Blindness and visual impairment

Context

Worldwide, about 217 million people have low vision, and about 36 million are blind:
  • About 90% of the world's visually impaired live in low-income settings.
  • 81% of people who are blind or have moderate or severe vision impairment are aged 50 years and above.
  • 80% of visual impairment can be prevented or cured.
  • China, India, and Africa account for approximately 8M, 8M, and 6M cases of blindness, respectively.
(WHO, Fact Sheet #282, 2017)

Causes

Age-Related Macular Degeneration (ARMD)

Unoperated cataract remains the leading cause of blindness in low- and middle-income countries. (WHO, 2017)

Cataract

Unoperated cataract remains the leading cause of blindness in low- and middle-income countries. (WHO, 2017)
Risk factors include:
  • Age: More than one-third of those over 65 have cataract.
  • Female: Females are 1.35 times more likely to have cataract.
  • Sunlight exposure: Those exposed to more than 11 hours of daily sunlight are nearly three times as likely to develop cataract as those exposed to less than 8 hours of sunlight.

Corneal blindness

Includes Xerophthalmia (nutritional blindness), Trachoma, corneal ulcer, and injuries (accidental, iatrogenic). (Dahal, 2018)

Diabetic Retinopathy


Glaucoma


Onchocerciasis (River blindness)

Caused by a roundworm infection spread by black flies.
The Farmer and Fisherman Who Lost His Sight to River Blindness

Retinitis Pigmentosa (RP)


Stargardts


Trachoma

A chronic, contagious infection that eventually causes blindness; manifests gradually. Tends to occur in clusters, infecting families or communities. WHO uses a SAFE (Surgery, Antibiotics, Face-washing, Environmental improvement) strategy against Trachoma. (Dahal, 2018)

Xerophthalmia/Vitamin A deficiency/Night Blindness

Caused by severe vitamin A deficiency, and described by pathologic dryness of the conjunctiva and cornea.

Multiple impairment

Deaf-Blind

"Deaf-blindness refers to the combination of hearing and visual loss that severely impedes communication, education, employment, and independent living. While some deaf-blind individuals are totally deaf and blind, most deaf-blind people have different levels of vision and hearing loss." (NLS)
Play-by-play soccer for a deaf-blind person
Striped canes signify deaf-blindness
Library of Congress resources



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