Download - Ayesha Abdullah 08.09.2012
Ayesha Abdullah 08.09.2012
Why should Ophthalmology be taught and learnt?
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LEARNING OBJECTIVESBy 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
Azeem Khan a 65 year old person suffered from gradual loss of vision for the past two years. He now has difficulty in recognizing his own family members from a distance of about a yard. He recently retired as a school teacher.
Gul Mohammad a 04 year old child had a history of recurrent diarrohea and upper respiratory infections. He lost sight after having an episode of eye illness at the age of two. Currently he can only see light.
Haroon is a thirteen year old student of class five. He has been using spectacles since early childhood. Without his spectacles he cannot recognize a person a yard away.
Gulzar a 35 year old motor mechanic sustained injury to both his eyes in a bomb blast. Now he can see nothing but darkness.
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/icd10/browse/2010/en
Chapter Blocks Title
I A00-B99 Certain infectious and parasitic diseasesII C00-D48 NeoplasmsIII D50-D89 Diseases of the blood and blood-forming organs and certain disorders
involving the immune mechanismIV E00-E90 Endocrine, nutritional and metabolic diseasesV F00-F99 Mental and behavioural disordersVI G00-G99 Diseases of the nervous systemVII H00-H59 Diseases of the eye and adnexaVIII H60-H95 Diseases of the ear and mastoid processIX I00-I99 Diseases of the circulatory systemX J00-J99 Diseases of the respiratory systemXI K00-K93 Diseases of the digestive systemXII L00-L99 Diseases of the skin and subcutaneous tissueXIII M00-M99 Diseases of the musculoskeletal system and connective tissueXIV N00-N99 Diseases of the genitourinary systemXV O00-O99 Pregnancy, childbirth and the puerperiumXVI P00-P96 Certain conditions originating in the perinatal periodXVII Q00-Q99 Congenital malformations, deformations and chromosomal
abnormalitiesXVIII R00-R99 Symptoms, signs and abnormal clinical and laboratory findings, not
elsewhere classifiedXIX S00-T98 Injury, poisoning and certain other consequences of external causes
XX V01-Y98 External causes of morbidity and mortalityXXI Z00-Z99 Factors influencing health status and contact with health services
XXII U00-U99 Codes for special purposes
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?
visual acuity less than 3/60
6 5 4 3 2 1
in the better eye
1/606/12 2/601/60
Which one is
the better eye?
best possible correction
visual field loss Better eye less than 100
Blindness;09.01.09
Blindness;09.01.09
Blindness;09.01.09
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
Disease ——> Impairment ——> Disability ——> Handicap
Organ systemDamage Loss of
performance
Disadvantages to a person
because of the impairment &
disability
Organ IndividualInd-
Society
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
EPIDEMIOLOGY OF BLINDNESS AND VISUAL IMPAIRMENT; MAGNITUDE AND CAUSES
MAGNITUDE OF BLINDNESS & VI- 10 important facts
1. Approximately 314 million people suffer from serious visual impairment
2. Of these, 45 million people are blind and 124 million have low vision
3. Yet 75% of blindness is avoidable - i.e. treatable and/or preventable
4. 90% of visually impaired people live in developing countries
5. Infectious causes of blindness are decreasing as a result of public health interventions and socio-economic development. Blinding trachoma now affects fewer than 80 million people, compared to 360 million in 1985
10 important facts
6. 153 million people’s visual impairment is due to uncorrected refractive errors. In most cases, normal vision could be restored with eyeglasses
7. Aging populations and lifestyle changes mean that chronic blinding conditions such as diabetic retinopathy are now rising
8. Women face a greater risk of vision loss than men
10 important facts
9. Without effective, major intervention, the number of blind people worldwide is projected to increase to 76 million by 2020
10. Restorations of sight, and blindness prevention strategies are among the most cost-effective interventions in health care
10 important facts
Global distribution
Causes of blindness, Global level
Global causes of blindnessCause Number of blind
in million% of total
Cataract 25 50Glaucoma 6.7 13.4Refractive error 5 10Trachoma 3 6Vitamin A deficiency 0.5 1Other causes of childhood blindness
1 2
Age-related macular degeneration
1 2
Onchocerciasis 0.4 0.8Leprosy 0.3 0.6Corneal opacity other than from Trachoma & other causes
7.1 14.2
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
“ Avoidable & unavoidable blindness”
Blindness which could be either treated or prevented by known, cost-effective means Cataract Refractive errors Diabetic retinopathy
Unavoidable blindness Retinal causes of childhood blindness ARMD
Prevalence & major causes of blindness in Pakistan
Cataract
Glaucoma
Corneal opacity
Childhood blindnessmortality & morbidity
Vitamin A deficiency
Keratomalacia
Corneal xerosis
Bitot spot
Normal
Trachoma
Age-related macular degeneration
learning resources http://www.who.int/mediacentre/factsheets/fs282/en/
(WHO website) http://www.v2020.org/page.asp?section=000100010002
( Vision 2020 website) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2486591/pdf/bullwho00405-0112.pdf http://www.who.int/classifications/apps/icd/icd10online/
(ICD-10) http://www.who.int/blindness/Change%20the%20Definition%20of%20Blindness.pdf
Textbook Johnson GJ, Minassian DC, Weale RA, WestSk
(editors). Prevalence, incidence and distribution of visual impairment. In The epidemiology of eye disease, 2nd Ed. London. Arnold 2003; 3-5