2. Low Vision (WHO definition)
• “A person with low vision is one who has
impairment of visual functioning even after
treatment and/or standard refractive
correction, and has a visual acuity of less than
6/18 to light perception, or a visual field less
than 10 degrees from the point of fixation, but
who uses, or is potentially able to use, vision
for the planning and/or execution of a task.”
3. Blindness
WHO definition of blindness
-the best corrected visual acuity in the better eye
less than 3/60 and/or visual field less than 10
degree from the point of fixation.
4. 2 main categories of blindness
1. Partial blindness:
- have very limited vision
2. Complete blindness:
- can not see anything and do not see light
6. 1. Economic blindness: Inability of a person to
count fingers from a distance of 6 meters or
20 feet
2. Social blindness: Vision 3/60 or diminution of
field of vision to 10°
3. Manifest blindness: Vision 1/60 to just
perception of light
4. Absolute blindness: No perception of light
5. Curable blindness: That stage of blindness
where the damage is reversible by prompt
management e.g. cataract
7. 6. Preventable blindness: The loss of blindness
that could have been completely prevented by
institution of effective preventive or
prophylactic measures e.g. xerophthalmia,
trachoma and glaucoma
7. Avoidable blindness: The sum total of
preventable or curable blindness is often
referred to as avoidable blindness.
8. Magnitude of the problem
• Global:
- It is estimated that 180 million people are visually
impaired of them 45 million people are blind
• India:
-The prevalence of blindness is 77% and 68 lakh
people are blind as per W.H.O. statistics.
9. Causes of Blindness
1. Congenital/ Developmental defect (Leading causes of
childhood blindness)
-Xerophthalmia, congenital cataract, congenital glaucoma
& optic atrophy
2.The leading causes are-
-DM, Glaucoma, vascular disease, Macular degeneration,
and accident (such as chemical burns or sports injury)
3. Worldwide leading causes of blindness are-
-cataract, trachoma, leprosy and vit-A deficiency.
4. Other causes include:-
-Blocked blood vessels, complication of premature birth
(Retrolental fibroplasia), complication of eye surgery
10. INDIA
2001-02 National survey on blindness
Main causes of blindness are as follows:
1. Cataract 62.6%
2. Uncorrected Refractive error 19.7%
3. Glaucoma 5.8%
4. Posterior segment pathology 4.7%
5. Corneal blindness 0.9%
6. Other causes 6.2%
7. Surgical complication 1.2%
8. Estimated National Prevalence of childhood
Blindness/ Low Vision is 0.80 per thousand.
11. Epidemiological determinants
1. Age:
– In children & young: Refractive error, trachoma,
conjunctivitis, malnutrition.
– In adults: cataract, refractive error, glaucoma, DM
2. Sex:
– Higher prevalence of trachoma, conjunctivitis and
cataract in women leading to higher prevalence of
blindness in women
12. 3. Malnutrition:
– Infectious diseases of childhood especially measles &
diarrhoea
– PEM
– Severe blinding corneal destruction due to vit. A
deficiency in first 4 to 6 years of life.
4. Occupation:
– People working in factories, workshop, industries are
prone to eye injuries because of exposure to dust,
airborne particles, flying objects, gases, fumes,
radiation.
13. 5. Social class:
– Surveys indicate that blindness twice more
prevalent in poorer classes than in the well to do.
6. Social factors:
– Basic social factors are ignorance, poverty, low
standards of personal and community hygiene and
inadequate health care services.
14. Prevention of Blindness
The components for action in national programmes for the
prevention of blindness comprise the following:
Initial assessment
Methods of intervention
– primary eye care
– secondary care
– tertiary care
– specific programmes
Long term measures
15. Initial assessment
– Assess the magnitude, geographic distribution,
and causes of blindness within the country by
prevalence survey.
16. Methods of Intervention
Primary eye care
– Wide range of eye conditions can be treated or prevented
at grass root level by locally trained health workers who
are first to make contact with the community.
– They are also trained to refer the difficult cases to the
nearest PHC or district hospital.
– Their activities also involve promotion of personal hygiene,
sanitation, good dietary habits and safety in general.
17. Secondary care:
– Involves definitive management of common
blinding conditions as cataract, trichiasis,
entropion, ocular trauma, glaucoma.
– It is provided in PHCs and district hospitals
where
eye depts are established.
– May involve the use of mobile eye clinics
18. Tertiary care
– Established in the national or regional capitals and
are often associated with medical colleges and
institutes of medicine.
– Provide sophisticated eye care such as retinal
detachment surgery, corneal grafting which are
not available in the secondary centres.
– Other measures of rehabilitation comprise
education of blind in the special schools &
utilisation of their services in the gainful
employment.
19. Specific programmes
– Trachoma control
– School eye health services: Screening and
treatment , Health education
– Vit.A prophylaxis
– Occupational eye health services
20. Long term measure
– Aimed at improving quality of life
– Modifying or attacking the factors responsible
for the persistence of eye health problems.
• Poor sanitation
• Lack of adequate safe water supply
• Poor nutrition
• Lack of personal hygiene
21. National Programme for Control of
Blindness (NPCB)
• Was launched in the year 1976 as a 100 % centrally
sponsored programme
• It incorporates the earlier trachoma control
programme started in the year 1968
• Goal: To reduce the prevalence of blindness
from 1.4 to 0.3% by 2020.
• In the year 2006-07: prevalence was 1.0%
22. Strategy of Programme
• Strengthening eye care service delivery
• Developing human resource for eye care
• Promoting out-reach activities & public awareness
• Developing institutional capacity
• Increase and expand research
• Participation of NGOs
23. School Eye Screening Programme
• 6-7 % children age to 10-14 years – Eye sight
problem
• Children – screened by school teachers.
• Suspected refractive error are seen by
ophthalmic assistants & spectacles are prescribed
free of cost.
24. Vision 2020: The Right to Sight
-Is the Global initiative to reduce avoidable
(Preventable and curable) blindness by the year 2020.
-It was launched in 1999 and a joint programme of WHO
and IAPB(International Agency for the Prevention of
blindness).
• Main features:
– Target Diseases
– Human resource development and infrastructure and
technology development.
26. Management of Blindness
1. The treatment of blindness depends on the cause of
blindness.
2. Blindness due to nutritional deficiency: It can be addressed
by dietary changes.
3. Visual impairment due to refractive error: It can be
addressed by doing a refraction and providing appropriate
spectacles.
4. Inflammatory and infectious causes of blindness can be
treated with medication in the form of drops or pills.
5. Most of people are blind due to cataract: In these patients,
cataract surgery would, in most cases, restore their sight.
