Ayesha Abdullah 17.08.2015

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

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)

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

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

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?

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

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

best possible correction

visual field loss Better eye less than 100

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

Let’s examine a few scenarios VA 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

EPIDEMIOLOGY OF BLINDNESS AND VISUAL IMPAIRMENT MAGNITUDE AND CAUSES

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

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

Global distribution

Causes of blindness, Global level

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

“ 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

Cataract

Glaucoma

Corneal opacity

Childhood blindness mortality & morbidity Vitamin A deficiency Normal Keratomalacia

Trachoma

Age-related macular degeneration

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.