Quant BV’s application is specifically demonstrated in the analysis of retinal images. The eyes are the only part of the body through which blood vessels can be directly visualized non-invasively in humans and animals through the pupil, allowing acquisition of digital images. These digital images can be quantitatively analyzed for various vascular parameters with Quant BV for research clinical purposes. Histological images of the retina can also be analzyed using Quant BV.
Sample research applications include:
- Retinopathy of Prematurity (ROP)
- Animal models of Oxygen-Induced Retinopathy (OIR)
- Diabetic Retinopathy
- Ischemic Retinopathies
- Retinal Vascular Occlusions
- Macular Degeneration
- Retinal Fluorescein Angiography
- Proliferative Retinopathies
QuantBV Application in Retinopathy of Prematurity (ROP)
Premature infants are born early in gestation and therefore their fragile, developing blood vessels are exposed to harsh external stimuli, exacerbated by the use of oxygen for the immature lungs. Hyperoxia (high oxygen environment) disrupts blood vessel development in the retina, resulting weeks later to pathologic neovascularization, bleeding and retinal detachment, leading to a condition called Retinopathy of Prematurity (ROP). ROP is one of the leading causes of childhood blindness worldwide.
Animal models of disease, especially oxygen-induced retinopathy (OIR) are commonly used to study human retinal diseases. In ROP, the OIR mouse model involves exposure of one week old newborn mice to hyperoxia for five days and returning them to room air, (1) while the OIR rat model exposes newborn rats to alternating hyperoxia and hypoxia for 14 days before return to room air. (2) Subsequently, the retina can be extracted and retinal whole mounts performed with staining to visualize vessels. Images of the flattened retina can be quantitatively analyzed using Quant BV. In vivo fluorescein angiography (FA) can be performed on live, anesthetized animals following OIR, and directly visualized using a retinal imaging device. (3) Still images or videos acquired during FA can be analyzed with Quant BV. Following OIR, in vivo FA shows distinct phenotypical features in arteries, veins and capillaries, which can be quantitatively analyzed. (3) In the mouse OIR model, the retinal arteries are noted to be tortuous and retinal veins appear larger in width in oxygen exposed compared to room air mice.
Quant BV is a customized, statistically validated objective method for quantitative analysis of the vascular features seen in vivo or in ex vivo images. The image analysis with Quant BV allows the study of physiology and pathologic properties of the tissues, as well as longitudinal monitoring of disease processes and the effect of therapies. Quant BV program allows real time or longitudinal analysis of the following retinal vascular parameters:
- Automated quantification of percent of Retinal Vascular Area (RVA): RVA defines the area of the retinal image covered by all vessels
- Automated and Semi-automated quantification Retinal Vein Width (RVW): RVW defines the width or diameter of the retinal vein.
- Automated and Semi-automated quantification Retinal Arterial Tortuosity (RAT): RAT defines the tortuosity of the retinal artery.
RVA, RVW, and RAT can be compared in an image of a diseased retina relative to a normal retina.(3) Quant BV data generated is automatically saved to an excel spreadsheet that allows export to other statistical programs for further analysis.
References:
- Smith LE, Wesolowski E, McLellan A, Kostyk SK, D’Amato R, Sullivan R, D’Amore PA. Oxygen-induced retinopathy in the mouse. Invest Ophthalmol Vis Sci 1994;35:101-11.
- Penn JS, Henry MM, Wall PT, Tolman BL. The range of PaO2 variation determines the severity of oxygen-induced retinopathy in newborn rats. Invest Ophthalmol Vis Sci 1995:36(10):2063-70
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Mezu-Ndubuisi, Olachi J. In Vivo Angiography Quantifies Oxygen-Induced Retinopathy Vascular Recovery. Optometry & Vision Science 2016: 93 (10).