Detection of Glaucoma Using Cup to Disc Ratio From Spectral Domain Optical Coherence Tomography Images

Abstract

Glaucoma is an asymptomatic neurological disease. It causes damage to optic nerve due to increased fluid pressure within eyes. In the proposed system, cup-to-disc-ratio has been computed considering internal layers of the retina using spectral-domain optical coherence tomography images. In the cupdiameter-calculation process, cup contour has been extracted from inner-limiting-membrane (ILM) layer. The paper introduces a new method to improve the precision of the ILM-layer extraction. It also employs a novel technique to refine contour of an ILM layer. The novel method has outperformed interpolation and Bezier curve fitting in term of outliers' removal and surface refinement. In the disc-diameter-calculation process, the retinal-pigment-epithelium (RPE) layer end points have been used to define disc margin. Prior to RPE-layer extraction, ILM-Layer removal has been done by an innovative strategy to locate and remove ILM-layer. Finally, precise RPE-layer extraction has been done based on the novel thickness-value (TV) estimation method. Furthermore, a new criterion for cup edges determination, based on the mean value of RPE-layer end points, is proposed. The proposed system has shown a clear precedence over its contemporary systems in terms of accuracy and handling of acute cases. Satisfactory results have been obtained when compared with the clinical results.