Eyeworld

EW GLAUCOMA 52 July 2018 Dr. Demer hopes that practi- tioners come away from the study with the realization that this is a plausible theory about normal ten- sion open angle glaucoma. "If this theory is sufficiently supported to motivate change in clinical practice, it could dramatically alter the way glaucoma is diagnosed and treated for a large number of patients," he said. "Also, this may have impli- cations for an even bigger disease, which is the worldwide epidemic of myopia." EW Reference 1. Demer JL, et al. Magnetic resonance im- aging of optic nerve traction during adduction in primary open-angle glaucoma with normal intraocular pressure. Invest Ophthalmol Vis Sci. 2017;58:4114–4125. Editors' note: Dr. Demer has no finan- cial interests related to his comments. Contact information Demer: jld@jsei.ucla.edu said. "Our theory also proposes this is where the damage occurs because our calculations suggest from the computer model that this is where the damage will be." The impact that such repetitive movements have on the eye should not be underestimated. "We think that this may be a major cause of visual loss in glaucoma," Dr. Demer said, adding that it may also be a factor in myopia. The force concen- tration on the back of the eye seems to be occurring in an area where the eye gets elongated in myopia. "All of the forces that we calculate to be exerted by the optic nerve on the back of the eye match the distribu- tion of eyeball stretching that occurs in nearsightedness," he said. This is particularly true for severe axial myopia, he stressed. Clinical strategies In the case of glaucoma, if such repetitive eye movements prove to be pivotal, there are several clinical strategies that could be easily imple- mented. "If this proves to be true, reducing the angle of adduction and/or the force of the medial rectus muscle that's causing the adduction would reduce the force exerted by the optic nerve against this very sus- ceptible junction with the eyeball," Dr. Demer said. One way to do this would be with eye muscle surgery to weaken the range of the adduction eye movement. Another possibility would be to increase the relative length of the optic nerve so that there is greater slack here. To do that, physicians could perform orbital decompres- sion surgery, drilling out some of the wall of the orbit, to make the eye sink back into the socket. Or they could use liposuction to remove some of the fat in the eye socket to accomplish this. Yet another possi- bility might be to use a medication to cause atrophy of some of this fat, such as a prostaglandin analog drug, Dr. Demer said. Normal continued from page 51 " If this proves to be true, reducing the angle of adduction and/or the force of the medial rectus muscle that's causing the adduction would reduce the force exerted by the optic nerve against this very susceptible junction with the eyeball. " —Joseph Demer, MD

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