Glaucoma Risk Rises 20% For Each Diopter Change in Myopia

According to the results of a recent meta-analysis published in the American Journal of Ophthalmology, for each unit increase in myopia, the risk of glaucoma increases by approximately 20% and increases even more in high-degree myopia. 

The investigators conducted a dose-response meta-analysis to verify the relationship between degree of myopia and open-angle glaucoma (OAG) risk.

They systematically searched the PubMed, EMBASE and Cochrane Library databases to identify relevant population-based studies on both myopia and OAG published until November 30, 2020. The team used a variety of statistical analyses to examine the association between the 2 conditions and to calculate the OAG risk per unit dose of myopia (spherical equivalent [SE] decrease of 1 diopter [D]).

The investigators identified 24 studies that took place in 11 countries, yielding a total study population of 514,265 individuals. The pooled odds ratio (OR) for the association between any degree of myopia and OAG was 1.88 (95% confidence interval [CI], 1.66–2.13; I²=53%). When the team conducted subgroup analyses based on ethnicity (Asians vs. Westerners) and geographic area, no significant differences in ORs were observed (P =.80 and P =.06, respectively). 

When the team analyzed the data according to the degree of myopia, the pooled ORs for the association with OAG were 1.50 (95% CI, 1.29–1.76) for low, 1.69 (1.33–2.15) for moderate, 2.27 (1.74–2.96) for moderate-to-high, and 4.14 (2.57–6.69) for high myopia. They also demonstrated for every SE 1 D change, the pooled OR was 1.21 (95% CI, 1.15-1.28), and the OAG risk increased at approximately -6.00 D and further increased at –8.00 D,  resulting in a nonlinear, concave, upward slope (P =.03).

Limitations of the study included heterogeneity in OAG-diagnostic criteria and the handling of covariates across studies, the inability of refractive error to differentiate among axial, corneal, and lenticular refractive components, and other challenges related to the morphologic characteristics and structural changes in myopic eyes.

“This systematic review and meta-analysis affords the most updated and most comprehensive summary estimates of the dose-response relationship between myopia and OAG risk,” according to the researchers. “There should be increased awareness of glaucoma among individuals with myopia, regardless of its degree. Importantly, more vigilant monitoring is needed in myopia worse than -6.00 D, given the steeply increasing risk incurred in high-degree myopia.”

Reference

Ha A, Kim CY, Shim SR, Chang IB, Kim YK. Degree of myopia and glaucoma risk: a dose-response meta-analysis.  Am J Ophthalmol. 2021;S0002-9394(21)00523-7. doi:10.1016/j.ajo.2021.10.007