The global crisis of visual impairment: an emerging global health priority requiring urgent action

Introduction

In 2010, the World Health Organisation (WHO) reported 733 million people with visual impairment (VI) world-wide and predicted an increase to 929 million by 2020 [1]. Their updated report from late 2019 revealed a massive 2.2 billion people with VI or blindness, far exceeding their prior expectation [2]. In 2003, the World Health Service survey conducted in 70 countries across 6 continents found that, in low- and middle-income countries (LMICs), 23–24% of adults reported visual difficulty, whereas, in high-income countries, the rate was 13%. It was also reported that 5–6% of adults in LMICs suffered from severe to extreme visual difficulty, whereas in high-income countries (HICs) the rate was 2% [3]. This uneven distribution of prevalence and burden appears secondary to insufficient access to health care and rehabilitative support services [2]. Recent results of studies in LMICs highlighted the lack of access to healthcare services, medical rehabilitation (e.g., vision rehab) and assistive devices [4–7]. The delay in needed medical evaluations and preventive care inevitably leads to increases in both correctable and uncorrectable VI with concomitant increases in the economic burden on social and medical systems. The total health care expenditure was forecasted to be $2.77 trillion in 2020, a rise from $2.30 trillion in 2010[8]. In addition, the WHO reported that the global economic impact associated with just absenteeism and productivity loss, indirect medical costs, would be $176 billion in 2020 [8].

Visual impairment (VI) engenders disability across the severity spectrum as access to spatial information is lost, impeding the ability to complete critical activities of daily living. Vision plays a crucial role in the effective capture and integration of sensory information from the surrounding environment; this complex process enables individuals to localize and recognize objects, apprehend three-dimensional relationships among objects including one’s own location relative to nearby objects (egocentric), and, on a meta-level, build spatial cognition [9]. Thus, virtually all aspects of a visually impaired individual’s life are affected. More broadly, VI leads to difficulties in performing activities of daily living, reduced mobility and social participation, resulting in diminished independence and quality of life, and an increased risk of depression. Aside from the individual’s sensory limitations, there are physical/environmental (e.g., lack of accessible infrastructure) and social factors (e.g., discrimination) that may magnify the impact of the loss of vision.

Over the past few decades, global initiatives have started to address barriers regarding engagement for persons with VI, including ways to streamline social integration; however, the data reveal that social participation is certainly not satisfactory [1,10–13]. In order to aid the scientific community in a progressive set of next steps, we elaborate in this paper on critical needs with the hope that a more comprehensive perspective will galvanize stakeholders. We review VI in the International Classification of Functioning (ICF) conceptual framework, discuss international and national regulations, delineate overarching goals, and propose potential solutions.

Framework

The International Classification of Functioning, Disability and Health (ICF) established a standardized language to describe health and its associated states, matching health actions on the same subject, helping in the decision-making for the individualized rehabilitation process [14]. Here we will use the ICF, Figure 1, as a framework to explore VI and its associated disability-related ramifications.

Figure 1. Adopted from WHO, how to use ICF? VI involves bidirectional cause and effect relations between Activity, Body Function and Structure and Participation.

Impairment: Aetiology and sequelae

Globally, the most common causes of VI are uncorrected refractive errors, cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, corneal opacities, and trachoma. The leading causes of VI vary by country: in LMICs, VI caused by cataracts is more common than in high-income countries. On the other hand, VI in high-income countries is mainly attributable to diabetic retinopathy, glaucoma, and age-related macular degeneration [15]. Regardless of aetiology, health and wellbeing are attacked by vision loss, engendering mobility losses, un- or underemployment, illness and premature mortality [16]. Once the downward comorbidity spiral begins, individuals with VI are at higher risk than the general population for secondary impairment (e.g., as a result of an accident, fall and hip fractures), chronic conditions, and mental and/or social health dysfunction, as a direct or indirect result of their primary impairment [16–21]. 74% of individuals with VI report worrying about their vision, and 50% experience irritability or frustration due to their vision [22,23]. As compared to a healthy population, the risk of clinical depression is 3-times higher, and attempted suicide is increased by 5% [24]. This leaves considerable swaths of the population poor, disenfranchised, and on the receiving end of adverse health outcomes [21,25–29].

