Glaucoma is the leading cause of irreversible blindness worldwide 1). As of 2020, the global number of glaucoma patients was estimated at 76 million, and is projected to increase to 111 million by 2040 3). This increase disproportionately affects countries in Africa and Asia 3).
Compared to developed countries, patients in developing countries have higher incidence rates, are often already at an advanced stage at the time of diagnosis, and have a higher risk of blindness. The asymptomatic progression of glaucoma leads to significant diagnostic delays in regions with inadequate screening systems.
Even in European population-based studies, at least 50% of glaucoma cases are undiagnosed, and even higher undiagnosed rates have been reported in Asia and Africa 2). In countries with aging populations, the number of glaucoma patients is expected to increase substantially, making efficient resource use, improved healthcare access, and increased disease awareness essential 1).
In developing countries, ophthalmologists are concentrated in urban areas, preventing rural residents from receiving regular eye exams. Glaucoma progresses asymptomatically, leading to severe diagnostic delays; a study in Ghana found that 34% of patients were bilaterally blind at the time of initial diagnosis. Additionally, high drug costs and inadequate follow-up systems make it difficult to continue treatment.
| Category | Region | Prevalence |
|---|---|---|
| Primary open-angle glaucoma | Africa | 4.20% |
| Primary open-angle glaucoma | Latin America | 3.65% |
| Primary open-angle glaucoma | Asia | 2.31% |
Primary open-angle glaucoma is the most common type worldwide, with the highest prevalence in African-descended populations. In African Americans, the prevalence is reported to be about three times that of non-Hispanic whites, and it is also a leading cause of blindness 3). Even higher prevalence is observed in Afro-Caribbean populations 3).
Primary Open-Angle Glaucoma (POAG)
Most common type worldwide: The estimated prevalence in ages 40–80 is 3.5% for all open-angle glaucoma and 0.50% for angle-closure glaucoma 2).
African-descended populations: The highest prevalence, with reports approaching 15% in West Africans over age 80.
Genetic background: Polygenic and multifactorial inheritance; associations with specific genes remain largely unidentified.
Primary Angle-Closure Glaucoma (PACG)
About half of glaucoma-related blindness: Although less common than primary open-angle glaucoma, it accounts for about half of glaucoma-related blindness worldwide.
Concentrated in Asia: In Myanmar, the prevalence reaches 2.5%. It is more common in women, with a male-to-female ratio of 1:1.5 in Asia.
Family history risk: A study in Iran found that 58% of siblings of patients had some degree of angle closure.
About three-quarters of blind children worldwide are concentrated in impoverished regions of Africa and Asia. Primary congenital glaucoma occurs in 1 in 10,000 to 18,000 births. In populations where consanguineous marriage is common, the prevalence of primary congenital glaucoma is significantly higher.
A study in Ethiopia found that the average age at diagnosis of primary congenital glaucoma was 3.3 years, significantly later than in developed countries (within the first year of life). Glaucoma after cataract surgery is also an important type of childhood glaucoma in developing countries, with a reported risk of 6.5% at 3 years post-surgery.
Lens-induced glaucoma is the most common secondary glaucoma in resource-limited countries, reflecting the accumulation of untreated advanced cataracts. Pseudoexfoliation glaucoma is found in 35% of glaucoma patients at one clinic in Ethiopia.
Barriers to Diagnosis
Delayed diagnosis: A study in Ghana found that at initial diagnosis, 34% had bilateral blindness and 50% had unilateral blindness. In sub-Saharan Africa, the rate of unilateral blindness reaches up to 56%.
Lack of equipment: In Nigeria, 15–20% of clinics lack basic diagnostic equipment. Visual field testing and OCT are unavailable in many facilities.
Workforce shortage: Ophthalmologists are concentrated in urban areas, making even gonioscopy difficult in rural areas. The van Herick method or oblique illumination is often used as a substitute.
Barriers to Treatment
Medication costs: A study in India found that the monthly cost of glaucoma medications ranged from 13% to 123% of the monthly income of the lowest income group. Travel costs often exceed medication costs.
Adherence: In sub-Saharan Africa, medication compliance is low, ranging from 32.5% to 65.4%.
Acceptance of surgery: Due to lack of disease understanding, acceptance rates for glaucoma surgery are low. Unlike cataract surgery, the inability to expect vision recovery is a barrier.
Follow-up: Long-term follow-up is difficult due to economic and geographic barriers.
Psychosocial impacts are also severe. A study in India found that the mean QOL utility value for glaucoma patients was 0.64, significantly lower than that of glaucoma patients in the United States. Increased prevalence of depression has been reported among caregivers of blind patients, reaching 48% for caregivers of patients with no light perception. Blindness results in the loss of labor for both the patient and the caregiver, affecting the local economy.
The main reasons are high drug costs (13–123% of monthly income for the lowest income group), limited access to pharmacies, variability in the quality of generic drugs, and difficulty in follow-up. Therefore, drug therapy is often limited to patients with early glaucoma who are likely to adhere, or to patients who refuse surgery.
In developing countries, trabeculectomy (with antimetabolites) is positioned as the first-line treatment for glaucoma. It can be performed with minimal equipment, does not require implantation of expensive devices, and can eliminate the need for long-term drug therapy, making it the most cost-effective glaucoma surgery.
Drug therapy is usually limited to the following cases:
In suburban and rural areas of developing countries, delayed presentation and high intraocular pressure may result in poor response to conventional drug therapy 4). The Asia-Pacific Glaucoma Society (APGS) and AAPPO expert panel recommend argon laser peripheral iridoplasty (ALPI), anterior chamber paracentesis (ACP), and laser peripheral iridotomy (LPP) as alternative treatments for rapid intraocular pressure control in low-resource settings 4).
Medical therapy is costly (13–123% of monthly income), with difficulties in regular drug procurement and follow-up, and low medication adherence. Trabeculectomy can be performed with minimal equipment, does not require expensive devices, and can eliminate the need for long-term medication, making it the most cost-effective option. Additionally, many cases are advanced at the time of presentation, making early surgical intervention essential for preserving visual function.
In low- and middle-income countries, large-scale screening is difficult due to time, transportation, and cost constraints, but advances in AI are becoming a new tool for ophthalmic disease screening. AI technology has the potential to address unequal distribution of medical resources and reduce the burden of patient travel 5).
Technologies enabling remote consultation and monitoring may alleviate the shortage of ophthalmologists. If home-based visual acuity and visual field assessments using mobile applications become more refined, significant progress in home monitoring is expected 1).
Advances in research on ocular and systemic risk factors may significantly improve individual risk stratification in the future 1). The development of screening programs that efficiently allocate medical resources to the highest-risk populations is also anticipated 1).
