|The likelihood of developing glaucoma skyrockets once myopic patients have a refractive error worse than -6D. Photo: Sarah B. Klein, OD. Click image to enlarge.|
While it is known that myopia is a proven risk factor for open-angle glaucoma (OAG), there remains a research gap regarding the association between the degree of myopia and increased risk of OAG. This recent meta-analysis of over half a million individuals concluded that not only does glaucoma risk increase by 20% for each 1D increase in myopia, but also that those with high myopia face an even greater risk.
Researchers gathered data from 24 population-based studies in 11 countries, totaling 514,265 individuals, through November 2020 that reported on both myopia and OAG. They found that every degree of myopia from low to high was associated with an increased risk of glaucoma in a dose-response manner.
The pooled odds ratio (OR) of the association of myopia degree with OAG was 1.88. Ethnicity and geographic location were not linked to significant OR differences in the study sample. The pooled ORs of the associations between myopia and OAG varied across the different myopia degrees as follows: low, 1.5; moderate, 1.69; moderate-to-high, 2.27; high, 4.14. This risk was further accelerated at -6D and even further from -8D onward, revealing that the relationship between myopia and OAG risk is a concave upward slope.
“We found that the odds of developing OAG increased gradually from 1.5 to 4.14 with the increase of the degree of myopia from low to high,” the researchers wrote in their study. “This pronounced dose-response relationship seems to suggest a possible explanation for the pathogenesis of glaucomatous damage in eyes with myopia. Because of myopic eyes’ elongated axial length and thinner sclera, the optic nerve head has been presumed to be more vulnerable to the damage typically incurred in glaucoma.”
This study demonstrated a significant risk for glaucoma in every myopia category, especially for those with refractive errors worse than -6D. Consider monitoring this group of patients more vigilantly to watch for signs of glaucoma.
Ha A, Kim CY, Shim SR, et al. Degree of myopia and glaucoma risk: a dose-response meta-analysis. Am J Ophthalmol. October 6, 2021. [Epub ahead of print].