Visual impairment and blindness (2024)

Overview

Sight, the most dominant of our senses, plays a crucial role in all facets and stages of our lives. We take vision for granted, but without vision we have difficulty learning, walking, reading, going to school and working.

Visual disturbances occur when an eye disease affects the visual system and its visual functions. Everyone, if they live long enough, will experience at least one eye disease in their lifetime that requires appropriate care.

Visual impairment has serious consequences for the individual throughout the life course. Many of these consequences can be mitigated with timely access to high-quality eye care. Eye diseases that can cause vision impairment and blindness – such as cataracts or refractive errors – are the main focus of eye care strategies for good reason; Nevertheless, the importance of eye diseases that do not usually cause visual impairment – ​​such as dry eye or conjunctivitis – should not be overlooked. These relationships often belong to themain causesfor presentation for eye care services.

Reasons

Worldwide, the leading causes of visual impairment and blindness are:

• refractive error
• staar
• diabetic retinopathy
• glaucoma
• age-related macular degeneration.

There is considerable variation in the causes of visual impairment between and within countries, depending on the availability of eye care services, their affordability and the education of the population. For example, the proportion of visual impairment attributable to unoperated cataract is higher in low- and middle-income countries. In high-income countries, diseases such as glaucoma and age-related macular degeneration are more common.

In children, congenital cataract is a leading cause of visual impairment in low-income countries, while in middle-income countries it is more likely to be retinopathy of prematurity.

Uncorrected refractive errors remain a major cause of visual impairment among children and adults in all countries.

Distribution

At least 2.2 billion people worldwide have vision impairment at near or distance. In at least 1 billion – or almost half – of these cases, vision loss could have been prevented or has not yet been treated.

Among these 1 billion people, the leading conditions causing visual impairment or distance blindness are cataract (94 million), refractive error (88.4 million), age-related macular degeneration (8 million), glaucoma (7.7 million), diabetic retinopathy ( 3.9 million). )(1). The main condition causing myopia is presbyopia (826 million)(2).

In terms of regional differences, the prevalence of distance vision impairment is estimated to be four times higher in low- and middle-income regions than in high-income regions(1). In terms of myopia, rates of unaddressed myopia are estimated to be greater than 80% in western, eastern and central sub-Saharan Africa, while similar rates are reported in the high-income regions of North America, Australasia, Western Europe and Asia Pacific. be lower than 10%(2).

Population growth and aging are expected to increase the risk that more and more people will become visually impaired.

Impact of visual impairment

Personal influence

Young children with irreversible severe visual impairment may experience delayed motor, language, emotional, social and cognitive development with lifelong consequences. School-aged children with visual impairment may also experience lower educational performance.

Visual impairments have serious consequences for the quality of life of adults. Adults with visual impairment may experience lower employment rates and higher rates of depression and anxiety.

For older adults, visual impairment can contribute to social isolation, difficulty walking, a higher risk of falls and fractures, and a greater likelihood of premature admission to nursing or nursing homes.

Economic impact

Visual impairment poses a huge global financial burden, with an estimated annual global productivity loss of approximately $411 billion at purchasing power parity(3). This figure far outweighs the estimated cost gap in meeting the unmet need for low vision (estimated at approximately $25 billion).

Strategies for treating eye diseases to prevent visual impairment

There are effective promotion, prevention, treatment and rehabilitation interventions that address the needs associated with eye diseases and visual impairment. Although many cases of vision loss are preventable (such as those resulting from infections, trauma, unsafe traditional medicine, perinatal diseases, nutritional diseases, unsafe use or self-administration of topical treatments), this is not possible for everyone. For many eye conditions, e.g. diabetic retinopathy, early detection and timely treatment are essential to prevent irreversible vision loss. Spectacle correction for refractive errors and cataract surgery are among the most cost-effective of all health interventions. Yet,only 36% of the population worldwidepeople with distance visual impairment due to refractive error have access to appropriate glasses and only 17% of people with visual impairment or blindness due to cataract have access to high-quality surgery.

Treatment is also available for many eye conditions that do not typically cause visual impairment, such as dry eye, conjunctivitis, and blepharitis, but do cause discomfort and pain. The treatment of these conditions focuses on relieving symptoms and preventing progression to more serious stages of these diseases.

Vision rehabilitation is very effective in improving the functioning of people with irreversible vision loss that can be caused by eye diseases such as diabetic retinopathy, glaucoma, the effects of trauma and age-related macular degeneration.

The WHO's response

The work of WHO is guided by the recommendations ofWHO World Report on Vision (2019)and the decision about this"integrated, people-centered eye care, including avoidable blindness and visual impairment"adopted at the 73rd World Health Assembly in 2020. The main proposal is to make integrated person-centered eye care (IPEC) the preferred care model and ensure its widespread implementation. It is expected that the report and resolution, by shaping the global vision and eye care agenda, will assist Member States and their partners in their efforts to reduce the burden of eye diseases and vision loss.

Some of the WHO's key areas of work and activities in the field of blindness prevention include:

1. Working with Member States and other partners on the ground to monitor the global goals of integrated, people-centred eye care by 2030:
   • Developerreports on the effective coverage of eye care indicators to monitor progress towards the 2030 global goals.
   • Developerresources and technical tools to support the integration of eye care into healthcare information systems.
2. Observance and promotion of World Sight Day as annual advocacy.
3. Supporting the integration of eye care into healthcare systems through the implementation of a number of technical tools:
   • OfEye care in healthcare systems: guidance for action.
   • Of Eye Care Intervention Package (PECI).
   • OfEye care competency framework (ECCF).
4. Development and implementation tools to support countries in assessing the provision of eye care services, such as:
   • The tool for analyzing the eye care situation
   • The Diabetic Retinopathy Assessment Tool and Diabetes Care Services.
   • The Glaucoma Services Assessment Tool.
   • The refractive services assessment tool.
   • The tool for rehabilitation services and systems.
5. Development of materials and resources to increase awareness about eye care:
   • OfMyopiaEd: a mobile myopia health tool to increase health literacy.
   • A population-based app for testing near and distance visual acuity.
   • Images that promote healthy eye habits.

References

1. GBD 2019 Partners for Blindness and Visual Impairment; Vision Loss Expert Group of the Global Burden of Disease Study. Causes of blindness and low vision in 2020 and 30-year trends and prevalence of avoidable blindness in relation to VISION 2020: the right to sight: an analysis for the Global Burden of Disease Study. Lancet Glob Health. February 2021; 9(2):e144-e160. doi: 10.1016/S2214-109X(20)30489-7.

2. Fricke, TR, Tahhan N, Resnikoff S, Papas E, Burnett A, Suit MH, Naduvilath T, Naidoo K, Global Prevalence of Presbyopia and Visual Impairment Due to Uncorrected Presbyopia: Systematic Review, Meta-analysis and Modeling, Ophtalmologi. May 9, 2018.

3. Burton MJ, Ramke J, Marques AP, Bourne RR, Congdon N, Jones I, et al. Lancet Global Health Commission on Global Eye Health: visie na 2020. Lancet Glob Health. 2021; 9(4):e489-e551.