Activity limitation

Visual impairment produces deficits in performing requisite activities of daily living (ADL) and instrumental activities of daily living (IADLs); these activities include ambulation, eating, shopping, cleaning, cooking, mobility inside and outside the home (navigation), and transportation, all critical building blocks of life. VI is associated with substantial increases in trips, falls and long-bone fractures [21,25–29]. The result is feelings of anxiety and insecurity in an unknown or busy environment during walking, that is, fear of falling; once a critical point is reached many require help or companionship to travel outside of the home; this leaves many stressed, constrained in their overall mobility and functionally limited. It is not surprising that VI is an important factor in limiting engagement in physical activity generally, and, in particular, limiting activities that require travel away from home [22,30–32]. The frequency with which a VI person leaves home varies depending on the type of walking aid deployed for assistance during navigation and training [18,32]; however, the overall rate for leaving one’s domicile is strikingly low at 10%, meaning 90% are homebound [18]. These startling facts, although true in almost every high-income country, tend to be even more severe in LMICs. Studies have highlighted the significant association of VI with decreased daily activity and, perhaps most devastatingly, barriers to inclusive higher education in Thailand [20,33–36].

Participation restriction

Although studies have shown that people with disabilities are productive at work and can perform a variety of jobs, the unemployment rate of people with disabilities is much higher both in LMICs and HICs [37–42]. Data from the U.S. Bureau of Labour Statistics suggest that only 22% of the 4 million visually impaired blind in the US are employed [43]. These statistics reveal massive inequities, especially when compared to a current population-wide U.S. unemployment rate of 4%. Employment opportunities are often restricted by employer attitudes about perceived difficulties in hiring, including challenges related to obtaining adaptive equipment and providing necessary accommodations [11,13,44,45]. Environmental difficulties limit physical access to job interviews, workplace-centered spatial structures, and even work-related social events [12,46,47]. Lack of access to transportation is also a frequent reason for a person with a disability to feel discouraged when seeking work.

New challenges arise related to increases in online social participation through communication platforms that interface with mobile and/or computer technology. Although there are substantive benefits for people with disabilities and particularly those with VI through the use of assistive technologies, this group is at the highest risk of exclusion from information access [48]. Inaccessibility of online content is therefore a significant barrier for people who have VI [49]. More specifically, access to the rapidly growing world of lifestyle in-home delivery and transportation services using apps such as Uber, Grab and Grub Hub, on smartphones is mostly limited to people with normal or correctable vision, and accessibility options are often “bolted-on” and of limited use.

Interventions and goals: a call to action

Overcoming obstacles that people with VI encounter requires interventions that either eliminate or overcome environmental and social barriers. Considering the magnitude of VI, there is a global imperative to identify, study, and address barriers, with the goal of decreasing the global burden of visual disability. These efforts must “stand on the shoulders of” previous comprehensive approaches that have been carried out by government leaders, healthcare policymakers, and healthcare professionals. Federal-level legislation such as the Rehabilitation Act of 1973 or the Americans with Disabilities Act (ADA) of 1990, are landmarks in the United States, and conventions spearheaded by stakeholders at the United Nations have aided international efforts (Table 1). A touchstone that may prove useful as an archetype for federal and international expansion was the U.S. Department of Veterans Affairs (VA) Blind Rehabilitation Service policy that was implemented in 2008 to include comprehensive rehabilitation for individuals with VI into their health care benefits. This integration included not only the related medical and rehabilitation services but also funding for cutting-edge assistive technologies. These efforts have led to increased physical and social accessibility for those living with disabilities, including VI, and serve as the bedrock for future policies and programming worldwide.

Table 1. Global concerted action. A few examples of legislation that have been carried out by government leaders, healthcare policymakers, and healthcare professionals.

