by Allen Casey
(Editor’s Note: Allen Casey is a retired educator and CEO, a former Fulbright Fellow to India and England and a member of the ACB International Relations Committee.)
Blindness manifests no respect for people, places or politics. It robs one of sight, opportunity and hope. It reaches around the globe into every nation and touches millions of lives. It challenges the best scientific minds and medical skills to develop technology, treatments and cures. Its root causes may be as simple as a mosquito bite or as complex as a gene gone awry. No one is immune from its grip on life. According to “The Lancet,” a U.K. publication embracing several medical and scientific journals, blindness globally is particularly detrimental to an estimated 31 million people over the age of 50. Its presence in and impact on other population groups — adults and children — is no less ominous. Understanding the global reach of blindness is made more difficult by the inconsistency in numbers of affected people in respective countries and the compilation of data internationally. The principal resources employed in the preparation of this report are the CDC, USAID, National Institutes of Health (NIH), World Health Organization (WHO), International Agency for the Prevention of Blindness (IAPB), National Organization for Rare Disorders (NORD) and “The Lancet.”
Globally the major disease-related causes of blindness are cataracts, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR) and retinitis pigmentosa (RP). Lesser causes are river blindness (filariasis and trachoma), albinism, childhood diseases and vitamin A deficiency. Visual impairment or low vision is the principal result of uncorrected refractive error, i.e. myopia, hyperopia, presbyopia and astigmatism. However, low vision may be a precursor to total blindness.
Cataracts: According to the World Health Organization, 50 percent of vision loss globally is attributed to cataracts. Its presence is higher among women than men and among African Americans. The principal contributing factors are aging, trauma, diabetes, exposure to UV lighting, smoking and genetics. It also is believed to be linked to economic status. Cataracts are most prevalent globally in East Asia, tropical Latin America, Western Europe and sub-Saharan Africa.
Glaucoma: Glaucoma, the World Health Organization reports, is the second leading cause of blindness worldwide, affecting an estimated 80 million people by 2020. It often is characterized as the “silent thief,” as damage to the optic nerve often goes undetected until visual acuity is permanently compromised. Glaucoma is most prevalent among populations of Africa and Asia.
Age-related Macular Degeneration (AMD): As the name implies, age-related macular degeneration is directly related to age. It is the third leading cause of blindness globally as well as in economically advanced countries. The European Blind Union estimates that AMD accounts for 90 percent of blindness among those age 65 and older. Other contributing factors are tobacco smoking and genetics.
Diabetic Retinopathy (DR): As one of the leading causes of blindness globally, diabetic retinopathy is indicative of specific lifestyles, namely low economic status, poor control of blood sugar, high blood pressure and obesity. An estimated 140 million people have DR. It is common to the Eastern Mediterranean, Western Pacific, Southeast Asia and some parts of Africa.
Retinitis Pigmentosa (RP): According to the National Eye Institute, retinitis pigmentosa is the result of a rare genetic disorder that typically causes a gradual decline in visual acuity accompanied by a narrowing of the visual field until only light perception remains. RP affects an estimated 26 million people globally, with a significant number in the United States.
River Blindness: As the name suggests, river blindness is associated with life along rivers in South America, Central America, South Asia and Southeast Asia. These infections arise from mosquito and black fly bites transmitting the filariasis parasite. The optic nerve and cornea most often are compromised. An estimated 25 million people are infected. Trachoma is one of the oldest known infectious diseases leading to blindness. It affects approximately two million people in 44 countries.
Albinism: Albinism is the result of a rare genetic mutation that not only causes visual impairment and total blindness but also leaves the individual with noticeable dermatological anomalies and psychological stress. It is most prevalent in the Caribbean, East Africa, South Asia, China, Scandinavia and the United States.
Childhood Diseases: Childhood diseases leading to blindness (e.g., measles) generally are considered avoidable when proper precautions are taken in a timely manner. A not uncommon phenomenon contributing to childhood blindness is retinopathy of prematurity (ROP), a condition more prevalent in Asia, Eastern Europe and Russia. A second adverse element is failure to practice good dental hygiene. It is estimated that at least 50 percent of blindness in children is attributed to ROP. The World Health Organization considers ROP a major global concern.
So, what does the future hold for global blindness? Projections in “The Lancet” suggest that by the year 2050 the number of blind and visually impaired will triple, increasing to 115 million blind and 588 million visually impaired. It is of little comfort that we are not now and will not be alone in the future world of blindness and visual impairment. These projections only intensify the challenges we face as global citizens.