Ayesha Abdullah 17.08.2015

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LEARNING OBJECTIVES

By the end of this lecture the students should be able to:

• Define blindness, visual impairment & low vision according to the WHO- ICD-10 classification

• Critically evaluate the definition & its implications

• Describe the global burden of blindness & visual impairment.

• Identify the major causes of blindness at global and national level.

• Recognize the impact of blindness on the life of the individual and the society

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Definition of blindness

• Blindness is defined in different ways in different countries according to the purpose of definition i.e legal, social, clinical etc

• WHO recommends the ICD-101 –based definition

• In Pakistan we use the same

1. International Statistical Classification of Diseases & related health problems, 10th revision (ICD-10) 5

http://apps.who.int/classifications/apps/icd/icd10online2006/ 6

Definitions • There are 4 levels of visual function, according to

the International Classification of Diseases -10 1. Normal vision2. Moderate visual impairment3. Severe visual impairment4. Blindness

“low vision” Visual Impairment

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Definition of blindness

(ICD-10,Visual impairment (VI) categories 3, 4 & 5)

• Blindness is defined as a visual acuity (VA) of less than 3/60 (20/400) in the better eye with best possible correction

Or • A visual field in the better eye to less

than 100 from fixation

• Key words?

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• visual acuity • less than 3/60

6 5 4 3 2 1

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• in the better eye

1/606/12 2/601/60

Which one is

the better eye?

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• best possible correction

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• visual field loss • Better eye• less than 100

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ICDCategory

VA VF(degrees)

What it defines

0 6/6 – 6/18 > 20 Normal

1 <6/18-6/60 < 20 MVI

2 <6/60-3/60 SVI

3 <3/60-1/60 <10 B

4 <1/60-PL B

5 NPL B

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Let’s examine a few scenarios

VA Visual Field

Rt eye (OD)

Lt eye (OS)

Rt eye (OD)

Lt eye (OS)

1 6/24 2/602 6/12 6/9 150 100

3 6/6 1/604 6/60 PL5 2/60 2/60

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EPIDEMIOLOGY OF BLINDNESS AND VISUAL

IMPAIRMENT MAGNITUDE AND CAUSES

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MAGNITUDE OF BLINDNESS & VI- 10 important facts

1. 285 million people are estimated to be visually impaired worldwide: 39 million are blind and 246 have low vision.

2. About 90% of the world's visually impaired live in low-income settings.

3. 82% of people living with blindness are aged 50 and above.

4. Globally, uncorrected refractive errors are the main cause of moderate and severe visual impairment; cataracts remain the leading cause of blindness in middle- and low-income countries.

5. 80% of all visual impairment can be prevented or cured.

http://www.who.int/mediacentre/factsheets/fs282/en/http://www.who.int/features/factfiles/blindness/blindness_facts/en/index9.html 19

6. The number of people visually impaired from infectious diseases has reduced in the last 20 years according to global estimates work. Blinding trachoma now affects fewer than 80 million people, compared to 360 million in 1985

7. Aging populations and lifestyle changes mean that chronic blinding conditions such as diabetic retinopathy & ARMD are likely to rise further

8. Women face a greater risk of vision loss than men

9.  Restorations of sight, and blindness prevention strategies are among the most cost-effective interventions in health care

10. An estimated 19 million children are visually impaired. Of these, 12 million children are visually impaired due to refractive errors, a condition that could be easily diagnosed and corrected. 1.4 million are irreversibly blind for the rest of their lives

10 important facts

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Global distribution

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Causes of blindness, Global level

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Distribution of causes of blindness

DEVELOPED COUNTRIES DEVELOPING COUNTRIES

Age-related macular degeneration (AMD)

Cataract

Diabetic retinopathy & glaucoma

Glaucoma & corneal opacity

Cataract Diabetic eye disease ( emerging) & AMD

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“ Avoidable & unavoidable blindness”

• Avoidable Blindness • That can be either treated or prevented

by known, cost-effective means• Cataract• Refractive errors• Diabetic retinopathy

• Unavoidable blindness• Retinal causes of childhood blindness• ARMD

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Cataract

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Glaucoma

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Corneal opacity

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Childhood blindnessmortality & morbidity

• Vitamin A deficiency

Keratomalacia

Normal

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Trachoma

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Age-related macular degeneration

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H W

msqheartline@hotmail.com

By Sunday 23rd Aug 2015

NO submission would be accepted after due date.

1. Prevalence & top 3 major causes of blindness in Pakistan

2. How do people with blindness live their lives- Name of the person that you studied and their work- Not more than three lines

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