Microaneurysms and Contrast limited adaptive histogram equalization. The

Microaneurysms are the
early visible warning of estimating diabetic retinopathy from digital color
fundus images. Though, they are the earliest signs of detection, it is a very
critical step in screening them practically. The image processing techniques are
used in detection and categorization of Microaneurysms. Initially, the
preprocessing is done by Green channel extraction; Gaussian filtering and
Contrast limited adaptive histogram equalization. The segmentation is done with
wavelet transformation technique. Thus a novel transformation is in use to
mainly obtain the better performance than other methods that are previously
used. Features are extracted from the transformed image such as the statistical
features, texture features, etc. The databases that are generally used here are
DRIVE, DIARETDB1, MESSIDOR, E-OPHTHA . And the detected Microaneurysms are
classified into three major categories namely as mild, moderate and severe
based on the numerical values in the retinal images. The Adaptive Neuro Fuzzy
System is used as the main classifier to classify the severity of the diseases
and the results are analyzed. The algorithm resulted in better performance
giving out good accuracy in each of the four databases used.The
human eye is a complex organ and is of spheroid structure that lies in a bony
cavity at the front of the head. The sclera, the choroids and the retina are
the three covering layers in the eyeball. The outermost layer of eye tissue is
called sclera. The second layer of the tissue underneath the sclera is the
choroid which consists of dense pigments and blood vessels that nourish the
tissues. The size of the pupil is regulated by iris. The inner surface of the
eye known as the retina contains rods and cones that serve the task of
detecting the intensity and the frequency of the incoming light. The light
energy is converted to electric signals by the retina and sent to the brain
through optic nerves. Fig. 1 illustrates the cross-section of a human eye and
points out its major componentsStructure
of a Human Eye Retina consists of 120 million rods and 6 million cones which
send nerve impulses to the brain and travel through a network of nerve cells.
There are one-million neural pathways from the rods and cones to the brain. Structure
of Retina Macula is present at the center of the retina of the human eye and is
a small and light sensitive layer of tissue at the back of the retina. It is
responsible for sharp, clear and detailed central vision. The fovea is found at
the center of the macula and consists of light sensitive cells. Optic Disc (OD)
is the brightest region on the retina and is usually round at the back of the
inside of the eye.

Diabetic
Retinopathy (DR) is the most common cause of new cases of blindness among
adults aged between 20 and 74 years. The blood vessels of the retina get
damaged and lead to leakage of blood and fluid into the retinal surface. There
is vision impairment when the nerve cells are damaged. Initially there are no symptoms
for DR and a vision problem would occur only during later stages. If the blood
sugar level is not controlled, it would weaken and damage the blood vessels in
the retina causing abnormal auto regulation. Hence the vessels do not constrict
adequately due to sudden increase of blood flow. There is an increase in shear
stress on the vessel walls which damage the vessels and leads to vascular
complications. It is irreversible and would eventually direct to blindness if
ignored. Therefore, early diagnosis is important to stop the disease from
worsening. WHO lists DR as one of its priority eye diseases and includes it
into its action plan for the prevention of inevitable blindness and visual
impairment16.

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The retinal disease starts from mild
Non-Proliferative Diabetic Retinopathy (NPDR) which is characterized by
abnormal lesions and changes in blood vessels to moderate and severe NPDR which
are characterized by vessel closure. It progresses from NPDR to Proliferative
Diabetic Retinopathy (PDR) and is characterized by the growth of new blood
vessels. Due to the presence of microvascular complications, loss of vision and
blindness can occur in diabetic patients.