Blindness

REDIRECT Visual impairment

A cataract is a cloudy area in the lens of the eye that impairs vision. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or double vision, halos around light, trouble with bright lights, and difficulty seeing at night. This may result in difficulty driving, reading and recognizing faces. Poor vision caused by cataracts may also result in an increased risk of falling and depression. In 2020 Cataracts caused 39.6% of all cases of blindness and 28.3% of visual impairment worldwide. Cataracts remain the single most common cause of global bl

right|thumb|250px|The Creation of Light by Gustave Doré

Glaucoma is a group of eye diseases that can lead to damage of the optic nerve, which transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of sight" because the loss of vision usually occurs slowly over a long period of time. A major risk factor for glaucoma is increased pressure within the eye, known as intraocular pressure (IOP). It is associated with old age, a family history of glaucoma, and certain medical conditions or the use of some medications. The word glaucoma comes from the Ancient Greek word

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.

decreased ability to see

human disease

assistance dog trained to lead blind and visually impaired people around obstacles

retinal degeneration characterized by the gradual deterioration of the photoreceptors or the retinal pigment epithelium of the retina leading to progressive sight loss

disease of the eye affecting prematurely born babies generally having received intensive neonatal care, in which oxygen therapy is used on them due to the premature development of their lungs

parable from the ancient Indian subcontinent, in which several blind men feel and try to conceptualize an elephant

lack of vitamin A in blood and tissues

Photokeratitis or ultraviolet keratitis is a painful eye condition caused by exposure of insufficiently protected eyes to the ultraviolet (UV) rays from either natural (e.g. intense direct or reflected sunlight) or artificial (e.g. the electric arc during welding) sources. Photokeratitis is akin to a sunburn of the cornea and conjunctiva.

medical condition

Hemianopsia, or hemianopia, is a loss of vision or blindness (anopsia) in half the visual field, usually on one side of the vertical midline. The most common causes of this damage are stroke, brain tumor, and trauma.

225px|thumb|right|Astronauts Richard H. Truly and [[Guion Bluford sleeping on board the Challenger. Bluford, in the foreground (upside-down) wears a sleep mask. Astronauts may find it difficult to sleep in space, especially if they are light sensitive.]] 225px|thumb|right|Sleep mask

philosophical thought experiment: “if a man born blind, who can feel the differences between shapes, is given the ability to see, could he distinguish those objects by sight?”

Helper who aids a blind person

Human disease

macular degeneration that can cause progressive vision loss, it is characterized by the disruption of cells in a small area near the center of the retina, the macula

type of physical punishment which results in complete or nearly complete loss of vision

electronic retinal implant manufactured by Second Sight Medical Products

form of visual impairment caused by a brain problem

human disease

human ability to detect surroundings using sounds

Buphthalmos (plural: buphthalmoses) is enlargement of the eyeball and is most commonly seen in infants and young children. It is sometimes referred to as buphthalmia (plural buphthalmias). It usually appears in the newborn period or the first 3 months of life. and in most cases indicates the presence of congenital (infantile) glaucoma, which is a disorder in which elevated pressures within the eye lead to structural eye damage and vision loss.

disorder of lens

metaphor

Danish mobile application

genetic disorder that primarily affects the eye and almost always leads to blindness

equine service animal assisting blind persons

visual prosthesis

medical condition

thumb|Large print books Large-print (also large-type or large-font) refers to the formatting of a book or other text document in which the font size is considerably larger than usual to accommodate people who have low vision. Frequently the medium is also increased in size to accommodate the larger text. Special-needs libraries and many public libraries will stock large-print versions of books, along with versions written in Braille.

human disease

typeface designed for visually impaired users

retinal vascular disease characterized by the prevention of blood vessel formation at the edges of the retina and the hemorrhage of the blood vessels in the retina

type of visual impairment

disorder of lens

thumb|Fundoscopy demonstrating age-related macular degeneration. A maculopathy is any pathological condition of the macula, an area at the centre of the retina that is associated with highly sensitive, accurate vision.

Stereoblindness (also spelled stereo blindness) is the inability to perceive in three-dimensional (3D) depth using stereopsis, or stereo vision, by combining and comparing images from the two eyes.