1. Ayesha Abdullah

4. 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

5. 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)

7. Definitions
There are 4 levels of visual function, according to the International Classification of Diseases -10
Normal vision
Moderate visual impairment
Severe visual impairment
Blindness
“low vision”
Visual
Impairment

8. 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 from fixation
Key words?

9. 6 5 4 3 2 1
visual acuity
less than 3/60

10. Which one is the better eye?
in the better eye
6/12
1/60
1/60
2/60

11. best possible correction

12. visual field loss
Better eye
less than 100

16. ICD VA VF (degrees) What it defines 6/6 – 6/18 > 20 Normal 1
Category VA VF
(degrees)
What it defines
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 5
NPL

17. Let’s examine a few scenariosVA
Visual Field
Rt eye (OD)
Lt eye (OS) 1
6/24
2/60 2
6/12
6/9
150
100 3
6/6
1/60 4
6/60 PL 5

18. EPIDEMIOLOGY OF BLINDNESS AND VISUAL IMPAIRMENT MAGNITUDE AND CAUSES

19. MAGNITUDE OF BLINDNESS & VI- 10 important facts
285 million people are estimated to be visually impaired worldwide: 39 million are blind and 246 have low vision.
About 90% of the world's visually impaired live in low-income settings.
82% of people living with blindness are aged 50 and above.
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.
80% of all visual impairment can be prevented or cured.

20. 10 important facts
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
Aging populations and lifestyle changes mean that chronic blinding conditions such as diabetic retinopathy & ARMD are likely to rise further
Women face a greater risk of vision loss than men
 Restorations of sight, and blindness prevention strategies are among the most cost-effective interventions in health care
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

21. Global distribution

22. Causes of blindness, Global level

23. Distribution of causes of blindness
DEVELOPED COUNTRIES
DEVELOPING COUNTRIES
Age-related macular degeneration (AMD)
Cataract
Diabetic retinopathy & glaucoma
Glaucoma & corneal opacity
Diabetic eye disease
( emerging) & AMD

24. “ Avoidable & unavoidable 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

26. Cataract

27. Glaucoma

29. Corneal opacity

30. Childhood blindness mortality & morbidity
Vitamin A deficiency
Normal
Keratomalacia

31. Trachoma

32. Age-related macular degeneration

33. H W By 30TH Aug 2016 NO submission would be accepted after due date.
Prevalence & top 3 major causes of blindness in Pakistan
How do people with blindness live their lives- Name of the person that you studied and their work- Not more than three lines
By 30TH Aug 2016
NO submission would be accepted after due date.