Transcript Blindness

Blindness
Ines Serrano MD
Evan Waxman MD PHD
"There is no better way to thank God for your sight than
by giving a helping hand to someone in the dark.”
Helen Keller
Every five seconds one person in the world
goes blind.
One child goes blind every minute.
http://www.who.int/mediacentre/news/releases/pr79/en/
Facts
http://www.kernersvillerotary.org/images2009/052107BlindSchool7.JPG
According to WHO:
 It is estimated that over seven million people become blind
every year.
 75% of blindness is avoidable
 80% of visual impairment is avoidable
 63% of those with low vision and 82% of blind people are
over 50 years of age
 Of the six WHO regions, South East Asia and Western
Pacific account for 73% of moderate to severe visual
impairment and 58% of blindness.
http://www.who.int/topics/blindness/en/
Key Facts
 About 285 million people are visually impaired world wide,
39.8 million of them are blind
 Most of the people with visual impairment are older, and
females are more at risk at every age, in every part of the
world.
 90% of people with visual impairments live in developing
countries
http://www.who.int/mediacentre/factsheets/fs282/en/index.html
Key Facts
 Cataract remains the leading cause of blindness globally,
except in the most developed countries.
 Cataract surgery and correction of refractive errors are
among the most cost-effective health interventions.
http://www.who.int/features/factfiles/vision/04_en.html
Key Facts
 1.4 million children under age 15 are blind.
 Correction of refractive errors could give normal vision to
more than 12 million children (ages 5-15).
 The number of people blinded by infectious diseases has
been greatly reduced. Age related impairment is increasing.
 Blinding trachoma affects 40 million people today, compared
to 360 million in 1985.
http://www.who.int/features/factfiles/blindness/blindness_facts/en/index7.html
DEFINITION
 A key issue in any discussion of blindness is its definition.
The elements of this definition that need attention are
 level of distance visual acuity,
 presenting or best-corrected visual acuity
 visual field constriction.
 In the United States, legal blindness is defined as distance
visual acuity ≤20/200.
Tasman, Duane's Ophthalmology, Lippincott Williams & Wilkins ( 2005)
Definitions (ICD-10):H54
 Low Vision: Visual acuity of less than 6/18 but equal to
better than 3/60 or corresponding visual field loss to less than
20 degrees in the better eye with the best possible correction
 Blindness: Visual acuity <3/60 or a corresponding visual
field loss to less than 10 degrees in the better eye with the
best possible correction.
 Visual Impairment Includes low vision as well blindness
http://www.who.int/bulletin/volumes/82/11/en/844.pdf
DEFINITION
 This definition, based on best-corrected visual acuity,
excludes the large number of people worldwide who are
visually impaired due to uncorrected refractive error.
 Visual field constriction, independent of visual acuity, causes
functional impairment. The inclusion of visual field criteria in
the definition of blindness is recommended by the ICD-10
 Visual fields are difficult to assess and many studies have not
included visual field constriction in estimates of the
prevalence of visual impairment.
VISUAL FUNCTION
 In addition, visual function is comprised of many other
components. These include






visual field
color perception
stereoacuity
glare recovery
dark adaptation
contrast sensitivity function.
 These qualities of vision are not commonly assessed in
population based visual impairment prevalence studies
Levels of Visual Function
 1.- Normal vision
 2.- Moderate visual impairment
 3.- Severe visual impairment
 4.– Blindness
http://www.who.int/mediacentre/factsheets/fs282/en
/
Proposed revision of categories of visual impairment
Category
Worse than
Equal or better than
Moderate or visual
impairment
3/10 (0,3)
1/10 (0,1)
20/70
6/60
1/10 (0.1)
20/200
Severe Visual Impairment
6/60
1/10 (0.1)
20/200
3/60
1/20(0.05)
20/400
Blindness 3
3/60
1/20(0.05)
20/400
1/60
1/50(0.02)
5/300 (20/1200)
Blindness 4
1/60
1/50(0.02)
5/300 (20/1200)
Light perception
Blindness 5
No light perception
http://www.who.int/blindness/Change%20the%20Definition%20of%20Blindness.pdf
The distribution of blind all ages in the six
WHO Regions (millions)
Western pacific RegionPR
South east asia
Europe
Eastern mediterranean
America
Africa
0
http://www.who.int/blindness/table/en/index.html
2
4
6
8
10
12
14
http://www.who.int/blindness/causes/en/
http://www.who.int/mediacentre/factsheets/fs282/en
Causes of global blindness in millions of people
(WHO 2002)
Others
Onchocerciasis
Trachoma
Childhood blindness
Diabetic Retinopathy
Corneal opacities
AMD
Glaucoma
Cataract
0
5
10
15
20
A Foster S resnikoff.The impact of Vision 2020 on global blindness
Eye 2005; 19:1133-1135
Blindness Children
causes
1.4 million children under age 15 are blind.
