Visual Impairment and Blindness
Dr. Tabassum Nawab Assistant Professor
Department of Community Medicine JNMC, AMU, Aligarh
Objectives
¤ WHO definition of blindness
¤ Problem statement
¤ Causes
¤ Epidemiological determinants
¤ Changing concepts in eye health care
¤ Prevention
¤ NPCBVI
¤ Vision 2020: The Right to Sight
¤ World Sight Day
Definition of Blindness
¤ 65 definitions of blindness (publication of WHO in 1966)
¤ 25th WHA in 1972 considered the need for generally acceptable definition of blindness and visual
impairment for national and international comparability
WHO definition
¤ “
visual acuity of less than 3/60 (Snellen’s chart) or its equivalent ” or
¤ “ Inability to count fingers in daylight at a
distance of 3 meters. ”
Categories of visual impairment
WHO-ICD Visual Acuity NPCB
Categories
No VI 0 > 6/18
Low vision 1 <6/18 - 6/60 Low vision
2 <6/60 - 3/60 Economic/ Legal Blindness
Blindness 3 <3/60(FC 3m) - 1/60(FC 1m) Social Blindness 4 <1/60(FC 1m) - PL Manifest Blindness
5 No PL Absolute Blindness
5
FC= Finger counting, VI= Visual Impairment, PL= Perception of light
Problem statement
¤ World-
¤ 2.2 billion people worldwide are visually disabled/blind out of which 1 billion have preventable/curable cause
¤ Prevalence- 0.2% or less to 1%
¤ 80% of blindness is avoidable.
¤ In SEAR-
¤ Prevalence- 0.8%(0.3-1.5)
¤ 90% of which is avoidable
¤ In India-
¤ Prevalence- 0.7%
¤ About 82 per cent of all people who are visually impaired are aged 50 years and older, while this age group comprises
about 20 per cent of the world's
population.
CAUSES OF BLINDNESS-World
¤ In developed countries: accidents, glaucoma, diabetes, vascular disease (HT), cataract, degeneration of ocular tissues, hereditary conditions
¤ In SEAR: cataract(50-80%), RE, emerging causes- glaucoma, ARMD, diabetic retinopathy, corneal ulcer, ocular trauma
¤ Childhood blindness: xerophthalmia, cong. Cataract, cong. Glaucoma, OA due to meningitis, ROP,
uncorrected RE
Causes of blindness- India
Cataract 62.6%
Refractive Error 19.7%
Corneal Blindness 0.9%
Glaucoma 5.8%
Surgical Complication 1.2%
Posterior Segment Disorder 4.7%
Others 5%
Source: 2001-02 National survey on blindness
Epidemiological determinants
¤ Age
¤ RE, Trachoma, conjunctivitis, malnutrition at younger ages
¤ Cataract, glaucoma, diabetes at middle age
¤ Injuries and accidents at any age
¤ Sex
¤ Cataract, trachoma and conjunctivitis higher among females
¤ Malnutrition – Vitamin A deficiency
Epidemiological determinants
¤ Occupation
¤ Occupational exposure to dust, airborne particles, flying objects, gases, fumes, radiation- eye injuries
¤ Premature cataract - due to X-ray exposure
¤ Social class
¤ Prevalence twice more in poorer socioeconomic class
¤ Other social factors
¤ Treatment by quacks, poverty, ignorance, low
standard of hygiene, inadequate healthcare services
Changing concepts in eye health care
¤ Acute intervention – comprehensive eye health care which includes
1) Primary eye care
2) Epidemiological approach 3) Team concept
4) Establishment and enhancement of national
programme
Primary eye care
¤ Cornerstone-
¤ The promotion and protection of eye health,
¤ on-the-spot treatment for the commonest eye diseases,
¤ The final objective of primary eye care is to
¤ increase the coverage and quality of eye health care through primary health care approach
¤ improve the utilization of existing resources.
Epidemiological approach
¤ involves studies at the population level
¤ measurement of the incidence, prevalence of diseases and their risk factors.
¤ The local epidemiological situation – will determine the action needed.
