Beijing Eye Study identifies high myopia as major risk factor for developing glaucoma
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High myopia is a major risk factor for the development of open-angle glaucoma, accounting for a 7.3-fold increased risk as compared with emmetropic eyes, according to a 10-year analysis of data from the Beijing Eye Study.
“Increased probability to develop glaucoma may be due to axial elongation, including elongation and thinning of the lamina cribrosa, enlargement of Bruch’s membrane opening, and a lengthening and thinning of the peripapillary choroidal border tissue,” Ya Xing Wang, MD, said at the virtual Association for Research in Vision and Ophthalmology meeting.
The Beijing Eye Study is a population-based study conducted in the adult Chinese population of greater Beijing. A total of 4,439 participants were enrolled in 2001, and 60.7% of them were reexamined after 10 years. Flicker chronoscopy was used to evaluate structural changes in the appearance of the optic nerve head and retinal nerve fiber layer, which, together with an open anterior chamber angle on anterior segment OCT, would potentially lead to the diagnosis of open-angle glaucoma (OAG).
“Of 2,494 participants free of glaucoma at baseline, 75 developed OAG in at least one eye in 2011, with a 10-year incidence of 3%. The 10-year incidence increased with older age. It was 1.8% in participants in their 40s and 50s and increased to 5.6% and 5.9% in those over 60 and 70, respectively,” Wang said.
In myopic and especially highly myopic eyes, the incidence was significantly higher than in non-myopic eyes, she said. It was 2.1% in the emmetropia group, increasing to 6.2% in low myopia, 8% in moderate myopia and 13.3% in high myopia.
Overall, risk factors for glaucoma were older age, longer axial length, larger cup-to-disc ratio, thinner central corneal thickness (CCT) and higher IOP at baseline.
For each year of age, the risk increased by a factor of 1.06, and for each millimeter of increase in axial length, it increased by a factor of 1.7. Eyes with axial length of 26 mm or more had a fivefold increased risk for developing glaucoma.
Eyes with a thinner cornea were also found to have a higher chance of incident OAG.
“This finding is in agreement with the Early Manifest Glaucoma Trial and other investigations, although it is still unclear whether thinner CCT is a structural or a diagnostic risk factor,” Wang said.
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Wang YX, et al. 10-year incidence of open-angle glaucoma in highly myopic eyes as compared with non-highly myopic eyes in the Beijing Eye Study. Presented at: Association for Research in Vision and Ophthalmology annual meeting; May 1-7, 2021 (virtual meeting).
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