The major causes of blindness in children vary widely from
region to region and are largely determined by socioeconomic
development, the availability of primary health care and eye
care services.
The available data suggests that, worldwide, corneal scarring
is the single most important cause of avoidable blindness in
childhood, followed by cataract and ROP.
http://www.who.int/bulletin/archives/79(3)227.pdf
http://www.vision2020kano.org/wp-content/uploads/2009/07/african-child-blind1-300x204.jpg
CATARACT
http://www.who.int/entity/blindness/causes/cata%20djib%2096.JPG
CATARACT
 The primary function of the ocular lens is to transmit light and
to focus it on the retina.
 A cataract occurs when the lens loses its clarity such that
visual acuity is compromised.
 Cataracts can result from genetic, metabolic, nutritional, or
environmental insults or can be secondary to other ocular or
systemic conditions, such as diabetes.
 The most important risk factor is age; age-related cataract
constitutes the great majority of all cataracts.
 Cataract remains the leading cause of blindness globally.
Tasman, Duane's Ophthalmology, Lippincott Williams & Wilkins ( 2005)
CATARACT
CATARACT TREATMENT
 There are no medications or eye drops to treat cataracts.
 Cataracts never get better on their own.
 Treatment for cataract is surgery to remove the cloudy lens
and replace it with clear artificial lens.
 The surgery is usually performed on an outpatient basis
under local anesthesia.
 Cataract surgery is one of the most cost-effective health
interventions.
GLAUCOMA
Author’s clinical photograph
GLAUCOMA
 Glaucoma is a group of diseases which results in progressive
damage to the optic nerve.
 Optic nerve damage leads to slow irreversible constriction of
peripheral vision and, if untreated, blindness.
 Optic nerve damage can be seen as excavation or ‘cupping’
of the optic nerve head.
 Glaucoma is often but not always associated with elevated
intraocular pressure.
GLAUCOMA
GLAUCOMA TREATMENT
Glaucoma can be controlled by lowering intraocular pressure
using
 Medication (eye drops)
 Laser therapy
 Surgery
AGE-RELATED
MACULAR DEGENERATION
http://www.aao.orgmedialibrary
AGE-RELATED
MACULAR DEGENERATION
 Age related macular degeneration (AMD) results in
progressive damage to the macula, the small area in the
retina responsible for sharp and central vision.
 The major risks for AMD are age and family history.
 AMD causes central vision loss. Central vision is critical for
reading and recognizing faces
 AMD is the leading cause of irreversible blindness in
industrialized countries.
AGE-RELATED
MACULAR DEGENERATION
AGE-RELATED
MACULAR DEGENERATION
 Dry AMD is characterized by progressive atrophy of the
retinal pigment epithelium, accumulation of retinal metabolic
products and loss of retinal photoreceptor function.
 Dry AMD can be slowed using a combination of Vit A, Vit E,
Vit C, Zinc and Copper.
 Wet AMD is characterized by bleeding underneath the retina
 Wet AMD is treated by injection of anti Vascular Endothelial
Growth Factor antibodies into the eye
DIABETIC RETINOPATHY
Author’s clinical photo
DIABETIC RETINOPATHY
 Diabetic retinopathy (DR) is the leading cause of blindness in
people of working age in industrialized countries.
 DR can be a complication of diabetes type1 or type 2.
 DR results from damage to the blood vessels of the retina,
the ‘photographic film’ of the eye.
 Initially, DR is asymptomatic. If not treated though it can
cause low vision and blindness.
 Risk factors associated with DR include duration of diabetes
and poor blood sugar control.
DIABETIC RETINOPATHY
TREATMENT
The best treatment for DR is prevention – control of blood
sugar
Once DR threatens vision treatments can include:
 Laser therapy to seal leaking blood vessels (focal laser)
 Laser therapy to reduce retinal oxygen demand (scatter
laser)
 Surgical removal of blood from the eye (vitrectomy)
Trachoma
http://www.aao.orgmedialibrary
TRACHOMA
http://www.vision2020.org/image/Diagrams
/global%20active%20may%202006.jpg
 Trachoma is caused by infection of the ocular surface by the
bacteria Chlamydia trachomatis serotypes A-C.
 Chlamydia trachomatis is endemic in many countries of
Africa Middle east, South America, and Asia.
 Trachoma can cause a severe inflammation of the ocular
surface resulting in scarring of the eyelids. This causes
eyelashes to grow in the wrong direction and rub the cornea
(clear front ‘window’ of the eye)
 Multiple reinfections can cause scarring and opacity of the
cornea.
http://www.cartercenter.org/images/BLINDch_web.gif
TRACHOMA TREATMENT
 The World Health Organization (WHO) recommends carrying
out an initiative called ‘SAFE’. SAFE stands for:
 Surgery to repair damage to the eye.
