Community Ophthalmology

Community Ophthalmology

Definition of blindness

WHO has defined blindness as “Visual acuity of less than 3/60 (Snellen) or inability to count fingers in daylight at a distance of 3 meters”.

In the Ninth Revision (1977) of the International classification of diseases (ICD), the visual impairment (maximum vision less than 6/18 Snellen) has been divided into 5 categories. Patients with the visual fields less than 10° are also labelled as blinds (Table 1)

Table 1 Categories of visual impairment WHO, (1977)
Categories of visual impairment Level of visual acuity (Snellen)
Normal vision
Low vision
0—6/6 to 6/18
1—Less than 6/18 to 6/60
Blindness 2—Less than 6/60 to 3/60
3—Less than 3/60 (FC at 3 m) to 1/60 (FC at 1m) or visual field between 5°and 10°
4—Less than 1/60 (FC at 1 m) to light perception or visual field less than 5°
5—No light perception

Avoidable blindness includes both preventable blindness (e.g. xerophthalmia blindness) and curable blindness (e.g. cataract blindness).

Magnitude of blindness
• The prevclance of blindness in developing countries range from 0.5 to 2 percent or higher, while the representative figure in developed countries is 0.05 to 0.3 per cent.

• The prevalence of blindness reported from India is 1.49 percent (WHO-NPCB 1986-89) and 1.1% (NPCB, 2001-2002)

Statewise incidence of blindness in India as per WHO-NPCB 1986-89 survey is as follows:
• Andhra Pradesh 1.50
• Assam 1.34
• Bihar 1.28
• Delhi 0.63 (Lowest)
• Gujarat 1.44
• Haryana 1.13
• Himachal Pradesh 0.87
• Karnatka 1.39
• Kerala 1.31
• Madhya Pradesh 2.01 (Highest)
• Maharashtra 1.64
• Punjab 0.73
• Tamil Nadu 1.65
• Uttar Pradesh 1.58

Causes of blindness
Developed countries versus developing countries. In developed countries, causes include: accidents, glaucoma, diabetes, vascular diseases, cataract, macular degeneration and hereditary conditions. While in developing countries the frequent causes are cataract, infectious diseases, xerophthalmia, injuries and glaucoma.

Causes of blindness in India: The major causes of blindness in elderly (70 and above) are senile cataract and age-related macular degeneration. See Table 2.

Table 2: Major causes of blindness in India.

NPCB Survey (2001-023)
Disease condition Percent blindness
Cataract 62.6
Refractive errors 19.7
Glaucoma 5.8
Postertor segment disorders 4.7
Surgical complications 1.2
Corneal blindness 0.9
Others 5.0
WHO-NPCB Survey (1986-89)
Disease condition Percent blindness
Cataract 80.1
Refractive errors 7.35
Glaucoma 1.7
Trachoma 0.39
Aphakic blindness 4.67
Corneal opacity 1.52
Others 4.25
ICMR survey (1971-74)
Disease condition Percent blindness
Cataract 55
Malnutrition 2
Glaucoma 0.5
Trachoma and associated infections 20
 Injuries 1.2
Small pox seaquele 3
Others 18

Childhood blindness
• Approximately 1.5 million children are blind in the world (WHO, 1992).
• Every year, approximately half a million children become blind i.e., about one every minute (WHO. 1992)
• Of the children going blind, about 60% die within one year (WHO, 1992)
• In about 70% of new cases (of childhood blindness), blindness is due to vitamin A deficiency (WHO, 1992).

Community OphthalmologyGlobal initiatives for prevention of blindness

Vision 2020: The Right to Sight

Objective: It is a global initiative to eliminate avoidable blindness by the year 2020.
Partners of vision 2020 initiative are WHO and task force of international NGOs.
Implementation will be through four phases of five year plans. Commencing in 2000,2005,2010 and 2015, respectively.

Basic strategies include:
• Disease prevention and control
• Training of eye health personnel
• Strengthening of existing eye care Infrastructures
• Use of appropriate and affordable technology, and
• Mobilization of resources
Global target diseases include: cataract, childhood, blindness, trachoma, refractive errors, and low vision and onchocerciasis.

Vision for the future (VFTF)
The International ophthalmology strategic plan to restore and preserve vision, directed and co-ordinated by the International Council of Ophthalmology has been launched as multi year, flexible and interactive programme.

National programme for control of blindness in India
NPCB in India was launched in the year 1976 with the objective to reduce prevalance of blindness.
Programme organization. NPCB operates through activities at central level, state level and district level.
District blindness control society (DBCS) with Deputy Commissioner as its chairman co-ordinates the activities at district level and ensures participation of the community and private sector.
‘Vision 2020: The Right to Sight, in India has been adopted under NPCB in Aug. 2002 with following strategies:
• Strengthening advocacy,
• Reduction of disease burden,
• Human resource development, and
• Eye care infrastructure development.
Target diseases identified for intervention in India include: cataract, childhood blindness, refractive errors and low vision, corneal blindness, diabetic retinopathy, glaucoma and trachoma (focal).