Blindness: Definition, Prevalence, Causes, Risk factors, Symptoms, and Prevention (Vision 2020)


Blindness – inability to see, ranges from the simple impairments in seeing objects, to a total lack of sight.

The International Classification of Diseases 11 (2018) classifies vision impairment into two groups, distance and near presenting vision impairment.

Distance vision impairment:

Mild – presenting visual acuity worse than 6/12
Moderate – presenting visual acuity worse than 6/18
Severe – presenting visual acuity worse than 6/60
Blindness – presenting visual acuity worse than 3/60

Near vision impairment:

Presenting near visual acuity worse than N6 or M.08 with existing correction.


Globally the leading causes of vision impairment are:

1. uncorrected refractive errors

2. cataract

3. age-related macular degeneration

4. glaucoma

5. diabetic retinopathy

6. corneal opacity

7. trachoma.

8. Measles

9. Onchocerciasis also known as River Blindness

Risk factors



History of blindness in the family


Malnutrition he lack of vitamin A

Prematurity/Premature babies

Poor hygiene (trachoma)

Adavancing age

Poisoning e.g. methanol poisoning


Eye surgery

A blind woman


Globally, it is estimated that at least 2.2 billion people have a vision impairment or blindness, of whom at least 1 billion have a vision impairment that could have been prevented or has yet to be addressed.

This 1 billion people includes those with moderate or severe distance vision impairment or blindness due to unaddressed refractive error (123.7 million), cataract (65.2 million), glaucoma (6.9 million), corneal opacities (4.2 million), diabetic retinopathy (3 million), and trachoma (2 million), as well as near vision impairment caused by unaddressed presbyopia (826 million).

In terms of regional differences, the prevalence of distance vision impairment in low- and middle-income regions is estimated to be four times higher than in high-income regions.The leading causes of vision impairment are uncorrected refractive errors and cataracts. The majority of people with vision impairment are over the age of 50 years.

There is some variation in the causes across countries. For example, the proportion of vision impairment attributable to cataract is higher in low- and middle-income countries than high-income countries.

In high income countries, diseases such as diabetic retinopathy, glaucoma and age-related macular degeneration are more common. Among children, the causes of vision impairment vary considerably across countries. For example, in low-income countries congenital cataract is a leading cause, whereas in high income countries it is more likely to be retinopathy of prematurity.

According to the last national blindness and visual survey in Nigeria, 3,597,552 individuals aged ≥40 years had mild/moderate visual impairment and 1,025,315 had severe visual impairment/blindness in Nigeria as at 2008.

There was a projection that by 2020 the number would have risen to 4,974,995 for individuals with mild/moderate visual impairment and 1,442,554 for individuals with severe visual impairment/blindness. Also, 84% of all causes of blindness were either preventable or treatable. Refractive error, cataract, glaucoma, corneal opacity excluding trachoma were the commonest causes..

Vision 2020

VISION 2020 is a global initiative that aims to eliminate avoidable blindness by the year 2020. The initiative was also aimed at reducing the global burden of blindness from 75 million to < 25 million people by 2020. It was launched on 18 February 1999 by the World Health Organization together with the more than 20 international non-governmental organisations involved in eye care and prevention and management of blindness that comprise the International Agency for the Prevention of Blindness (IAPB). VISION 2020 is a partnership that provides guidance, technical and resource support to countries that have formally adopted its agenda. Core strategies • Disease control: facilitate the implementation of specific programmes to control and treat the major causes of blindness. • Human resource development: support training of ophthalmologists and other eye care personnel to provide eye care. • Infrastructure and appropriate technology development: assist to improve infrastructure and technology to make eye care more available and accessible INTERVENTIONS

The evidence now available for Nigeria shows that a significant proportion of those with mild and moderate visual impairment can immediately benefit from optical and refraction services, whereas most of those with severe visual impairment or blindness are in need of cataract surgery.

VISION2020 emphasizes the need to strengthen both services if the elimination of avoidable blindness is to become a reality. With 80% of blindness being avoidable and the success of approaches like cataract surgery being established, effective implementation of VISION2020 may contribute toward development and economic productivity.

