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Open-angle glaucoma, ocular hypertension associated with myopia
In a study recently published in Ophthalmology, researchers reported that hyperopia was associated with an increased prevalence of primary angle-closure glaucoma, and myopia was associated with an increased prevalence of open-angle glaucoma.
Shen and colleagues conducted a cross-sectional study to investigate associations between refractive error and glaucoma in a multi-ethnic population.
Researchers studied participants who were 35 years old or older, which included 34,040 participants with glaucoma or ocular hypertension (OHTN) and 403,398 control participants. The participants had no history of refractive surgery, corneal disorder or cataract surgery.
Results showed that the control group had a mean spherical equivalent of -0.59 D. Researchers reported that with each 1-D decrease in spherical equivalent, results showed a 22% decrease in the chance for primary angle-closure glaucoma. This same measurement was associated with increases in the odds for pigmentary glaucoma (PIGM), pseudoexfoliation glaucoma and ocular hypertension.
"We observed that myopia was associated with an increased prevalence of all forms of open-angle glaucoma and OHTN, whereas hyperopia was associated strongly with an increased prevalence of angle-closure glaucoma across all racial or ethnic groups," the authors stated. "The strongest association of myopia was with PIGM, normal tension glaucoma among Asians and non-Hispanic whites, and POAG. These findings argue for further investigation into the relationship of refractive errors and glaucoma using longitudinal data."
They concluded that future studies should investigate how genetic factors and biological mechanisms that underlie eye growth and the development of refractive errors potentially influence the risk of glaucoma. – by Chelsea Frajerman Pardes
Disclosure: The authors reported no relevant financial disclosures.
Perspective
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In demonstrating a “dose-response” relationship between refractive error and glaucoma, Shen and colleagues corroborate the already-established links between hyperopia and angle-closure glaucoma, and myopia and open-angle (including normal-tension and pigmentary) glaucoma.
In light of the increasing global prevalence of myopia, what can optometrists put into practice today to help optimize the care of individual patients?
We must begin by recognizing that myopia is both a risk factor for and a differential diagnosis vs. glaucoma. Biomechanical factors may predispose myopic patients to develop open-angle glaucoma (OAG): increased axial length may compromise scleral and laminar integrity, increasing retinal ganglion cell vulnerability to relatively low intraocular pressures. Myopic structural and functional abnormalities can mimic (or mask) those of glaucoma and may cause visual field defects indistinguishable at presentation from those due to glaucoma. Fortunately, in the absence of myopic (or other) maculopathy, ganglion cell analysis may provide valuable complementary information.
Ultimately, an accurate differential diagnosis hinges on the definition of glaucoma as a progressive optic neuropathy. Although myopic patients may present with structural and functional defects suggestive of OAG, establishing solid baseline data and monitoring for progression through longitudinal follow-up (comparing myopic patients to themselves, not to a potentially inappropriate reference database) is critical in determining a definitive diagnosis and treatment plan.