Explore chapters and articles related to this topic
Introduction
Published in Arwa Ahmed Gasm Elseid, Alnazier Osman Mohammed Hamza, Computer-Aided Glaucoma Diagnosis System, 2020
Arwa Ahmed Gasm Elseid, Alnazier Osman Mohammed Hamza
In the second method, a large proportion of glaucoma patients have a normal level of IOP. Thus, IOP measurement is neither specific nor sensitive enough to be used for the effective screening for early glaucoma. The assessment of optic nerve damage is the best of the other two methods (Zhang et al., 2012). The main methods for optic nerve assessment by trained specialists are 3-D imaging techniques such as Heidelberg Retinal Tomography (HRT) and Ocular Computing Tomography (OCT). However, optic nerve assessment by specialists is subjective and the availability of HRT and OCT equipment is limited due to its expense. In summary, there is still no systematic and economic way of detecting glaucoma. There is a need for an automatic and economically viable system for the detection of glaucoma in an accurate way, possibly by using the digital color fundus image in Figure 1.1, which is a more cost-effective imaging modality to assess optic nerve damage compared to HRT and OCT, and has been widely used in recent years to diagnose various ocular diseases including glaucoma. In this research, a system for diagnosing glaucoma from non-glaucoma cases via fundus images analysis has been proposed.
Digital Image Processing and Visual Perception
Published in Scott E. Umbaugh, Digital Image Processing and Analysis, 2017
The HVS has two primary components—the eye and the brain, which are connected by the optic nerve (see Figure 7.2-1). The structure that we know the most about is the image-receiving organ—the human eye. The brain can be thought of as being an information processing unit, analogous to the computer in our computer imaging system. These two are connected by the optic nerve, which is a bundle of nerves that contains the pathways for the visual information to travel from the receiving sensor, the eye, to the processor, the brain. The HVS operates as follows: (1) light energy is focused by the lens of the eye onto the sensors on the retina at the back of the eye; (2) these sensors respond to this light energy by an electrochemical reaction that sends an electrical signal down the optic nerve to the brain; and (3) the brain uses these nerve signals to create neurological patterns that are perceived as images.
Computer-Aided Diagnosis with Retinal Fundus Images
Published in de Azevedo-Marques Paulo Mazzoncini, Mencattini Arianna, Salmeri Marcello, Rangayyan Rangaraj M., Medical Image Analysis and Informatics: Computer-Aided Diagnosis and Therapy, 2018
Glaucoma is the second leading cause of blindness in the world. Once the optic nerve is damaged and the visual field deteriorates, it cannot recover. Therefore, early detection of glaucoma is important for halting disease progression and preventing total blindness. However, due to the lack of symptoms and the slow progression in its early stages, most patients do not consult a doctor until glaucoma reaches advanced stages. Retinal imaging is an easy and effective diagnostic exam. Retinal image findings that indicate glaucoma include large cupping, rim loss, rim notching, peripapillary atrophy (PPA), and nerve fiber layer defects (NFLDs). Methods for detection of large cupping and NFLDs are described in the following sections.
The therapeutic effect of nano-zinc on the optic nerve of offspring rats and their mothers treated with lipopolysaccharides
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Eman Mohammed Emara, Hassan Ih El-Sayyad, Amr M Mowafy, Heba a El-Ghaweet
The optic nerve (cranial nerve II) is a central nervous system (CNS) tract that passes through the optic canal to leave the orbit. It is made up of the retinal ganglion cells (RGCs) axons. It allows vision by transmitting neural impulses from the retina to the brain. It is divided into four sections: the intraocular nerve head, the intraorbital, the intracanalicular and the intracranial [6]. The types of glial cells in the optic nerve are oligodendrocytes, astrocytes and microglia. Oligodendrocytes are responsible for producing the myelin sheaths that protect the CNS axons and contact nodes of Ranvier as well as they are the locations where action potentials are propagated and axonal integrity. Astrocytes are responsible for numerous physiological and pathological activities such as potassium homeostasis and metabolism as well as reactive astrogliosis in response to CNS trauma. Microglia are immune cells in CNS and have a significant impact on inflammation and infections [7].
A Functional BCI Model by the P2731 working group: Physiology
Published in Brain-Computer Interfaces, 2021
Ali Hossaini, Davide Valeriani, Chang S. Nam, Raffaele Ferrante, Mufti Mahmud
Optic nerves transmit information from retinas to the occipital lobe. After undergoing processing in the occipital lobe, visual signals are then split into two physiologically distinct streams – the dorsal (top) visual stream which runs from the occipital lobe through the parietal lobe, and the ventral (bottom) visual stream which runs from the occipital lobe to the temporal lobe and several subcortical structures [28]. Motor responses, sensory memory and imagination, and conscious awareness enlist even more parts of the brain. While much of the brain’s processing occurs in multiple locations or linear streams, its organization does contain identifiable nodes that can interface effectively with BCI. The following example clarifies this statement.
Mapping the importance of specific physical elements in urban space for blind and visually impaired people
Published in Journal of Urban Design, 2023
Annette Bredmose, Sidse Grangaard, Victoria Linn Lygum, Anders Rhiger Hansen
Sight function can be divided in two parts: The physical and sensory aspect where the eye perceives light and sends signals via the optic nerve to the brain.The perceptual sight function where the brain forms pictures from the sensory perception.