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

Why should Ophthalmology be taught and learnt?

1. Approximately 314 million people suffer from serious visual impairment million people are blind and 124 million have low vision 3. 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. Blinding trachoma now affects fewer than 80 million people, compared to 360 million in 1985

million people’s visual impairment is due to uncorrected refractive errors. In most cases, normal vision could be restored with eyeglasses 7. Aging populations, lifestyle changes rising incidence of chronic blinding conditions such as diabetic retinopathy 8. Women face a greater risk of vision loss than men

9.Without effective, major intervention, the number of blind people worldwide is projected to increase to 76 million by Restorations of sight, and blindness prevention strategies are among the most cost-effective interventions in health care

 Why define?  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-10 1 –based definition  In Pakistan we use the same 1. International Statistical Classification of Diseases & related health problems, 10 th revision (ICD-10)

ChapterBlocksTitle IA00-B99Certain infectious and parasitic diseases IIC00-D48Neoplasms IIID50-D89 Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism IVE00-E90Endocrine, nutritional and metabolic diseases VF00-F99Mental and behavioural disorders VIG00-G99Diseases of the nervous system VIIH00-H59Diseases of the eye and adnexa VIIIH60-H95Diseases of the ear and mastoid process IXI00-I99Diseases of the circulatory system XJ00-J99Diseases of the respiratory system XIK00-K93Diseases of the digestive system XIIL00-L99Diseases of the skin and subcutaneous tissue XIIIM00-M99Diseases of the musculoskeletal system and connective tissue XIVN00-N99Diseases of the genitourinary system XVO00-O99Pregnancy, childbirth and the puerperium XVIP00-P96Certain conditions originating in the perinatal period XVIIQ00-Q99 Congenital malformations, deformations and chromosomal abnormalities XVIIIR00-R99 Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified XIXS00-T98Injury, poisoning and certain other consequences of external causes XXV01-Y98External causes of morbidity and mortality XXIZ00-Z99Factors influencing health status and contact with health services XXIIU00-U99Codes for special purposes

ICD CategoryVAVF (degrees) What it defines 06/6 – 6/18> 20Normal 1<6/18-6/60< 20MVI 2<6/60-3/60SVI 3<3/60-1/60<10B 4<1/60-PLB 5NPLB

(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 10 0 from fixation  Key words?

 visual acuity  less than 3/

 in the better eye 1/606/122/601/60 Which one is the better eye?

 best possible correction

 visual field loss  Better eye  less than 10 0

Disease ——> Impairment ——> Disability ——> Handicap Organ system Damage Loss of performance Disadvantages to a person because of the impairment & disability Organ Individual Ind- Society

VAVisual Field Rt eye (OD) Lt eye (OS) Rt eye (OD) Lt eye (OS) 16/242/60 26/126/ /61/60 46/60PL 52/60

CauseNumber of blind in million % of total Cataract2550 Glaucoma Refractive error510 Trachoma36 Vitamin A deficiency0.51 Other causes of childhood blindness 12 Age-related macular degeneration 12 Onchocerciasis Leprosy Corneal opacity other than from Trachoma & other causes

DEVELOPED COUNTRIESDEVELOPING COUNTRIES Age-related macular degeneration (AMD) Cataract Diabetic retinopathy & glaucoma Glaucoma & corneal opacity CataractDiabetic eye disease ( emerging) & AMD

 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

?

 Vitamin A deficiency Keratomalacia Corneal xerosis Bitot spot Normal

DIABETIC RETINOPATHY

 A person has a visual acuity of 3/60 in the right eye and 6/60 in the left eye according to the WHO (ICD-10) classification he  Has moderate visual impairment  Is a blind person  Is blind in the left eye  Is blind in the right eye  Is normal

n/ (WHO website) n/ ( Vision 2020 website) /pdf/bullwho pdf 591/pdf/bullwho pdf ne/ (ICD-10) ne/ efinition%20of%20Blindness.pdf efinition%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, 2 nd Ed. London. Arnold 2003; 3-5