Bilateral intersection syndrome
This number is likely to more than double by according to the projection of WHO. This more than twofold global increase will occur because of population ageing and growth, as well as from obesity, unhealthy diets and a sedentary lifestyle.
These latter factors are closely associated with urbanization and industrialization. Other complications of diabetes include infections, metabolic difficulties, impotence, autonomic neuropathy and pregnancy problems.
Diabetic microvascular complications result from damage to the small blood vessels in the nerves, eyes and kidneys, and eventually lead to loss of function in these tissues. The walls of the vessels become abnormally thick but weak, followed by bleeding, leakage of protein which slows the flow of blood to the cells.
If undetected and untreated, these complications can potentially lead to severe organ damage possibly resulting in bilateral intersection syndrome amputation, blindness, and kidney failure. When the kidneys are damaged, protein leaks out of the kidneys into the urine. Damaged kidneys can no longer remove waste and extra fluids from the bloodstream. Overt nephropathy is characterized by 2, 3 progressive bilateral intersection syndrome in renal function resulting in end stage renal disease.
Neuropathy is a heterogenious condition that is associated with nerve pathology. The three major forms in people with diabetes are peripheral neuropathy, autonomic neuropathy, and mononeuropathy. The most common form is peripheral neuropathy, which affects mainly 2, 3 In the bilateral intersection syndrome, diabetes may affect almost all anatomical structures: diabetic keratopathy may develop, cataract formation is more rapid and the retina may suffer severe damage 2, 4 leading to the decline and finally the loss of vision.
The most serious eye condition associated with diabetes involves the retina and more specifically, the network of blood vessels lying within it. The abnormalities that characterise diabetic retinopathy occur in predictable progression with minor variations in the order of their appearance. Diabetic retinopathy is considered to be the result of vascular changes in the retinal circulation.
In the early stages vascular occlusion and dilations occur. It progresses into a proliferative retinopathy with the growth of new blood vessels. Macular edema the thickening of the central part of the retina can significantly decrease visual acuity. Figure 1. Color fundus image left and Fluorescein Angiography FLA late phase image right of an eye with moderate diabetic retinopathy bilateral intersection syndrome severe diabetic maculopathy. On the color fundus image retinal hemorrhages and microaneurysms can be seen, while the bilateral intersection syndrome hard exudates are indicative of diabetic macular edema.
On the late phase of the FLA diffuse leakage can be seen in the macula with several microaneurysms scattered around the entire retina.
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Specifically, diabetic maculopathy is very common in people with more térdfájdalom kórház background DRP. In diabetic maculopathy, fluid rich in fat and cholesterol leaks out of damaged vessels. If the fluid accumulates near the center of the retina the macula there will be distortion of central vision. If too much fluid and cholesterol accumulates in the macula, it can cause permanent loss of central vision.
Howewer, one of the main lehetséges kezelni a beteg ízületeket in routine clinical assessment of diabetic maculopathy is for quantitative parameters, also as an objective basis for assessing the efficacy of therapy.
The Early Treatment Retinopathy Study ETDRS criteria for classification of macular edema are based on slit-lamp biomicroscopy of macular thickening, independently of the angiographic findings.
- Dr. Gábor Márk Somfai - Semmelweis Egyetem Doktori Iskola
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This classification arose from the need for quantification, but is still not a complete solution, since bilateral intersection syndrome it only distinguishes between two major types of macular edema: Clinically Significant Macular Edema CSME and non-CSME. This is one of the main reasons bilateral intersection syndrome ophthalmic imaging techniques are developing so incredibly fast, enabling the assessment of more and more details down to a single photoreceptor cell.
Optical coherence tomography OCT is one of the fields where state-of-the-art technology meets clinical demands, helping the clinician ophthalmologist with a new dimension of medical thinking: the high resolution cross-sectional plane of the retina.
Thus, the longitudinal location of tissue structures are determined by measuring the time-of-flight delays of light backscattered from these structures.
The optical delays are measured by low coherence interferometry. Light reflected from deeper layers has a longer propagation delay than light reflected from more superficial layers. Low coherence means that the system employs a wide range of wavelengths. The most straightforward and currently the most bilateral intersection syndrome interferometer for OCT is a simple Michelson interferometer see Fig.
Light retro-reflected from the reference and the sample is recombined at the beam splitter and half is collected by a photodetector in the detection bilateral intersection syndrome of the interferometer. Half of the light is returned towards the source, where it is lost. In addition, the reference arm light is typically attenuated by orders of magnitude in order to improve signal to noise ratio.
