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Medical and Mathematical Background
Published in Arwa Ahmed Gasm Elseid, Alnazier Osman Mohammed Hamza, Computer-Aided Glaucoma Diagnosis System, 2020
Arwa Ahmed Gasm Elseid, Alnazier Osman Mohammed Hamza
The optic nerve on the retina is also called the blind spot, as it is insensitive to light. Often, the fovea, optic nerve, retina, and retinal vasculature are referred to as the ocular fundus structures.
Chronic Hyperglycemia Impairs Vision, Hearing, and Sensory Function
Published in Robert Fried, Richard M. Carlton, Type 2 Diabetes, 2018
Robert Fried, Richard M. Carlton
Diabetes mellitus can cause two types of changes in the eye: Nonproliferative diabetic retinopathy occurs first. Proliferative diabetic retinopathy occurs after nonproliferative diabetic retinopathy, and it is more severe. In nonproliferative diabetic retinopathy, small blood vessels in the retina leak fluid or blood and may develop small bulges. Areas of the retina affected by leakage may swell, causing damage to parts of the field of vision. At first, the effects on vision may be minimal, but gradually vision may become impaired. Blind spots may appear, although these may not be noticed at first, and they are usually discovered only during testing.
The retina, optic nerve and vitreous humour
Published in Mary E. Shaw, Agnes Lee, Ophthalmic Nursing, 2018
The optic disc (Figure 13.2) is the area of the retina where the axons of the ganglion cells leave the eye through the lamina cribrosa to become continuous with the optic nerve. It therefore contains no nerve cells, so that vision cannot take place here. This is known as the ‘blind spot’. The central retinal artery and vein pass through the optic disc. Its blood supply is from the posterior ciliary artery, a branch of the temporal artery.
Did hypervitaminosis A have a role in Mawson’s ill-fated Antarctic exploration?
Published in Clinical Toxicology, 2022
Symptoms of acute hypervitaminosis A are related most significantly to the brain. After an acute large ingestion, a condition known as pseudotumor cerebri, now called idiopathic intracranial hypertension occurs [22,23]. It is characterized by increased pressure in the cerebral spinal fluid (CSF), exerting pressure on the brain and causing headache, papilledema, and visual disturbances [22,23]. This could occur with a single large ingestion of vitamin A with an onset of several hours. This condition presents initially with symptoms of headaches, sleepiness, and fatigue [9,14,15,22]. Although these complaints are certainly not specific to hypervitaminosis A, and may occur in many disorders, an interpretive reading into the Mawson journals shows these symptoms occurring in Mertz. As the disease progresses, increased central nervous system intracranial pressure will cause blind spots to develop in the visual field, then obtundation, and finally severe altered mental status occurs.
Ocular manifestations of endocrine disorders
Published in Clinical and Experimental Optometry, 2022
M Hossein Nowroozzadeh, Sarah Thornton, Alison Watson, Zeba A Syed, Reza Razeghinejad
Diabetic papillopathy is considered a diagnosis of exclusion in a diabetic patient with unilateral or bilateral disc oedema. Patients generally have mild vision loss and there may be visual field defects, including blind spot enlargement.22 This condition is likely related to decreased optic nerve head perfusion in the setting of diabetic vascular disease, although the mechanism has not been clearly defined. Fundoscopy may reveal prominent telangiectasias on the nerve and disc oedema in one or both eyes.23 Diabetic papillopathy has a generally benign course with visual improvement expected over weeks to months. There have been some reports of expedited recovery with the use of intravitreal triamcinolone acetate or intravitreal anti-vascular endothelial growth factor agents.24,25
Dissociative Symptoms are Highly Prevalent in Adults with Narcolepsy Type 1
Published in Behavioral Sleep Medicine, 2022
Laury Quaedackers, Hal Droogleever Fortuyn, Merel Van Gilst, Martijn Lappenschaar, Sebastiaan Overeem
More and more it is becoming clear that the spectrum of narcolepsy is much broader than the “narcoleptic pentad” (Canellas et al., 2014; Droogleever Fortuyn et al., 2012; Fortuyn et al., 2010; Zhang et al., 2018). From a clinical point of view, this might lead to difficulties not to miss symptoms, or having “blind spots”. From a research perspective, it also raises the question if these, perhaps less obvious, symptoms have interdependencies and could possibly be clustered. Longitudinal monitoring of the broad spectrum of narcolepsy symptoms may be useful to discover such relations and to increase our understanding of the course of symptoms. Modern tools may help in such studies, for example, with the Narcolepsy Monitor, a recently developed mobile app enabling long-term monitoring of the subjective severity of a wide range of narcolepsy symptoms (Quaedackers et al., 2020).