Visual disturbances and blindness

REDIRECT Visual impairment

inability or decreased ability to see colour, or perceive colour differences, under normal lighting conditions

Nyctalopia (; ), also called night blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by injury or malnutrition (for example, vitamin A deficiency). It can be described as insufficient adaptation to darkness.

Prosopagnosia, also known as face blindness, is a cognitive disorder of face perception in which the ability to recognize familiar faces, including one's own face (self-recognition), is impaired, while other aspects of visual processing (e.g., object discrimination) and intellectual functioning (e.g., decision-making) remain intact. The term originally referred to a condition following acute brain damage (acquired prosopagnosia), but a congenital or developmental form of the disorder also exists, with a prevalence of 2–2.5%.

retinal degeneration characterized by gradual deterioration of light-sensing cells in the tissues at the back of the eye

Diplopia is the simultaneous perception of two images of a single object that may be displaced in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often voluntary. However, when occurring involuntarily, it results from impaired function of the extraocular muscles, where both eyes are still functional, but they cannot turn to target the desired object. Problems with these muscles may be due to mechanical problems, disorders of the neuromuscular junction, disorders of the cranial nerves (III, IV, and VI) that innervate the muscles,

Photophobia is a medical symptom of abnormal intolerance to visual perception of light. As a medical symptom, photophobia is not a morbid fear or phobia, but an experience of discomfort or pain to the eyes due to light exposure or by presence of actual physical sensitivity of the eyes, though the term is sometimes additionally applied to abnormal or irrational fear of light, such as heliophobia. The term photophobia comes .

visual impairment

Achromatopsia, also known as rod monochromacy, is a medical syndrome that exhibits symptoms relating to five conditions, most notably monochromacy. Historically, the name referred to monochromacy in general, but now typically refers only to an autosomal recessive congenital color vision condition. The term is also used to describe cerebral achromatopsia, though monochromacy is usually the only common symptom. The conditions include: monochromatic color blindness, poor visual acuity, and day-blindness. The syndrome is also present in an incomplete form that exhibits milder symptoms, including r

Human disease

Akinetopsia (from Greek akinesia 'absence of movement' and opsis 'seeing'), also known as cerebral akinetopsia or motion blindness, is an extremely rare neuropsychological disorder, having only been documented in a handful of medical cases, in which a patient cannot perceive motion in their visual field, despite being able to see stationary objects without issue. The syndrome is the result of damage to visual area V5, whose cells are specialized to detect directional visual motion. There are varying degrees of akinetopsia: from seeing motion as frames of a cinema reel to an inability to discri

A scotoma is an area of partial alteration in the field of vision consisting of a partially diminished or entirely degenerated visual acuity that is surrounded by a field of normal – or relatively well-preserved – vision.

retinal disease that is characterized by nystagmus, sluggish or no pupillary responses, and severe vision loss or blindness

Macropsia is a neurological condition affecting human visual perception, in which objects within an affected section of the visual field appear larger than normal, causing the person to feel smaller than they actually are. Macropsia, along with its opposite condition, micropsia, can be categorized under dysmetropsia. Macropsia is related to other conditions dealing with visual perception, such as aniseikonia and Alice in Wonderland Syndrome (AIWS, also known as Todd's syndrome). Macropsia has a wide range of causes, from prescription and illicit drugs, to migraines and (rarely) complex partial

impairment in recognition of visually presented objects

Migraine causing aura in vision

visual aura

disease of the eye in response to changes in the vitreous humor or more rarely, diabetes

Monochromacy (from Greek mono, meaning "one" and chromo, meaning "color") is the ability of organisms to perceive only light intensity without respect to spectral composition. Organisms with monochromacy lack color vision and can only see in shades of grey ranging from black to white. Organisms with monochromacy are called monochromats. Many mammals, such as cetaceans, the owl monkey and the Australian sea lion are monochromats. In humans, monochromacy is one among several other symptoms of severe inherited or acquired diseases, including achromatopsia or blue cone monochromacy, together affec

Micropsia is a condition affecting human visual perception in which objects are perceived to be smaller than they actually are. Micropsia can be caused by optical factors (such as wearing glasses), by distortion of images in the eye (such as optically, via swelling of the cornea or from changes in the shape of the retina such as from retinal edema, macular degeneration, or central serous retinopathy), by changes in the brain (such as from traumatic brain injury, epilepsy, migraines, or drugs), and from psychological factors. Dissociative phenomena are linked with micropsia, which may be the re

medical rehabilitation measures to improve vision

Palinopsia () is the persistent recurrence of a visual image after the stimulus has been removed. Palinopsia is not a diagnosis; it is a diverse group of pathological visual symptoms with a wide variety of causes. Visual perseveration is synonymous with palinopsia.

right|thumb|The Amsler grid showing the visual perception of the left eye of a person experiencing metamorphopsia (straight lines appear bent or curved)

Hemeralopia or day blindness is the inability to see clearly in bright light and is the exact opposite of nyctalopia (night blindness), the inability to see clearly in low light. It is also called heliophobia. It can be described as insufficient adaptation to bright light.

An anopsia, or anopia, () is a defect in the visual field. If the defect is only partial, then the portion of the field with the defect can be used to isolate the underlying cause. It is particularly used to describe the lack of sight in one eye.

human disease

550px|thumb|right| The Harbisson's Sonochromatic Music Scale An eyeborg or eye-borg is a body modification apparatus which fits on the wearer's head, and is designed to allow people to perceive color through sound waves. It works with a head-mounted antenna that senses the colors directly in front of a person, and converts them in real-time into sound waves through bone conduction.

Quadrantanopia, quadrantanopsia, refers to an anopia (loss of vision) affecting a quarter of the visual field.

medical condition

plastic surgery of the sclera, procedure used frequently to prevent blindness and poor vision

thumb|Example ColorADD symbols for seven colors ColorADD is a sign code for aiding color blind people to recognize colors, developed by Portuguese graphic designer and professor at the University of Minho, Miguel Neiva. It consists of geometric shapes representing colors and color combinations. The app won the accessibility category of the 2013 Vodafone Foundation Mobile For Good Europe Awards.

human disease

Human disease

Pelopsia, a facet of Alice in Wonderland Syndrome (AIWS), is a vision perception disorder in which objects appear nearer than they actually are. Objects may also appear to be coming closer when they are not. Pelopsia and other conditions that fall under AIWS are usually temporary, which may justify the lack of research done on this subject. Pelopsia can be caused by psychoneurotic phenomena, changes in atmospheric clarity, or sometimes by wearing a corrective lens. AIWS is most common in children, with them accounting for 2/3 of documented cases. The most common way to treat this disorder is b

Prosopometamorphopsia (PMO), also known as demon face syndrome, is a neurological disorder characterized by altered perceptions of faces. In the perception of a person with the disorder, facial features are distorted in a variety of ways including drooping, swelling, discoloration, and shifts of position.