Special efforts are needed to target women, persons living in rural areas, and persons who are poorly educated. Regional variations need to be addressed so that priority attention is given to those regions/ zones that have high magnitude and lack adequate surgical or optical services within a system that delivers comprehensive eye care to populations.

In Nigeria, the National Eye Health Program (formerly, National Program for the Prevention of Blindness) works with all stakeholders (governments and NGDOs) in establishing, strengthening and advancing the Vision 2020 program with shared responsibilities defined at the national, zonal, state, local, and community levels. The aim of this intervention was to reduce the country’s blindness prevalence rate to about 0.5% in most communities in the country.

To compliment this initiative led to the establishment of the Lagos State Blindness Prevention Programme (LSBPP) in the year 2000 with the goal of eliminating avoidable blindness due to diseases such as cataract, glaucoma, refractive errors, childhood blindness in Lagos State. The objective of this initiative is to reduce the blindness prevalence in Lagos State from 1.1% – 1.2% to 0.5% over a five year period.

The initial policy focus of the programme was to reach the people in the 20 local government areas of the State with the main strategy being outreach screening programs and surgical expeditions thereby bringing succour to the less privileged who could not ordinarily afford the cost of orthodox treatment and in so doing alleviating poverty in the society.

In order to further enhance the program and strengthen the delivery of eye care in the State, in 2008 an action plan was articulated to develop a comprehensive eye health care system in the State at all levels.

Another initiative, the School Eye Health Screening programme was launched in year 2006 as one of the ways of reducing the burden of childhood blindness as a cause of avoidable blindness in Lagos State.

After the initial screening of selected Primary Schools in 2006, a State policy was put in place to continue to screen pupils in Lagos State covering all the LGAs/LCDAs. This has continued till date. From inception till date April 2011, a total of 44,805 pupils were screened different Local Government Areas of the State.

In an effort to provide eye care services to the population, the governments of two neighbouring states (Sokoto and Kebbi) in North Western Nigeria are collaborating with international NGDOs in the provision of eye health services.

In Sokoto state that collaborates with one NGDO, vertical eye care services (onchocerciasis-1996, cataract-2000 and trachoma-2003,) were integrated into a program named the Sokoto state eye care program that took off in 2005.

In neighbouring Kebbi state however, the collaboration was with two NGDOs each focused on different blinding conditions: that is onchocerciasis control program, “free” cataract surgery and trachoma control programs, that took off in 1996, 2002 and 2003, respectively. While indigenous personnel implement the programs on onchocerciasis and trachoma, nonindigenous ophthalmologist provides cataract service.


VISION FOR THE FUTURE-NIGERIA: The Ophthalmological Society of Nigeria’s Strategic Plan to Preserve and Restore Vision in Nigeria based on the blue print of the International Council for Ophthalmology Vision for the Future.

In line with the Strategic Plan of the International Council of Ophthalmology, the central purpose of VISION FOR THE FUTURE-NIGERIA is to eliminate blindness and low vision that result from preventable and treatable eye disease for people throughout Nigeria.

Participants will work to promote access to high-quality, affordable eye care and to promote access by ophthalmologists and others to the training and continuing education they need to provide appropriate eye care to people throughout Nigeria.

With a mission to preserve and restore vision, Vision For The Future-Nigeria, encourages activities to enhance Ophthalmological Education and Training, Ophthalmology Continuing Education, Eye Care Guidelines and Recommendations, Advocacy for the Preservation and Restoration of Vision, Research in Ophthalmology and Vision and the highest level of Ethical standards in the practice of Ophthalmology.


It is obvious that there are actions already at play in the reduction of the burden of blindness in Nigeria, yet, there are no records to show how far we have gone at attaining the VISION 2020 goal and here is 2020. The battle against blindness is still a far cry from victory and we can’t rest on our oars despite the fact that there are other myriads of issues plaguing Nigeria and the world at large.







6. Featured Image = WHO

This article was written by: ODEMUYIWA ADEYEMI J (MBBS, Ibadan)


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