A vision disorder is an impairment of the sense of

vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...

. Vision disorder is not the same as an

eye disease This is a partial list of human eye diseases and disorders. The World Health Organization publishes a classification of known diseases and injuries, the International Statistical Classification of Diseases and Related Health Problems, or ICD-10. ...

. Although many vision disorders do have their immediate cause in the eye, there are many other causes that may occur at other locations in the optic pathway.

Causes

There are many eye conditions that can lead to vision disorder. Some of which are as follows: *

Age-Related Macular Degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, som ...

(ARMD): ARMD is a retinal degeneration disease specifically associated with

macula The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal av ...

blood vessels, which can result in central vision impairment. It is strongly linked to advancing age, as well as European ancestry. * Bulging eyes: where the eye (one or both) protrudes or distends out of its orbit. Left untreated, bulging eyes may lead to eye dryness, pain and vision loss * Cytomegalovirus (CMV) Retinitis: This is an inflammation of the

retina The retina (from la, rete "net") is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which the ...

caused by infection, which can result in blindness. It occurs in people experiencing suppressed

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

s, most commonly by Acquired Immunodeficiency Syndrome (AIDS). *

Diabetic Macular Edema Diabetic retinopathy (also known as diabetic eye disease), is a medical condition in which damage occurs to the retina due to diabetes mellitus. It is a leading cause of blindness in developed countries. Diabetic retinopathy affects up to 80 perc ...

(DME): is an eye disease specifically related to

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

, occurring due to fluid build-up in the

as a result of sustained high

blood glucose Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the b ...

levels. It can result in blurred vision and vision loss. * Eye floaters and spots: where visible cloud-like images appear to "float" in an individual's field of vision. Floaters and spots are most commonly related to ageing. They are generally harmless and do not cause blindness * Eye flashing: characterised by bursts or streaks of light that appear in an individual's field of vision. As eye flashing may indicate impending

retinal detachment Retinal detachment is a disorder of the eye in which the retina peels away from its underlying layer of support tissue. Initial detachment may be localized, but without rapid treatment the entire retina may detach, leading to vision loss and blin ...

, medical attention is required. * Eyelid twitching: where the eyelid muscles contract in an irregular or abnormal pattern. Such movements can cause irritation and fatigue to the eyes. *

Glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for aqueous humor, fluid withi ...

: occurs when the

optic nerve In neuroanatomy, the optic nerve, also known as the second cranial nerve, cranial nerve II, or simply CN II, is a paired cranial nerve that transmits visual information from the retina to the brain. In humans, the optic nerve is derived fro ...

is damaged and can result in irreversible vision loss, with the potential to pass undetected until this damage occurs. It is caused when

aqueous humour The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posteri ...

fails to adequately drain from the eye, resulting in pressure build-up. *

Keratoconus Keratoconus (KC) is a disorder of the eye that results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, irregular astigmatism, and light sensitivity leading to poor quality-of-life. ...

: vision problems can be caused when the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical ...

thins and distorts into a conical shape. While the cause is unknown, Keratoconus is believed to be

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

, and can be exacerbated by allergies and eye rubbing. *

Strabismus Strabismus is a vision disorder in which the eyes do not properly align with each other when looking at an object. The eye that is focused on an object can alternate. The condition may be present occasionally or constantly. If present during a ...

: where the muscular or neural control of gaze direction fails to align the eyes to a shared locus of visual attention, sometimes leading to

double vision Diplopia is the simultaneous perception of two images of a single object that may be displaced horizontally or vertically in relation to each other. Also called double vision, it is a loss of visual focus under regular conditions, and is often v ...

Uveitis Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and in ...

: where the uveal (middle) layer of the eye is inflamed. Uveitis requires medical intervention as it can lead to

blurry vision Blurred vision is an ocular symptom where vision becomes less precise and there is added difficulty to resolve fine details. Temporary blurred vision may involve dry eyes, eye infections, alcohol poisoning, hypoglycemia, or low blood pressure. ...

, eye pain, eye floaters, eye redness and vision loss

Epidemiology

It was estimated by the

WHO Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book '' Horton He ...

in 2004 that 314 million people worldwide are vision impaired (from all causes), of whom 45 million are blind. Vision disorders are not often targeted by public health initiatives, as mortality causes take priority. However, they can have significant impact on a person's quality of life, affecting performance at school and the workplace if not corrected.

References

External links

{{Authority control Visual disturbances and blindness

Causes

Epidemiology

See also

References

External links