It is clear that DME affects macular structure in both the short and long term. While visual loss occurs when macular edema involves the visual center, lesser degrees of DME may cause visual deterioration. This definition of CSME generally refers to the threshold level at which laser photocoagulation treatment is considered. Clinically significant macular edema (CSME) occurs if there is thickening of the retina involving the center of the retina (macula) or the area within 500 m of the center, if there are hard exudates at or within 500 m of the center with thickening of adjacent retina, or if there is a zone of retinal thickening one optic disc area or larger in size, any part of which is within one disc diameter of the center of the retina. The breakdown of the blood-retinal barrier causes leakage of dilated hyperpermeable capillaries and microaneurysms into intracellular and extracellular retinal tissue with subsequent fluid accumulation. The primary cause of visual loss in people with diabetes is DME, which is more common in type 2 diabetes. As such, the methods presented are expected to influence routine clinical patient care in the years to come.īreakdown of the blood-retinal barrier, leading to fluid leakage, diabetic macular edema (DME) and damage to photoreceptors. ![]() The described methods cover the developments of the past decade and were selected with respect to their potential for screening-motivated computer-aided detection of retinal abnormalities as well as for translational clinical applications including improved retinal disease diagnoses and image-guided retinal therapy. Special emphasis is given to fundus and optical coherence tomography (OCT) image analysis and its use to provide comprehensive descriptions of retinal morphology and function. Principles of 2-D and 3-D retinal imaging are outlined first. This review focuses on quantitative approaches to retinal image analysis. Thus, on the one hand, the retina is vulnerable to organ-specific and systemic diseases, while on the other hand, imaging the retina allows diseases of the eye proper, as well as complications of diabetes, hypertension and other cardiovascular diseases, to be detected, diagnosed and managed. Complications of such systemic diseases include diabetic retinopathy from diabetes, the second most common cause of blindness in the developed world, hypertensive retinopathy from cardiovascular disease, and multiple sclerosis. A number of systemic diseases also affect the retina. These include ocular diseases, such as macular degeneration and glaucoma, the first and third most important causes of blindness in the developed world. Thus, because of its architecture-dictated by its function-both diseases of the eye, as well as diseases that affect the circulation and the brain can manifest themselves in the retina. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships.įirst known image of human retina as drawn by Van Trigt in 1853. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. ![]() Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Many important eye diseases as well as systemic diseases manifest themselves in the retina.
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