Schematic drawing of the principle of OCT emphasizing how it is essentially a Michelson interferometer.
Dr. Gábor Márk Somfai - Semmelweis Egyetem Doktori Iskola
The outgoing light paths are solid lines, while reflected light is drawn as dashed lines. The axial resolution of an OCT image depends on the coherence length which is a fundamental property of the light source, whereas transverse resolution for OCT imaging is determined by focused spot size, as in microscopy. By rapidly varying the reference arm mirror and synchronously recording the magnitude of the resulting interference signal, a single axial profile or A-scan is obtained which is a graph of the optical reflectivity versus distance in the eye.
A sequence of such A-scans is obtained by scanning the probe beam across the entire retina which forms bilateral intersection syndrome B-scan tomogram. As a result, a cross-sectional view of the structure similar to a histology section is obtained. The method and also its display in originally greyscale pixels is very similar to that of ultrasound, with the exception that light is used for imaging purposes rather than light, leading to the above mentioned advantages of resolution resulting from a shorter wavelength.
OCT can be used for retinal imaging and anterior segment imaging.
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The OCT for ophthalmic examination is similar to a slit lamp for anterior segment imaging and a fundus camera for retinal imaging. The instrumentation includes a video display for operator viewing of the anterior segment or fundus while obtaining the OCT images and a simultaneous computer display of bilateral intersection syndrome tomograms. Images are stored via computer for the diagnostic record. Strong reflections occur 10 between two materials of different refractive indices bilateral intersection syndrome from a tissue that has a high scattering coefficient along with a disposition to scatter light in the perfectly backward direction.
In most tissues, main sources of reflection are collagen fiber bundles, cell walls, and cell nuclei. Dark areas on the image represent homogeneous material with low reflectivity, such as air or clear fluids. The imaging light is attenuated in the sample, so there is an exponential decrease in the intensity of the image with depth. Blood attenuates the signal faster than collagenous tissues, fat and fluids attenuate the signal the least.
OCT image of the normal human macula. A Ultrahigh resolution OCT image showing the various cellular layers of the retina. B Comparison of the OCT image same as shown in A to a histologic micrograph of the normal human macula. Image taken from ref. High backscatter appears red-orange and low backscatter appears blue-black see Fig. Thus, cellular layers with different reflectivity are displayed in different colors.
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- Роберт был разъярен.
- Тогда, быть может, вы, в качестве дополнения или приложения к документу о капитуляции, обещаете сохранить жизнь и безопасность октопауков и всех остальных существ, если они не будут нарушать законы, установленные на оккупированной вами территории.
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It is important to note that OCT image contrast arises from intrinsic differences in tissue optical properties. Thus, coloring of different structures represent different optical properties in false color image and it is not necessarily different tissue pathology see Fig. Warm colors red to bilateral intersection syndrome represent areas 11 of re lative high reflectivity, while cold colors blue to black represent areas of relative low reflectivity.
The exact relationship between the histology of the tissue and the OCT map is still under investigation. Layers with relatively high reflectivity correspond to areas of horizontal retinal elements such as the nerve fiber layer at the retinal surface and the retinal pigm ent epithelium RPE and choroid. Relatively low reflective layers correspond to the nuclear layers and a single layer of photoreceptor inner and outer segments.
A typical example of OCT images of the human macula for normal and pathologic eyes is shown in Figure 4, respectively. The OCT image shown in Fig. This image demonstrates thickening of the macula with several large hyporeflective cystoid spaces in the fovea. When comparing the image of the pathologic subject with the one obtained in the normal subject, the importance of quantifying the structural changes of retinal features and pathologies is obvious.
Figure 4. OCT images of the retina for a healthy bilateral intersection syndrome pathologic human eye.
A Image of the retina of a normal subject. Note that the fovea has a characteristic depression with thinning of the retina corresponding to its normal anatomy. B OCT image from a subject with cystoid macular edema caused by diabetes.
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- Прощайте, Женевьева, Симона и Кэти.
Note the thickening of the macula with several large hypo-reflective cystoid spaces in the central region. The OCT signal strength is represented in false color using the normal visible spectrum scale. High backscatter is represented by red-orange color and low backscatter appears blueblack. The retinal pigment epithelium RPE and choriocapillaris layer ChCap is visualized as a highly reflective red layer and represents the posterior boundary of the retina.
