Eyes with high myopia have a 7.3 fold increased risk of developing open-angle glaucoma (OAG) compared to emmetropic eyes, according to 10-year analysis of data from a population-based Beijing Eye Study of 4,439 adults.
This 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.
“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,” Dr Ya Xing Wang reported to the virtual Association for Research in Vision and Ophthalmology meeting. “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.”
The incidence 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 cupto- 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 millimetre of increase in axial length, it increased by a factor of 1.7. Eyes with axial length of 26mm or more had a five-fold increased risk for developing glaucoma. Eyes with a thinner cornea were also found to have a higher chance of incident OAG.