Scope	Legislation	Aim
International	WHO: Vision 2020	VISION 2020 is a global initiative that aims to eliminate avoidable blindness by the year 2020
	UN: Convention on the Rights of Persons with Disabilities (CRPD)	The Convention is intended as a human rights instrument with an explicit, social development dimension. It adopts a broad categorization of persons with disabilities and reaffirms that all persons with all types of disabilities must enjoy all human rights and fundamental freedoms.
	UN: Article 26, Habilitation and Rehabilitation	States parties shall take effective and appropriate measures, including through peer support, to enable persons with disabilities to attain and maintain maximum independence, full physical, mental, social and vocational ability, and full inclusion and participation in all aspects of life.
Europe	European accessibility act	The act establishes the common requirements for member countries and companies operating within the EU to provide essential services and products to disability persons.
U.S. federal law	The Rehabilitation Act Section 501	Requires affirmative action and non-discrimination in employment by Federal agencies of the executive branch.
	The Rehabilitation Act Section 503	Requires affirmative action and prohibits employment discrimination by Federal government contractors and subcontractors.
	The Rehabilitation Act Section 504	States that “no qualified individual with a disability in the United States shall be excluded from, denied the benefits of, or be subjected to discrimination under” any program or activity that either receives Federal financial assistance or is conducted by any Executive agency or the United States Postal Service.
	The Rehabilitation Act Section 508	Section 508 establishes requirements for electronic and information technology developed, maintained, procured, or used by the Federal government→ Web Content Accessibility Guidelines (WCAG) WCAG 2.0: 2008 WCAG 2.1: 2018
	Americans with Disabilities Acts 1990	Signed a law to provide civil rights protection to people with disabilities, making discrimination on the basis of disability illegal.
	Americans with Disabilities Acts Title 3	Mandates that public accommodation must be provided to disabled persons to allow for the “full and equal enjoyment” of the related privileges, goods, services, advantages and accommodations as those provided to able-bodied persons.
	Javits-Wagner-O’Day Act	The federal government is required to “purchase certain goods and services from non-profit agencies that employ the blind or visually impaired”.
	Assistive Technology Act of 2004	The goal of the act is to provide AT to persons with disabilities, so they can more fully participate in education, employment, and daily activities on a level playing field with other members of their communities. Under the law, each U.S. state and territory receives a grant to fund an Assistive Technology Act Project (ATAP).
China	Law on the protection of disabled persons (China)	The China law provides political and civil rights, remove barriers and provide rehabilitation services.
England	The Equality Act 2010 in England, Wales and Scotland	The Equality Act protects you from different kinds of discrimination. These apply in a range of different situations and include: Direct discrimination Failure to make a reasonable adjustment Victimizations
Philippines	RA 3562 – An act to promote the education of the blind in the Philippines	Under the supervision and control of the Director of Public Schools a Teacher-Training Centre to train teachers for the blind. The Philippine Normal College shall provide room and other facilities for the said Centre.

In addition to eco-systematic interventions, personal- and individual-level interventions should be emphasized and layered into a broader agenda. Primary (preventive measures) and secondary (diagnosis and treatment) prevention policies and programs have been implanted to reduce the prevalence of avoidable causes of VI, but prevalence continues to grow [50]. As the number of people with irreversible visual impairment increases, it is crucial to expand rehabilitation interventions (tertiary prevention: disability limitation) [51]. Rehabilitation has been shown to be beneficial in 75% of people with disabilities [6], with dramatic effects on quality of life [52–54].

Rehabilitation, and in particular, rehabilitation coupled with assistive technologies (AT), has the potential to empower individuals by improving functional ability and capacity. In the United States of America, data over 15 years from the National Long-Term Care Survey found that increasing the use of technology was associated with a decreased report of disability among people aged 65 years and older [55]. Another study from the United States showed that users of ATs such as mobility aids and equipment for personal care reported less need for support services.

AT It can be defined as any item, equipment or product (e.g., low vision devices, hearing aids, augmentative and alternative communication devices, and computer vision technologies) that sustain or increase the functional capabilities of individuals with a disability [56]. The goal of AT should be to increase the activity and participation opportunities for individuals with impairments and to break down pre-existing and to-be-encountered barriers.

More specifically for blind and visually impaired end users, AT has long been part of the rehabilitation process (mobility canes, optical magnifiers, Braille). As technologies expand, more sophisticated devices are becoming available to assist with ADLs and IADLs, including electronic aids such as eyeglass-mounted devices with optical character recognition (OCR) coupled with text-to-speech output, and distance and ranging sensor-based or computer vision-based systems (e.g., headset “wearable” platforms or “smart” cane “add-ons” for indoor navigation [57]). Many of these tools can be broadly categorized as (1) infrastructure-based assistive technology [IB-AT], for example, accessible pedestrian signals at intersections for road crossing assistance, and (2) infrastructure-free assistive technology [IF-AT], for example, advanced wearables that independently provide function without leveraging environmental assets. Although the value of IB is clearly palpable, these platforms are complicated and expensive to deploy at scale and to maintain with standards when the scale is factored in. On the other hand, IF-AT has the potential to perform “out of the box” and remain unwed from infrastructure. IF-AT has the potential to overcome the gap between what individuals want to do and what current infrastructure allows them to do. This being said, “plugging” wearables into existing infrastructure [IF/B-AT], a hybrid approach (Table 2), would limit the scope and scale of infrastructural assets and advanced the capabilities of the IF-AT systems in high-need locations.

