agent, qualitative oximetry, and functional metabolic signals

Izhaky, David; Nelson, D. A.; Burgansky-Eliash, Zvia; Grinvald, Amiram

doi:10.1007/s10384-009-0689-0

Cited by 66 publications

(63 citation statements)

References 33 publications

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“…6 In brief, the device calculates the crosscorrelation of moving patterns of erythrocytes and single erythrocytes over eight consecutive pictures and quantifies the RBFV of venules and arterioles.…”

Section: Rfi Measurementsmentioning

confidence: 99%

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Blood flow velocity measured using the Retinal Function Imager predicts successful ranibizumab treatment in neovascular age-related macular degeneration: early prospective cohort study

Böhni

Howell

Bittner

et al. 2015

Eye

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Purpose Anti-VEGF treatment has a potent vasoconstrictive effect. Early changes of retinal blood flow velocity (RBFV) measured using the Retinal Function Imager (RFI) combined with indicators of vascular status may help in predicting the visual outcome 1 month post injection in patients with neovascular age-related macular degeneration (nvAMD) under ranibizumab treatment. To develop a simple prediction model based on the change in RBFV 3 days post injection and indicators of a patient's vascular status to assess the probability of a successful visual outcome 1 month post injection.Methods RBFV measured using RFI were prospectively collected pre-injection and 3 days post injection in 18 eyes of 15 patients. Indicators of vascular status (history of hypertension, diabetes mellitus without retinal affection, and smoking) were assessed by medical history. By univariate analyses, parameters associated with visual outcome were weighted (−1 to 6 points). A multivariate logistic regression model with the categorized visual outcome parameter (≥0 letters gained after 1 month) as the dependent variate and the sum score as the independent variate (continuous scale) was used to estimate the score value-specific probabilities of letters gained ≥ 0 1 month post injection. Results The indicators of vascular status negatively influenced the likelihood of a letter gain ≥ 0 whereas an increase in the arterial RBFV strongly increased it. The area under the receiver operating characteristics curve for these parameters investigated was 0.71 (95% CI: 0.43-1.00). Conclusion Changes in the arterial RBFV following 3 days after ranibizumab injection combined with three indicators of the vascular status identified nvAMD patients with favorable visual outcome accurately.

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Section: Rfi Measurementsmentioning

confidence: 99%

“…[6][7][8] The RBFV is measured by direct observation of erythrocyte movement. The RFI has proven to be a valuable tool in investigating various retinal conditions [9][10][11][12][13][14][15][16] as well as in evaluating the medical treatment.…”

Section: Introductionmentioning

confidence: 99%

Blood flow velocity measured using the Retinal Function Imager predicts successful ranibizumab treatment in neovascular age-related macular degeneration: early prospective cohort study

Böhni

Howell

Bittner

et al. 2015

Eye

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“…1,2 Various approaches have been used to assess in vivo microvascular oxygen saturation, including oxygen-sensitive microelectrodes, [3][4][5][6][7] magnetic resonance imaging (MRI), [8][9][10][11][12] reflection spectroscopic oximetry. [13][14][15][16][17][18] and phosphorescence quenching. 17,[19][20][21][22][23][24] Measurement by oxygen-sensitive microelectrodes is a point measurement method and is primarily limited to animal studies.…”

Section: Introductionmentioning

confidence: 99%

Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation

Yin

Kuranov²,

McElroy

et al. 2013

J. Biomed. Opt

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Abstract. A swept-source dual-wavelength photothermal (DWP) optical coherence tomography (OCT) system is demonstrated for quantitative imaging of microvasculature oxygen saturation. DWP-OCT is capable of recording three-dimensional images of tissue and depth-resolved phase variation in response to photothermal excitation. A 1,064-nm OCT probe and 770-nm and 800-nm photothermal excitation beams are combined in a single-mode optical fiber to measure microvasculature hemoglobin oxygen saturation (SO 2 ) levels in phantom blood vessels with a range of blood flow speeds (0 to 17 mm∕s). A 50-μm-diameter blood vessel phantom is imaged, and SO 2 levels are measured using DWP-OCT and compared with values provided by a commercial oximeter at various blood oxygen concentrations. The influences of blood flow speed and mechanisms of SNR phase degradation on the accuracy of SO 2 measurement are identified and investigated.

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“…Briefly, we acquired retinal images using a Retinal Function Imager (RFI) that applies fundus illumination with predominantly green component to highlight blood vessels (Grinvald et al, 2004;Izhaky et al, 2009). We acquired each image using a 20-degree aperture camera, focused on the fovea and with a resolution of 4.27 micron/pixel.…”

Section: Image Acquisitionmentioning

confidence: 99%

Algorithm for predicting macular dysfunction based on moment invariants classification of the foveal avascular zone in functional retinal images

Arthur

Silva

et al. 2017

Res. Biomed. Eng.

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Introduction: A new method for segmenting and quantifying the macular area based on morphological alternating sequential filtering (ASF) is proposed. Previous studies show that persons with diabetes present alterations in the foveal avascular zone (FAZ) prior to the appearance of retinopathy. Thus, a proper characterization of FAZ using a method of automatic classification and prediction is a supportive and complementary tool for medical evaluation of the macular region, and may be useful for possible early treatment of eye diseases in persons without diabetic retinopathy. Methods: We obtained high-resolution retinal images using a non-invasive functional imaging system called Retinal Function Imager to generate a series of combined capillary perfusion maps. We filtered sequentially the macular images to reduce the complexity by ASF. Then we segmented the FAZ using watershed transform from an automatic selection of markers. Using Hu's moment invariants as a descriptor, we can automatically classify and categorize each FAZ. Results: The FAZ differences between non-diabetic volunteers and diabetic subjects were automatically distinguished by the proposed system with an accuracy of 81%. Conclusion: This is an innovative method to classify FAZ using a fully automatic algorithm for segmentation (based on morphological operators) and for the classification (based on descriptor formed by Hu's moments) despite the presence of edema or other structures. This is an alternative tool for eye exams, which may contribute to the analysis and evaluation of FAZ morphology, promoting the prevention of macular impairment in diabetics without retinopathy.

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Functional imaging using the retinal function imager: Direct imaging of blood velocity, achieving fluorescein angiography-like images without any contrast agent, qualitative oximetry, and functional metabolic signals

Cited by 66 publications

References 33 publications

Blood flow velocity measured using the Retinal Function Imager predicts successful ranibizumab treatment in neovascular age-related macular degeneration: early prospective cohort study

Blood flow velocity measured using the Retinal Function Imager predicts successful ranibizumab treatment in neovascular age-related macular degeneration: early prospective cohort study

Dual-wavelength photothermal optical coherence tomography for imaging microvasculature blood oxygen saturation

Algorithm for predicting macular dysfunction based on moment invariants classification of the foveal avascular zone in functional retinal images

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