 Antibiotics to treat the infection.
 Face washing to reduce the spread of infection.
 Environmental changes, such as providing access to clean
water and suitable sanitation.
Mass antibiotic treatment with single-dose oral azithromycin
reduces the prevalence of active trachoma and ocular infection
in communities.
http://www.who.int/blindness/causes/trachoma/en/index.html
Onchocerciasis
http://www.unep.org/yearbook/2004/097.htm
ONCHOCERCIASIS
 Onchocerciasis, also known as river blindness, is caused by
the filarial nematode Onchocerca volvulus
 This worm is transmitted by the Simulium black fly, which
breeds in the rivers and streams of Africa, Brazil, Mexico, the
Middle East, and parts of Central America.
 Onchocerciasis is endemic in at least 27 sub-Saharan African
countries, and in Yemen
 Studies indicate that most eye clinical manifestations occur in
response to degenerating microfilariae and the release of
endosymbiotic Wolbachia bacteria.
http://whqlibdoc.who.int/publications/2010/9789241500722_eng.pdf
Onchocerciasis Treatment
 The treatment for onchocerciasis is ivermectin.
 A single dose of ivermectin needs to be taken annually to be
effective
 Targeting endosymbiotic Wolbachia species has emerged as
as a new approach in the control of onchocerciasis
 Onchocerca embryogenesis is completely dependent on the
presence of Wolbachia, studies of doxycycline therapy (100–
200 mg/d for 6 wk) have shown great promise.
Saint André A, Blackwell NM, Hall LR, Hoerauf A, Brattig NW,
Volkmann L, Taylor MJ, Ford L, Hise AG, Lass JH, Diaconu E,
Pearlman E. The role of endosymbiotic Wolbachia bacteria in
the pathogenesis of river blindness. Science. 2002 Mar
8;295(5561):1892-5
http://www.who.int/entity/pbd/blindness/onchocer
ciasis/en/onchocerca_volvulus.jpg
Retinopathy of Prematurity
http://www.aao.orgmedialibrary
ftp://ftp.nei.nih.gov/eye_exam/exam1
3_150.tif
Retinopathy of Prematurity (ROP)
 ROP is a disease that affect s a premature infants and is an important
cause of childhood blindness in developed countries.
 Retinopathy of prematurity (ROP) results from damage to the retina due
to incomplete development of retinal blood vessels prior to birth
 The primary risk factor for ROP is low gestational age at birth and the
smaller a baby is at birth the more likely that the baby is to develop
ROP.
 Major risk factors
• Low birthweight (less than 1500 grams)
• Low gestational age (32 weeks or less)
 Over 80% of infants born at less than 28 weeks’ gestational age
develop ROP and 60% of infants born at 28−31weeks develop ROP.
ftp://ftp.nei.nih.gov/eye_exam/exam12_150.tif
Retinopathy of Prematurity
 Successful treatment for ROP requires early detection and
timely laser therapy by skilled practitioners
 Despite improvements in detection and treatment, ROP
remains a leading cause of lifelong visual impairment among
children in developed countries
Vitamin A deficiency
http://motherchildnutrition.org/malnutrition/images/xerophthalmia.jpg
http://motherchildnutrition.org/malnutrition/images/xerophthalmia02.jpg
Vitamin A deficiency
 Vitamin A deficiency (VAD) can result in Xerophthalmia
(severe dryness and scarring of the eye), corneal ulceration
and perforation (keratomalacia) and night blindness
 VAD is the single most important cause of childhood
blindness in developing countries.
 An estimated 2.8 million preschool-age children are at risk of
blindness from VAD
 Vitamin A supplements at a cost of only 5 US cents a dose,
can reduce child mortality by up to 34% in areas where
Vitamin A deficiency is a public health problem
http://www.who.int/blindness/causes/priority/en/index4.html
Latin America and the Caribbean
 In Latin America and the Caribbean, cataract (opacification of
the lens) is the single most important cause of blindness;
cataract surgery has been shown to be one of the most cost
effective interventions of all health care interventions
http://www.who.int/bulletin/volumes/82/11/en/844.pdf
Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti
SP. Global data on visual impairment in the year 2002. Bull World Health Organ. 2004
Nov;82(11):844-51. Epub 2004 Dec 14.
Africa
 Blindness prevalence rates vary widely but the evidence
suggests that approximately 1% of Africans are blind.
 This region is home to approximately 7.1 of the world’s 38
million blind.
 Approximately half the blindness in Africa is due to cataract.
