As cases of glaucoma are expected to climb, understanding the rate of undetected glaucoma aids in preparing public health interventions.
Africa and Asia are more likely to have undetected glaucoma compared with Europe, and countries with low human development index (HDI) have a higher proportion of undetected manifest glaucoma than countries with higher HDI, according to a systematic review and meta-analysis published in Ophthalmology.
Researchers included articles published between January 1990 and June 1, 2020 from several databases. The 61 articles they included (189,359 participants, 6,949 with manifest glaucoma) were population-based studies of specific geographical regions or populations with diagnoses based on structural and functional evidence of glaucomatous damage.
The researchers found that at least half of all glaucoma cases are undetected in every region of the world.
Africa had the highest proportion of previously undetected cases. Countries in the Oceania region had the least. Africa (odds ratio (OR) 12.70, 95% confidence interval (CI) 4.91, 32.86) and Asia (OR 3.41, 95% CI 1.63, 232 7.16) had significantly higher odds of undetected manifest glaucoma compared with Europe.
The highest proportion of previously undetected cases of primary open angle glaucoma (POAG) was found in Africa, and the least was found in North America. Africa (OR 8.84, 95% CI 2.64, 29.62) and Asia (OR 4.66, 237 95% CI 2.07, 10.51) again had significantly higher odds of undetected POAG compared with Europe.
Previously undetected cases of manifest glaucoma were significantly higher (94.56%, 95% CI 92.13, 96.27) in countries with HDI <0.55 than in countries with medium (OR 0.20, 95% CI 0.10, 0.42), high (OR 0.20, 95% CI 0.09, 0.47), or very high (OR 0.12, 95% CI 0.06, 0.24) HDI.
The proportion of previously undetected cases of POAG surpassed 90% in countries with low and medium HDI (85.97% (95% CI 73.27, 93.51). Countries with high HDI had a proportion of about 86%. The proportion for countries with very high HDI was about 73%.
Individuals in Africa and Asia had the highest proportions of previously undetected cases of manifest glaucoma (Africa: OR 5.55, 95% CI 2.41, 12.78; Asia: OR 2.62, 95% CI 1.26, 5.48) and POAG (Africa: OR 3.73, 95% CI 1.65, 8.41; Asia: OR 2.67, 95% CI 257 1.09, 6.57). Populations with mixed ancestry had the least.
Urban areas (OR 0.52, 95% CI 0.27, 0.99) had lower odds of undetected POAG than rural areas.
In a sensitivity analysis, Africa retained the highest proportion of previously undetected cases but North America, not Oceania, had the least.
Researchers said that 43.78 million people (95% CI 41.92, 45.46) in 2020 are projected to have undetected POAG, and 76.7% of them are in Asia (58.4% of cases) or Africa. Undetected POAG cases may rise 53.2%, impacting 67.06 million people (86.3% in Africa) by 2040 if the global proportion is maintained.
Limitations of the study included the failure to register review protocol before beginning the study, the variation in glaucoma diagnosis criteria among studies, patients’ possible lack of awareness of their diagnosis, and inadequate assessment of intra-region and intra-country differences.
“The need to improve glaucoma detection is palpable,” according to the researchers. They call for “a paradigm-shift from a passive opportunistic case-finding approach to a more proactive screening strategy. Although the cost of mass-screening for glaucoma has been cited as a debilitating factor, cost-effective population-based screenings have been reported in China and India.”
“The advent [of] artificial intelligence and information technologies such as the internet-of-thing have the potential to redefine the delivery of eye care services, including glaucoma detection, and should be further evaluated for use in community settings,” the researchers suggest.
Soh ZD, Yu M, Betzler BK, et al. The global extent of undetected glaucoma in adults: a systematic review and meta-analysis, Ophthalmol. Published online April 15, 2021. doi:10.1016/j.ophtha.2021.04.009