International Journal on Recent and Innovation Trends in Computing and Communication ISSN: 2321-8169 Volume: 5 Issue: 10 54 – 58 _______________________________________________________________________________________________ 54 IJRITCC | October 2017, Available @ http://www.ijritcc.org _______________________________________________________________________________________ Review on Optic Disc Localization Techniques G.Jasmine PG Scholar Department of computer Science and Engineering V V College of Engineering Tisaiyanvilai, India jasminenesathebam@gmail.com Dr. S. Ebenezer Juliet M.E., Ph.D., Department of Computer Science and Engineering V V College of Engineering Tisaiyanvilai juliet_sehar@yahoo.com Abstract-The optic disc (OD) is one of the important part of the eye for detecting various diseases such as Diabetic Retinopathy and Glaucoma. The localization of optic disc is extremely important for determining hard exudates and lesions. Diagnosis of the disease can prevent people from vision loss. This paper analyzes various techniques which are proposed by different authors for the exact localization of optic disc to prevent vision loss. Keywords: Localization, Optic Disc (OD), Corner Detector, Vessel Convergence, Vessel Enhancement __________________________________________________*****_________________________________________________ I. INTRODUCTION The retina is thin layer of tissue, in which the blood vessels are clearly visualized. Its purpose is to receive the light and convert it to neural signals and these signals are send to the brain for the visual recognition [16]. The brightest region in the retinal image is the optic disc. The blood vessels originate from the center of optic disc. It is classified according to its size. The slit lamp examination is done with fundocopic lens from which vertical and horizontal disc diameter are obtained. The Optic disc cup increase in size with the disc size, where large cups are obtained in healthy eyes. It is also called as optic nerve head and blind spot [3]. Optic disc is not sensitive to light because of the absence of light sensitive rods and cone in the retina, so it is called as blind spot. Optic disc is located in the vessel convergence region. The localization of optic disc is done mainly to save people from vision loss. Fig 1. Optic Disc Optic disc is mainly used for detecting various diseases such as diabetic retinopathy and glaucoma. It can also be used for the detection of other anatomical structures such as macula and retinal vessels [10]. The major health problem that has increased recently is the Diabetic retinopathy. It is an asymptomatic disease which can lead to loss of vision. About 10,000 people lose their vision due to diabetic retinopathy. Retinal Treatment is the best method for reducing the vision loss. Regular eye examinations are required for detecting and treating the diabetic retinopathy [10]. The detection of optic disc in retinal image is very important for the exact localization of optic disc. To find the abnormal structures in the image it is to be mask out from the analysis. Optic disc detection is one of the important step for diabetic retinopathy and glaucoma for screening system. The optic disc boundary and the localization of macula is used for the detection of exudates and diabetic maculopathy. In diabetic maculopathy masking the false positive OD leads to improve in performance of lesion detection. The OD position is used as a reference length for measuring the distances in retinal images. The location of OD becomes the starting point for vessel tracking. Thus the optic disc localization is performed [4]. II. Techniques For Optic Disc Localization Optic disc localization is extremely important for determining the hard exudate lesions or nonvascularization. By localizing the optic disc, blindness can be reduced. To localize Optic Disc various methods are available. In this survey some of the methods are discussed below. 2.1 Approximate nearest neighbor field based optic disc detection A feature match ANNF algorithm Proposed in [14], to find the correspondence between the optic disc images. The correspondence between the images provides patches in the query image which are close to the reference image. This method uses only one retinal image which is used to extract the reference optic disc image. The given input image is preprocessed, in which reference optic disc is considered as an algorithm and the target image is considered as feature match. Then query image is preprocessed, i.e. it is equalized and converted to grayscale. ANNF searches the nearest patches