Table 2. Moving forward.

Barriers	Intervention	Future
Eco-systemic and pragmatic
Inadequate policies and standards	Vision 2020 Article 26 CRPD WHO Global Strategy for Health for all	Review and revise legislation and policies
The low priority accorded to rehabilitation
Lack of provision: deficiencies in services such as health care and rehabilitation
Rehabilitation at personal/environmental levels
Lack of accessibility	WCAG Assistive technologies	Adopt national accessibility standards and ensure compliance in new buildings, in transport, and in information and communication Infrastructure-based AT Infrastructure-free AT
A lack of enforceable access standards in physical environments

In general, IF-AT wearables have advanced immensely based on innovations from the driverless car space and the integration of multiple, miniaturized electronic sensors, such as stereoscopic-vision systems and proximity-detection platforms [58]. These components can be seamlessly integrated into wearables that feature both haptic and audio outputs (human-machine interfaces), such as bone conduction headsets with synthetic speech outputs or vibrating belts or bracelets, such as the VIS⁴ION system (Visually Impaired Smart Service System for Spatial Intelligence and Onboard Navigation). This platform provides real-time situational and obstacle awareness in one’s immediate environment, allowing individuals to travel more safely in three-dimensional (3D) space and pays particular attention to low-body, mid-body, and high-body/head hazards [59–62].

Accessibility and affordability towards the united nations sustainable development goals (SDGs)

An ability to acquire and use IF-AT or IF/B-AT in the daily life of impaired persons at an affordable price shall be the deployment goal of this call to action, in direct response to two of the UNs SDGs for Good Health and Well-Being and Sustainable Cities and Communities. Affordable and ubiquitous computing within a connected world is what unlocks the potential of this goal and the tremendous advances in telecommunication technology (4G, 5G) validates the planning.

The potential is intense for state-of-the-art IF-AT technologies, not only as alternative solutions but also as ultimate solutions that can address present and future barriers on the path to total societal integration and complete enablement for persons with visual disability. Despite the fact that major problems abound within the universe of disability and the diversity of constraints that individuals face seems limitless, the expansion of IF-AT focussed on tailored capabilities will speed up the delivery of on-demand function to individuals in-need within efficient and deployable models that are modular and built for global use with universal design. Once fully envisioned, powerful and connected wearables will ensure that visually impaired persons are independent and productive citizens of the world.

Future

Now it is time that policymakers and stakeholders examine the success rate of prevailing legislation and programmatic policy and review and revise, in order to recognize gaps and barriers and to overcome them accordingly. Globalizing the VA Blind Rehabilitation Service model that encompasses an array of rehabilitative services and provides state-of-the-art assistive technology services should be fashioned into international policy and considered for implementation at the UN. National and international accessibility standards should be adapted to ensure new buildings, public spaces, transportation, and information delivery are accessible for people with disabilities across the age span and without geographic constraints. Collaborative efforts should be taken to couple and interlink the latest IF-AT with IB-AT in order to fulfil the goal of building enabling environments to empower individuals living with visual disability and beyond and remove the barriers that prevent them from engaging in the community, including accelerated gainful employment and adaptive infrastructure at the government level. At the eco-systemic level, international and national legislation should be evaluated and revised for more cross-pollination and inter-operability. At a personal level, special attention should be given to rehabilitation, and to AT, serving as an operational intervention to implement these advances. We propose strengthening and expanding IF-AT or IF/B-AT, which has the potential to empower the visually disabled to pursue opportunities that would be experienced in independent life, working, attending school, and accessing health care. We believe interventions and strategies for improving life opportunities across the ICF framework for persons with visual impairment should be prioritized. Given the time constraints, it is important that stakeholders, policymakers and health professionals take immediate action, the centrepiece of which should be the promotion of independent living at the earliest possible stage.

Consent for publication

The manuscript was reviewed and approved by all authors.

Disclosure statement

No potential conflict of interest was reported by the author(s).