 Although trachoma has been declining in many areas of the
world, it still remains the second leading cause of blindness
in Africa.
http://www.who.int/bulletin/volumes/82/11/en/844.pdf
Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti SP. Global
data on visual impairment in the year 2002. Bull World Health Organ. 2004 Nov;82(11):844-51.
Epub 2004 Dec 14.
North America and Western
Europe
 Most adult visual impairment in North America and Western
Europe is related to age-related macular degeneration and
diabetic retinopathy. While both of these conditions are
subject to treatment, neither can be cured.
http://www.who.int/bulletin/volumes/82/11/en/844.pdf
Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram R, Pokharel GP, Mariotti
SP. Global data on visual impairment in the year 2002. Bull World Health Organ. 2004
Nov;82(11):844-51. Epub 2004 Dec 14.
Blindness challenges in
developing countries
http://www.who.int/entity/blindn
ess/causes/ChildhBlind%2096.
JPG
 Blindness is particularly devastating in the developing world
where it has a profound impact on the quality of life for the
blind person and his or her community.
 The majority of blind people in developing countries live in
remote areas, while most of the eye care providers and
hospitals are situated in the cities.
 Women and children face extra challenges, including limited
access to financial resources and health information, fewer
travel options, and less social support in seeking care.
http://www.cureblindness.org/world-blindness
http://www.who.int/entity/apoc/m
edia/onchocerciasis_blindness_
humb.jpg
Blindness in the developing world
 90% of blind people in the developing world can not work.
 50% report a reduced of social status and decision-making
authority.
 Blind people in the developing world are subject to low
employment, inadequate housing, substandard health care,
barriers to education, cultural activities, sports and recreation
 Life expectancy is half or less than age matched sighted
individuals
http://www.cureblindness.org/world-blindness/
Education
 Approximately 90% of visually impaired children in lowincome countries are deprived of an education. Lack of
infrastructure, affordable health care, production of
accessible and suitable school materials and qualified
teachers prevent visually impaired children from attending
school
http://www.dit.ie/mozambique-eyecare/developmentandeyecare/
http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2008/11/21/Blind-children.jpg
VISION 2020
 VISION 2020 is the global initiative for the elimination of
avoidable blindness, a joint program of the World Health
Organization (WHO)and the International Agency for the
Prevention of Blindness (IAPB) with an international
membership of NGOs, professional associations, eye care
institutions and corporations.
http://vision2020.org/main.cfm
The Guerrilla Eye Service of the UPMC Eye Center is
dedicated to eliminating barriers to eye care for patients
in the Western Pennsylvania area.
http://www.ophed.com/group/2205
http://www.kilimanjaro-blindtrust.org/pictures/school10.JPG
"Alone we can do so little, together we can
do so much.”
Helen Keller
References
 http://www.who.int/topics/blindness/en/
 http://www.who.int/mediacentre/news/releases/pr79/en/
http://whqlibdoc.who.int/bulletin/2001/issue3/79(3)227-232.pdf
 http://www.who.int/blindness/en/index.html
 http://www.nature.com/eye/journal/v19/n10/full/6701973a.html
 http://www.who.int/mediacentre/factsheets/fs282/en/index.html
 http://www.who.int/features/factfiles/vision/04_en.html
 http://www.who.int/features/factfiles/blindness/blindness_facts/en/in
dex7.html
 http://www.who.int/bulletin/volumes/82/11/en/844.pdf
References
 http://www.who.int/mediacentre/factsheets/fs282/en/
 http://www.who.int/bulletin/archives/79(3)227.pdf
 http://onlinelibrary.wiley.com/o/cochrane/clsysrev/articles/CD001860
/frame.html
 http://whqlibdoc.who.int/publications/2010/9789241500722_eng.pdf
 http://www.who.int/blindness/causes/priority/en/index4.html
 http://www.cureblindness.org/world-blindness
 http://www.vision2020.org/main.cfm
 http://www.dit.ie/mozambique-eyecare/developmentandeyecare/
 http://vision2020.org/main.cfm
References
 Resnikoff S, Pascolini D, Etya'ale D, Kocur I, Pararajasegaram
R, Pokharel GP, Mariotti SP. Global data on visual impairment in
the year 2002. Bull World Health Organ. 2004 Nov;82(11):84451. Epub 2004 Dec 14.
 Saint André A, Blackwell NM, Hall LR, Hoerauf A, Brattig NW,
Volkmann L, Taylor MJ, Ford L, Hise AG, Lass JH, Diaconu E,
Pearlman E. The role of endosymbiotic Wolbachia bacteria in
the pathogenesis of river blindness. Science. 2002 Mar
8;295(5561):1892-5
 Tasman, Duane's Ophthalmology, Lippincott Williams & Wilkins (
2005)
 Yanoff, Duker, Augsburger Ophthalmology, Mosby 2003.