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Editors Selection IGR 20-4
Epidemiology: Have prevalence and incidence of glaucoma changed in a decade?
Comment by Catherine Jui-Ling Liu on:
67610 The Prevalence and the Incidence of Diagnosed Open-Angle Glaucoma and Diagnosed Angle-Closure Glaucoma: Changes From 2001 to 2010, Chiu SL; Chu CL; Muo CH et al., Journal of Glaucoma, 2016; 25: e514-e519
Primary angle-closure glaucoma (ACG) is more visually destructive than open-angle glaucoma (OAG), and its prevalence increases exponentially with age.1,2 Using the National Longitudinal Health Insurance Database, the authors analyzed the incidence and prevalence of OAG and ACG in one million subjects from year 2001 to 2010. They found the prevalence of both types of glaucoma increased over the years, but OAG showed a steeper trend than ACG, making it more prevalent after the year 2005. As well, there was a significantly decreasing trend in ACG incidence over the years; more significant in woman than in men. The authors attributed these findings to the high prevalence of myopia and increasing number of cataract surgery in Taiwan.
The findings may not be surprising in a society where myopia is prevalent and healthcare is accessible and inexpensive, but cautions should be exercised before we draw conclusions. Population studies found most OAG patients are unaware of this disease before study examinations,3 and ACG also may be under-diagnosed because most cases are asymptomatic until late stage.2 In this study, ACG might be underestimated to a greater extent than OAG because ACG is more prevalent in subjects with low socioeconomic status which is a barrier to healthcare access.4,5 Another study limitation is uncertainty about accuracy of the diagnosis coding. Sometimes it is challenging to discriminate glaucomatous damage from myopic changes. Under such circumferences, physicians may opt for coding related to OAG, resulting in overestimation of its prevalence and incidence in populations prevalent with myopia.
ACG might be underestimated to a greater extent than OAG because ACG is more prevalent in subjects with low socioeconomic status which is a barrier to healthcare access
The fact that the authors used loose criteria for case selection may increase this possibility. Despite these limitations, the study results may reflect the reality that echo findings from another study which showed the incidence of primary ACG appeared to be decreasing after reaching a peak in the late 1990s.6
References
- Quigley HA, Broman AT. The number of people with glaucoma worldwide in 2010 and 2020. Br J Ophthalmol 2006;90:262-267.
- Foster PJ, Oen FTS, Machin DM, et al. The prevalence of glaucoma in Chinese residents of Singapore. Arch Ophthalmol 2000;118:1105-1111.
- Tielsch JM, Sommer A, Katz J, et al. Racial variations in the prevalence of primary open angle glaucoma: the Baltimore Eye Survey. JAMA 1991;266:369-374.
- Yip JL. Nolan WP, Davaatseren U, et al. Primary angle closure glaucoma in East Asia: educational attainment as a protective factor. Ophthalmic Epidemiol 2011;18:217-225.
- Ko YC, Hwang DK, Chen WT, et al. Impact of socioeconomic status on the diagnosis of primary open-angle glaucoma and primary angle closure glaucoma: a nationwide population-based study in Taiwan. PLoS One 2016; Feb 23, 0149698.
- Keenan TDL, Salmon JF, Yeates D, et al. Trends in rates of primary angle closure glaucoma and cataract surgery in England from 1968 to 2004. J Glaucoma 2009;18:201-205.
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