This audio article is from VisualFieldTest.com.
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Excerpt:
Introduction Many people take zinc supplements believing they help the immune system or heart health. Too much zinc, however, can upset the balance of copper in the body. In rare cases, high-dose zinc over months or years causes copper deficiency, which damages the optic nerve (the bundle of fibers that carries vision signals from the eye to the brain). The result is vision loss that can look a lot like worsening glaucoma – even when eye pressure is well controlled. This article explains how zinc affects copper, how copper deficiency can hurt your optic nerve, and how that can be mistaken for glaucoma progression. We’ll highlight key clues that the problem is nutritional rather than glaucoma, and suggest safe supplement practices. At the end, a practical checklist is offered to guide doctors when a glaucoma patient’s sight falls off despite normal eye pressure. Zinc, Copper, and the Eye Zinc and copper are essential minerals needed for many body functions, including healthy vision. Both travel through your digestive system and bloodstream, but they compete for absorption. When you take a lot of zinc, it triggers production of a protein (metallothionein) in intestinal cells that grabs copper and holds it in the gut, so less copper enters your body (). In effect, excess zinc “starves” your body of copper. Over time, this can lead to low blood copper (hypocupremia). Copper is crucial for nerve health. In particular, it helps maintain the myelin sheath around nerves and is part of important enzymes. Copper deficiency can cause many neurologic problems – for example, numb hands and legs, trouble walking, and optic neuropathy (damage to the optic nerve) () (). Recognizing this is important because copper-related optic nerve damage can be treated. In fact, cases have been reported of patients who were legally blind (20/400 vision) partly regain good sight (to 20/25) after getting copper supplements (). It’s worth noting that many people regularly exceed safe zinc intakes. The National Institutes of Health advise that healthy adults only need about 8–11 mg of zinc per day, and the safe upper limit is 40 mg/day (). Yet some immune boosters, eye health formulas, and multivitamins provide 25–80 mg of zinc daily without increased copper. A survey found about 5–8% of U.S. adults taking zinc supplements exceed that 40 mg limit (). Without extra copper, long-term high zinc use can therefore create copper deficiency – so doctors should be aware of this hidden risk () (). Copper Deficiency Optic Neuropathy: Symptoms and Signs When the optic nerve is damaged by copper deficiency, vision loss usually comes on slowly and in both eyes at once. Patients often note that colors look faded and that there is a dark spot or patch in their center of vision (). One review explains that nutritional optic neuropathies typically cause a central (cee-cocentral) scotoma – a blind spot that affects the central field, with the far side vision remaining mostly fine (). In other words, side vision tends to be preserved while central sight (reading, recognizing faces) is hurt. Because both eyes are affected similarly, there usually is no relative afferent pupillary defect (RAPD) – the doctors’ test where shining light into one dark ey
