Human eye plays a vital role in vision. Eye reacts with the light and sense the vision. Visual perception is important in human life. Hence, detecting and diagnosing eye disease in the earlier stage is necessary. Diabetic retinopathy is an eye disease in which the retina structure of an eye gets affected which is caused due to diabetes. By digital processing the retinal images, we can have a computer assisted diagnosis of diabetic retinopathy. Feature extraction plays a vital role for computer aided DR detection. The features like blood vessel, exudate and hemorrhage can be extracted from retinal fund us images.
Mainly we have five sense organs and it is eye which allow us to learn and understand more about the surrounding world when compared with other sense organs. And it is clear that eye is one of the most important organ for sense of sight. We perceive up to 80 percentage of all impressions by means of our sight. We use our eyes in almost every activities like reading articles, watching television, and in many other endless ways. It will be very difficult to do our daily activities if we have no vision capability. Diabetic retinopathy is a medical condition which effect eyes and can cause blindness.
Diabetic retinopathy which is other vice known as diabetic eye disease, is a condition which occurs due to the damage in retinal blood vessels. People with diabetes have more prob-ability to occur diabetic retinopathy. Retinal blood vessels get damaged due to the increased blood sugar level. These retinal blood vessels can swell and leak. Or they can close, stopping blood from passing through the tissues in retina. Sometimes new blood vessels may grow abnormally in the retina. All of these changes can steal your vision.
By processing the light that the object reflect or emit, the eye allows us to see and interpret the shapes, colors, and dimensions of objects in the world. The eye is able to see the object clearly in bright light and difficult in dim light, but it cannot see objects when there is no light. Vision occurs when the brain interprets light which is reflected from an object. The light enters the cornea through pupil, which is located in the middle of the iris and it is a colored membranous disk that is composed of two types of muscular fibers.
Stages of diabetic retinopathy can be classified into mainly3 stages. These stages are defined by pathology not bysymptoms:
In the earliest stages of disease, there can be loss of retinal capillary pericytes, which may contributes to the mechanical changes in the retinal blood vessels, altering their patency and permeability. These changes consist of micro aneurysms (i.e. focal dilations) of retinal capillaries located in the inner nuclear layer that can be appreciated by the direct ophthalmoscope as tiny red dots about the size of a pinhead in the retina. It is Hyperglycemia (high blood sugar level) that causes damage to pericyte cells within the retina. These pericytes are important for regular blood flow within the retina. The excess glucose that is not properly metabolized will results in osmotic damage.
It is the second stage, non-proliferative diabetic retinopa-thy (NPDR),and this stage has no symptoms. Its signs aren’t visible to the eye and patients will have 20/20 vision. Fund us photography is the only way to detect NPDR, in which micro aneurysms (microscopic blood-filled bulges in the artery walls) can be seen. If there is reduced vision, fluoresce in angiography can show the back of the eye and narrowing or blocked retinal blood vessels clearly. This is called retinal ischemia (lack of blood flow). Macular edema, is a condition in which blood vessels leak their contents into the macular region. This can occur at any stage of NPDR. Its symptoms include blurred vision and darkened or distorted images that are not the same in both eyes. Ten percent of diabetic patients will have vision loss related to macular edema. Optical Coherence Tomography can show areas of retinal thickening due to fluid accumulation from macular edema.
As the disease progresses, severe non proliferative diabetic retinopathy enters to the stage of an advanced or proliferative (PDR) stage. It is here where the blood vessels pro lifer-ate/grow. The lack of oxygen in the retina causes fragile, new, blood vessels to grow along the retina and in the clear, gel-like vitreous humour that fills the inside of the eye. The bleed (vitreous hemorrhage) and burst of the abnormal new blood vessels (neovascularisation) form at the back of the eye; can blur the vision, because these new blood vessels are fragile. Without the timely treatment, these new blood vessels can bleed which cloud vision and destroy the retina.
In some extreme cases, a person may only be able to tell light from dark in that eye. Tractional retinal detachment can also occur because of fibro vascular proliferation. The new blood vessels have the possibility to grow into the angle of the anterior chamber of the eye and cause neovascular glaucoma. Non proliferative diabetic retinopathy shows up as cotton wool spots, or microvascular abnormalities or as superficial retinal hemorrhages. Even so, the advanced proliferative diabetic retinopathy (PDR) can remain a symptomatic for a very long time, and so should be monitored closely with regular checkups.
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