Color Perception Tests: Type of vision test used to determine COLOR VISION DEFECTS.Color Perception: Mental processing of chromatic signals (COLOR VISION) from the eye by the VISUAL CORTEX where they are converted into symbolic representations. Color perception involves numerous neurons, and is influenced not only by the distribution of wavelengths from the viewed object, but also by its background color and brightness contrast at its boundary.Color: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Speech Discrimination Tests: Tests of the ability to hear and understand speech as determined by scoring the number of words in a word list repeated correctly.Color Vision: Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).Speech Perception: The process whereby an utterance is decoded into a representation in terms of linguistic units (sequences of phonetic segments which combine to form lexical and grammatical morphemes).Cochlear Implants: Electronic hearing devices typically used for patients with normal outer and middle ear function, but defective inner ear function. In the COCHLEA, the hair cells (HAIR CELLS, VESTIBULAR) may be absent or damaged but there are residual nerve fibers. The device electrically stimulates the COCHLEAR NERVE to create sound sensation.Lighting: The illumination of an environment and the arrangement of lights to achieve an effect or optimal visibility. Its application is in domestic or in public settings and in medical and non-medical environments.Color Vision Defects: Defects of color vision are mainly hereditary traits but can be secondary to acquired or developmental abnormalities in the CONES (RETINA). Severity of hereditary defects of color vision depends on the degree of mutation of the ROD OPSINS genes (on X CHROMOSOME and CHROMOSOME 3) that code the photopigments for red, green and blue.Rod-Cone Interaction: Reciprocal action of two vertebrate photoreceptor cells (RODS AND CONES). Rod-cone interaction occurs during MESOPIC VISION in which both rods and cones are active in light transduction to the VISUAL CORTEX. Such interaction can influence visual sensitivity and luminous efficiency.Perception: The process by which the nature and meaning of sensory stimuli are recognized and interpreted.Contrast Sensitivity: The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Psychophysics: The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship.Retinal Cone Photoreceptor Cells: Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.Form Perception: The sensory discrimination of a pattern shape or outline.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.Discrimination (Psychology): Differential response to different stimuli.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Visual Cortex: Area of the OCCIPITAL LOBE concerned with the processing of visual information relayed via VISUAL PATHWAYS.Visual Fields: The total area or space visible in a person's peripheral vision with the eye looking straightforward.Ultrasonography, Doppler, Color: Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Hair Color: Color of hair or fur.Motion Perception: The real or apparent movement of objects through the visual field.Social Perception: The perceiving of attributes, characteristics, and behaviors of one's associates or social groups.Depth Perception: Perception of three-dimensionality.Eye Color: Color of the iris.Ophthalmology: A surgical specialty concerned with the structure and function of the eye and the medical and surgical treatment of its defects and diseases.Durable Medical Equipment: Devices which are very resistant to wear and may be used over a long period of time. They include items such as wheelchairs, hospital beds, artificial limbs, etc.Equipment and Supplies: Expendable and nonexpendable equipment, supplies, apparatus, and instruments that are used in diagnostic, surgical, therapeutic, scientific, and experimental procedures.Eye Diseases: Diseases affecting the eye.Equipment and Supplies, Hospital: Any materials used in providing care specifically in the hospital.Ophthalmologic Surgical Procedures: Surgery performed on the eye or any of its parts.Competitive Bidding: Pricing statements presented by more than one party for the purpose of securing a contract.Purchasing, Hospital: Hospital department responsible for the purchasing of supplies and equipment.Medicare Assignment: Concept referring to the standardized fees for services rendered by health care providers, e.g., laboratories and physicians, and reimbursement for those services under Medicare Part B. It includes acceptance by the physician.Orthotic Devices: Apparatus used to support, align, prevent, or correct deformities or to improve the function of movable parts of the body.Optic Neuritis: Inflammation of the optic nerve. Commonly associated conditions include autoimmune disorders such as MULTIPLE SCLEROSIS, infections, and granulomatous diseases. Clinical features include retro-orbital pain that is aggravated by eye movement, loss of color vision, and contrast sensitivity that may progress to severe visual loss, an afferent pupillary defect (Marcus-Gunn pupil), and in some instances optic disc hyperemia and swelling. Inflammation may occur in the portion of the nerve within the globe (neuropapillitis or anterior optic neuritis) or the portion behind the globe (retrobulbar neuritis or posterior optic neuritis).Vision Disorders: Visual impairments limiting one or more of the basic functions of the eye: visual acuity, dark adaptation, color vision, or peripheral vision. These may result from EYE DISEASES; OPTIC NERVE DISEASES; VISUAL PATHWAY diseases; OCCIPITAL LOBE diseases; OCULAR MOTILITY DISORDERS; and other conditions (From Newell, Ophthalmology: Principles and Concepts, 7th ed, p132).Phenytoin: An anticonvulsant that is used to treat a wide variety of seizures. It is also an anti-arrhythmic and a muscle relaxant. The mechanism of therapeutic action is not clear, although several cellular actions have been described including effects on ion channels, active transport, and general membrane stabilization. The mechanism of its muscle relaxant effect appears to involve a reduction in the sensitivity of muscle spindles to stretch. Phenytoin has been proposed for several other therapeutic uses, but its use has been limited by its many adverse effects and interactions with other drugs.Miotics: Agents causing contraction of the pupil of the eye. Some sources use the term miotics only for the parasympathomimetics but any drug used to induce miosis is included here.Epilepsy: A disorder characterized by recurrent episodes of paroxysmal brain dysfunction due to a sudden, disorderly, and excessive neuronal discharge. Epilepsy classification systems are generally based upon: (1) clinical features of the seizure episodes (e.g., motor seizure), (2) etiology (e.g., post-traumatic), (3) anatomic site of seizure origin (e.g., frontal lobe seizure), (4) tendency to spread to other structures in the brain, and (5) temporal patterns (e.g., nocturnal epilepsy). (From Adams et al., Principles of Neurology, 6th ed, p313)Optic Nerve: The 2nd cranial nerve which conveys visual information from the RETINA to the brain. The nerve carries the axons of the RETINAL GANGLION CELLS which sort at the OPTIC CHIASM and continue via the OPTIC TRACTS to the brain. The largest projection is to the lateral geniculate nuclei; other targets include the SUPERIOR COLLICULI and the SUPRACHIASMATIC NUCLEI. Though known as the second cranial nerve, it is considered part of the CENTRAL NERVOUS SYSTEM.Middle East: The region of southwest Asia and northeastern Africa usually considered as extending from Libya on the west to Afghanistan on the east. (From Webster's New Geographical Dictionary, 1988)YemenAnthropology: The science devoted to the comparative study of man.LebanonChromosomes, Human, Y: The human male sex chromosome, being the differential sex chromosome carried by half the male gametes and none of the female gametes in humans.Blogging: Using an INTERNET based personal journal which may consist of reflections, comments, and often hyperlinks.Anthropology, Physical: The comparative science dealing with the physical characteristics of humans as related to their origin, evolution, and development in the total environment.