Team concept
In developing countries-
¤ As eye-specialist per population are scarce
¤ village health guides, ophthalmic assistants,
multi-purpose workers, and voluntary agencies- used to fill many gaps in provision of care
National program
Formed in 2004
Decentralization in 1994-95 Taken under NRHM in 2007 Launched in 1976 Incorporated TCP
Prevention of blindness
1. Initial assessment
¤ Magnitude
¤ geographic distribution
¤ causes
Essential for setting priorities &
development of intervention program
2. Methods of intervention
a) Primary eye care
§ Based on primary health care
§ Certain eye condition manageable locally
§ Promotion of hygiene, sanitation, good dietary habits and general safety.
b) Secondary care
§ Management of common blinding condition.
§ Involves PHC, district hospitals with eye clinics &
mobile camps
c) Tertiary care
§ At tertiary care centres, regional centres, medical colleges etc.
Methods of intervention
d) Specific programmes
¤ Trachoma control
¤ School Eye Health Services
¤ Vit-A Prophylaxis
¤ Occupational eye health services
Initial assessment & methods of intervention
should be followed by long term follow-up
measures and evaluation
Trachoma control
¤ Mass campaigns with topical tetracycline and the improvement of socio-economic conditions (thus improved hygiene and sanitation) have markedly reduced the severity of trachoma and associated bacterial conjunctival
infections.
¤ The Trachoma Control Programme launched in India in 1963 was merged with the National
Programme for the Control of Blindness in 1976.
School eye health services
¤ Children are screened and treated for defects such as refraction errors, squint, amblyopia, trachoma.
¤ Health education - an important component
¤ Students should be taught to practise the principles of good posture, proper lighting, avoidance of
glare, proper distance and angle between the books and the eyes.
¤ Use of suitably readable type style in textbooks should be encouraged.
Vit A prophylaxis
Under the vitamin A distribution scheme in India,
¤ 200,000 IU of vitamin A are given orally at 6-
monthly intervals between the ages 1-6 years.
¤ To be able to control xerophthalmia, the whole family should be kept under surveillance for one year and children for 5 years
Occupational eye health services
¤ Education on the prevention of occupational eye hazards and the use of protective devices in some occupations (like welding) is essential.
¤ Prevention of accidents in factories –
¤ improvement in the safety features of machines,
¤ proper illumination of the working area,
¤ select workers with the requisite alertness and good vision, and
¤ encourage the use of protective devices
3. LONG-TERM MEASURES
¤ Aimed at improving the quality of life and modifying or attacking the factors responsible for the persistence of eye health problems, e.g.,
¤ poor sanitation,
¤ lack of adequate safe water supplies,
¤ little intake of foods rich in vitamin A,
¤ lack of personal hygiene, etc.
¤ Health education –
¤ to create community awareness of the problem;
¤ to motivate the community, to accept total eye health care programmes, and
¤ to secure community participation.
National Programme for Control of
Blindness and Visual Impairment
NPCBVI
¤ Launched in 1976 as 100% centrally sponsored scheme (now 60:40 in all states and 90:10 in NE states)
¤ Goal to reduce prevalence of blindness to 0.3%
by 2020.
Vision 2020: Right to Sight
¤ A global initiative to eliminate avoidable blindness was launched by WHO on 18th Feb. 1999.
¤ The objective of Vision 2020 is to assist member
countries in developing sustainable systems which will enable them to eliminate avoidable blindness from major causes by the year 2020
Target diseases in India-
¤ Cataract
¤ Xerophthalmia and other childhood blindness
¤ Refractive errors and low vision
¤ Corneal blindness
¤ Diabetic retinopathy
¤ Glaucoma
¤ Trachoma (locally)
Core strategies
¤ Disease control
¤ Human resource development
¤ Infrastructure and appropriate
technology development.
Vision 2020-
proposed structure
World Sight Day
¤ World Sight Day is an annual day of
awareness held on the second Thursday of October, to focus global attention on blindness and vision impairment.
¤ World Sight Day 2020 is on 8 October 2020.
