A Method for Chorioretinal Oxygen Tension Measurement

Shahidi, Mahnaz; Shakoor, Akbar; Blair, Norman P.; Mori, Marek; Shonat, Ross D.

doi:10.1080/02713680600599446

Cited by 47 publications

(54 citation statements)

References 41 publications

(50 reference statements)

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“…The instrument used for measurements of PO 2 separately in the retinal and choroidal vasculatures has been described previously [27] . A laser beam ( = 532 nm) was projected at an oblique angle on the retina following intravenous injection of the probe, and phosphorescence emission was imaged.…”

Section: Imagingmentioning

confidence: 99%

“…In each eye, phase-delayed images were acquired by varying the phase relationship between the two modulators. The images were analyzed to derive phosphorescence lifetime in the retinal vein, artery, capillaries, and in the choroid [27] . The phosphorescence lifetime measurements were converted to provide measurements of PO 2 , according to the Stern-Volmer expression:…”

Section: Imagingmentioning

confidence: 99%

“…Rectal temperature was maintained between 37 and 38 ° C via a copper tubing water heater. An oxygen-sensitive molecular probe, either Pd-porphyrin (Frontier Scientific, Logan, Utah, USA) or Oxyphor R2 (Oxygen Enterprises, Philadelphia, Pa., USA), was prepared and injected intravenously [27] . Initially, Pd-porphyrin was used in 22 animals and later Oxyphor R2, which is a formulation of the Pd-porphyrin that is simpler to prepare, was used in 7 animals.…”

Section: Animalsmentioning

confidence: 99%

“…We have previously developed a method to measure PO 2 separately in the chorioretinal vasculatures noninvasively with respect to the eye [25][26][27] . The purpose of the current study was to establish the variability and baseline measurements of intravascular chorioretinal PO 2 in spontaneously breathing, anesthetized rats.…”

mentioning

confidence: 99%

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Chorioretinal Vascular Oxygen Tension in Spontaneously Breathing Anesthetized Rats

et al. 2007

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Purpose: To establish baseline and variability of oxygen tension (PO₂) measurements in the choroid, retinal arteries, capillaries, and veins of spontaneously breathing anesthetized rats and determine the effect of a moderate surgical procedure on the chorioretinal PO₂. Methods: Our previously established optical section phosphorescence imaging technique was utilized to measure PO₂ in the chorioretinal vasculatures. Imaging was performed in 29 spontaneously breathing rats under ketamine/xylazine anesthesia. In 7 rats, blood was drawn using a surgically implanted femoral arterial catheter and analyzed to determine the systemic arterial PO₂. The PO₂ measurements in 22 rats without surgery (group 1) and 7 surgically instrumented rats (group 2) were statistically compared. The intrasubject variability was calculated by the average standard deviation (SD) of repeated measurements. Results: The average systemic arterial PO₂ was 52 ± 7 mm Hg (mean ± SD) in group 2. In group 1, the average PO₂ measurements in the choroid, retinal arteries, capillaries, and veins were 50 ± 11, 40 ± 5, 39 ± 6, and 30 ± 5 mm Hg, respectively. No statistically significant PO₂ differences in any of the chorioretinal vasculatures were found between the two groups (p > 0.4). The intrasubject variability was 3 mm Hg in the choroid, retinal arteries, capillaries, and veins. Conclusions: Chorioretinal PO₂ measurements in spontaneously breathing anesthetized rats have a relatively low variability, indicating that PO₂ changes due to various physiological alterations can be reliably assessed.

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Section: Imagingmentioning

confidence: 99%

Section: Imagingmentioning

confidence: 99%

Section: Animalsmentioning

confidence: 99%

mentioning

confidence: 99%

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Chorioretinal Vascular Oxygen Tension in Spontaneously Breathing Anesthetized Rats

et al. 2007

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“…It was observed that phosphorescencelifetimes were directly dependent on oxygen concentration, with an increase in phosphorescence signal as PO 2 decreased, as described by a Stern-Volmer relationship [92,93]. This technique was modified for use in vivo to measure PO 2 in the retinal and choroidal vasculature of large animals such as cats and pigs [95][96][97], and later for smaller animals such as mice and rats [98][99][100][101][102][103][104]. More recently Shahidi et al have made significant advances by using phosphorescence-lifetime to image oxygen tension within the retinal tissue itself [105,106].…”

Section: Phosphorescence-lifetime Imagingmentioning

confidence: 99%

Imaging of Hypoxia in Retinal Vascular Disease

Feenstra¹,

Drawnel²,

Jayagopal³

2018

Early Events in Diabetic Retinopathy and Intervention Strategies

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Retinal tissue hypoxia is a key mediator in the pathogenesis of many leading causes of irreversible vision loss, including diabetic retinopathy. Retinal hypoxia in diabetic retinopathy has been shown to drive the production of pro-inflammatory cytokines and pro-angiogenic growth factors. Together, these factors contribute to disease progression by causing unregulated growth of new blood vessels, increased vascular permeability and cell death within the retina. Studies have shown that retinal hypoxia precedes many of the pathologic events that occur during the progression of diabetic retinopathy such as angiopathy, microaneurysms, and capillary dropout. Therefore, early detection of hypoxia in the retinas of diabetic patients could help clinicians identify problems in patients before irreversible damage has occurred. Currently, oxygen sensitive electrodes remain the gold standard for direct measurement of oxygen tension within the retinal tissue; however the procedure is highly invasive and is therefore limited in its applicability towards preclinical models. Less invasive techniques such as retinal oximetry, phosphorescence-lifetime imaging, and hypoxia-sensitive fluorescent probes have shown promising diagnostic value in facilitating detection of oxygen imbalance correlated with neurovascular dysfunction in DR patients. This review highlights the current progress and potential of these minimally invasive hypoxia-imaging techniques in diabetic retinopathy.

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Role of Endothelial Cell and Pericyte Dysfunction in Diabetic Retinopathy: Review of Techniques in Rodent Models

Chou¹,

Rollins²,

Fawzi³

2014

Advances in Experimental Medicine and Biology

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Diabetic Retinopathy is one of the hallmark microvascular diseases secondary to diabetes. Endothelial cells and pericytes are key players in the pathogenesis. Interaction between the two cell types is important in the regulation of vascular function and the maintenance of the retinal homeostatic environment. There are currently several approaches to analyze changes in morphology and function of the two cell types. Morphologic approaches include trypsin digest, while functional approaches include studying blood flow. This review explores the advantages and limitations of various methods and summarizes recent experimental studies of EC and pericyte dysfunction in rodent models of DR. An improved understanding of the role played by EC and pericyte dysfunction can lead to enhanced insights into retinal vascular regulation in DR and open new avenues for future treatments that reverse their dysfunction.

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A Method for Chorioretinal Oxygen Tension Measurement

Cited by 47 publications

References 41 publications

Chorioretinal Vascular Oxygen Tension in Spontaneously Breathing Anesthetized Rats

Chorioretinal Vascular Oxygen Tension in Spontaneously Breathing Anesthetized Rats

Imaging of Hypoxia in Retinal Vascular Disease

Role of Endothelial Cell and Pericyte Dysfunction in Diabetic Retinopathy: Review of Techniques in Rodent Models

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