Coma: A profound state of unconsciousness associated with depressed cerebral activity from which the individual cannot be aroused. Coma generally occurs when there is dysfunction or injury involving both cerebral hemispheres or the brain stem RETICULAR FORMATION.Glasgow Coma Scale: A scale that assesses the response to stimuli in patients with craniocerebral injuries. The parameters are eye opening, motor response, and verbal response.Diabetic Coma: A state of unconsciousness as a complication of diabetes mellitus. It occurs in cases of extreme HYPERGLYCEMIA or extreme HYPOGLYCEMIA as a complication of INSULIN therapy.Insulin Coma: Severe HYPOGLYCEMIA induced by a large dose of exogenous INSULIN resulting in a COMA or profound state of unconsciousness from which the individual cannot be aroused.Coma, Post-Head Injury: Prolonged unconsciousness from which the individual cannot be aroused, associated with traumatic injuries to the BRAIN. This may be defined as unconsciousness persisting for 6 hours or longer. Coma results from injury to both cerebral hemispheres or the RETICULAR FORMATION of the BRAIN STEM. Contributing mechanisms include DIFFUSE AXONAL INJURY and BRAIN EDEMA. (From J Neurotrauma 1997 Oct;14(10):699-713)Myxedema: A condition characterized by a dry, waxy type of swelling (EDEMA) with abnormal deposits of MUCOPOLYSACCHARIDES in the SKIN and other tissues. It is caused by a deficiency of THYROID HORMONES. The skin becomes puffy around the eyes and on the cheeks. The face is dull and expressionless with thickened nose and lips.Hyperglycemic Hyperosmolar Nonketotic Coma: A serious complication of TYPE 2 DIABETES MELLITUS. It is characterized by extreme HYPERGLYCEMIA; DEHYDRATION; serum hyperosmolarity; and depressed consciousness leading to COMA in the absence of KETOSIS and ACIDOSIS.Brain Injuries: Acute and chronic (see also BRAIN INJURIES, CHRONIC) injuries to the brain, including the cerebral hemispheres, CEREBELLUM, and BRAIN STEM. Clinical manifestations depend on the nature of injury. Diffuse trauma to the brain is frequently associated with DIFFUSE AXONAL INJURY or COMA, POST-TRAUMATIC. Localized injuries may be associated with NEUROBEHAVIORAL MANIFESTATIONS; HEMIPARESIS, or other focal neurologic deficits.Craniocerebral Trauma: Traumatic injuries involving the cranium and intracranial structures (i.e., BRAIN; CRANIAL NERVES; MENINGES; and other structures). Injuries may be classified by whether or not the skull is penetrated (i.e., penetrating vs. nonpenetrating) or whether there is an associated hemorrhage.Hepatic Encephalopathy: A syndrome characterized by central nervous system dysfunction in association with LIVER FAILURE, including portal-systemic shunts. Clinical features include lethargy and CONFUSION (frequently progressing to COMA); ASTERIXIS; NYSTAGMUS, PATHOLOGIC; brisk oculovestibular reflexes; decorticate and decerebrate posturing; MUSCLE SPASTICITY; and bilateral extensor plantar reflexes (see REFLEX, BABINSKI). ELECTROENCEPHALOGRAPHY may demonstrate triphasic waves. (From Adams et al., Principles of Neurology, 6th ed, pp1117-20; Plum & Posner, Diagnosis of Stupor and Coma, 3rd ed, p222-5)Malaria, Cerebral: A condition characterized by somnolence or coma in the presence of an acute infection with PLASMODIUM FALCIPARUM (and rarely other Plasmodium species). Initial clinical manifestations include HEADACHES; SEIZURES; and alterations of mentation followed by a rapid progression to COMA. Pathologic features include cerebral capillaries filled with parasitized erythrocytes and multiple small foci of cortical and subcortical necrosis. (From Adams et al., Principles of Neurology, 6th ed, p136)Persistent Vegetative State: Vegetative state refers to the neurocognitive status of individuals with severe brain damage, in whom physiologic functions (sleep-wake cycles, autonomic control, and breathing) persist, but awareness (including all cognitive function and emotion) is abolished.Corneal Wavefront Aberration: Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.Aberrometry: The use of an aberrometer to measure eye tissue imperfections or abnormalities based on the way light passes through the eye which affects the ability of the eye to focus properly.Trauma Severity Indices: Systems for assessing, classifying, and coding injuries. These systems are used in medical records, surveillance systems, and state and national registries to aid in the collection and reporting of trauma.Glasgow Outcome Scale: A scale that assesses the outcome of serious craniocerebral injuries, based on the level of regained social functioning.Astigmatism: Unequal curvature of the refractive surfaces of the eye. Thus a point source of light cannot be brought to a point focus on the retina but is spread over a more or less diffuse area. This results from the radius of curvature in one plane being longer or shorter than the radius at right angles to it. (Dorland, 27th ed)Corneal Topography: The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.