Below the choriocapillaris weakly scattered light returns from the choroid and sclera because of attenuation of the signal after passing through the neurosensory retina, RPE, and ChCap. The outer segments of the rods and cones appear as a dark layer of minimal reflectivity anterior to the RPE and ChCap. The intermediate layers of the retina exhibit moderate backscattering see Fig. The fovea appears as a characteristic thinning of the retina.
Retinal blood vessels are identified by their increased backscatter and by their blocking of the reflections from the RPE and ChCap see Fig. The larger choroidal vessels have minimally reflective dark lumens.
Below are summarized the OCT features that need to be observed carefully when interpre ting the result of a macular OCT image. Before reading it further, we would recom mend the Reader to look attentively at figures 4A and 8. A very important feature of the OCT system is that it provides information on the retinal structures.
For example, the location of fluid accumulation in bilateral intersection syndrome to the different retinal layers may be determined and the response to treatment without the need to perform invasive studies such as fluorescein angiography may be objectively monitored.
At the same time it may be possible to explain why some patients respond to treatment while others do not. OCT has significant potential both as a diagnostic tool and particularly as a way to mon itor objectively subtle retinal changes induced by therapeutic interventions.
Thus, OCT may become a valuable tool in determining the minimum maintenance dose of a certain drug in the treatment of retinal diseases, and may bilateral intersection syndrome retinal changes that explain the recovery in some patients without angiographically demonstrable improvement and lack of recovery In the clinical routine, measurement of retinal thickness by the OCT software depends on the identification of the internal limiting membrane and the hyper-reflective band believed to correspond to the retinal pigment epithelium — choriocapillaris interface or, more precisely, the photoreceptor inner-outer segment border in the case of third generation OCTs.
The OCT software calculates the distance between these 2 boundaries across all of the sampled points usually along 6 evenly spaced radial lines and interpolates the retinal thickness in the unsampled areas between these lines.
As a result, central retinal thickness in the foveal centre can be obtained, along with total macular volume in a 6. The Stratus OCT has an optional built-in normative database that is very reliable in detecting thickness bilateral intersection syndrome from the age-adjusted normal values.
Besides, there is a possibility to track thickness and volume changes by comparative analyses provided by the software. This enables the clinician to follow retinal changes as they bilateral intersection syndrome either naturally or as a response to therapy.
However, once the various layers can be identified and correlated with the histological structure of the retina, it may seem relevant to measure not only the entire thickness of the retina, but the thickness of the various cellular layers. Moreover, measuring the reflectance of the various retinal layers on OCT images may also be of interest.
Biokémiai és Molekuláris Biológiai Intézet
Thus, it also seems rational that quantitative analysis of reflectance changes may provide clinically relevant information in retinal pathophysiology. It is very important to emphasize that usually, image analysis quality largely depends upon the quality of the acquired signal itself. Thus, controlling and assessing the OCT image quality is of high importance to obtain the best quantitative and qualitative assessment of retinal morphology.
At present, the Stratus OCT software provides a quality score, identified as the signal strength SS but the clinical advantage of this parameter is not really known.
The quality score is bilateral intersection syndrome on the total amount of the retinal signal received by the OCT system. We note that the SS score should not be used as an image quality score since it is basically a signal strength score.
It was previously found that SS outperformed signal-to-noise ratio SNR in terms of poor image discrimination. Stein et al.
From our experience, if the best attainable image has a SS of less than 6 units, the potential for images to be missing valuable tissue information increases.
On the other hand, certain types of retinal pathology have a propensity to generate poorer quality images and it is difficult to determine whether or not these pathological images are of poor quality, or if these are the best possible quality images that can be bilateral intersection syndrome bilateral intersection syndrome an eye with advanced retinal damage. During the course of scanning patients in our clinics, we have observed several different types of scan artifacts.
Some of these artifacts have been 15 observed previously, 13, 20 and have been also analyzed in a systematic manner For example, due to the operator pitfall's errors, the Stratus OCT custom built-in algorithm may fail to locate properly the inner and outer boundaries of the retina see Fig.
Since these boundaries are found by a threshold procedure, their estimated locations could be sensitive to relative differences in reflectance between the outer and deeper retinal structures. Bilateral intersection syndrome, even scans of normal eyes could have inner and outer retina misidentification artifacts under operator errors. Figure 5.