IOP and lifestyle

Recent research shows that following maternal guidance such as eating vegetables, regular exercise and maintaining healthy body weight reduce the risk of developing open-angle glaucoma in patients with high intraocular pressure (IOP), Cynthia Mattox MD, of New England Eye Center, Tufts University, Boston, USA , told the 2016 American Academy of Ophthalmology Annual Meeting in Chicago, USA. Higher consumption of dark green, leafy vegetables and other dietary sources of nitrates can lower glaucoma risk by 30% overall and as much as 50% in patients prone to paracentral visual field loss, Dr Mattox said. Nitrates and nitrites are precursors of nitric oxide, which plays an important role in aqueous outflow signalling and has emerged as a therapeutic target for regulating IOP. (Kang JH et al. JAMA Ophthalmol. 2016;134(3):294-303.) Higher intake of fresh oranges and peaches, and collard greens and kale, is associated with lower glaucoma rates among older African-American women (Giaconi JA et al. Am J Ophthalmol 2012;154(4):635-644). A similar diet is associated with less glaucoma in older women (Am J Ophthalmol 2008;145(6):1081-1089), as is intake of retinol equivalents and beta-carotene. (Ramdas WD et al. Eur J Epidemiol. 2012 May; 27(5): 385–393.) Commencing regular aerobic exercise can lower IOP and glaucoma risk in previously sedentary patients (Passo MS et al. Arch Ophthalmol. 1991 Aug;109(8):1096-8), and may increase when regular exercise ceases, Dr Mattox noted. However, isometrics, heavy weight lifting and prolonged Valsalva forced exhalation are associated with increased IOP, as are inversion manoeuvres on tilt tables or back swings. Encouraging healthy body weight also helps reduce IOP. However, low body mass index is associated with paracentral visual field defects. Mineral supplements generally are not beneficial, and high doses of iron and calcium can increase glaucoma risk (NHANES 2015), as can magnesium (Passo MS et al. Arch Ophthalmol. 1991 Aug;109(8):1096-8). Generally, supplements should be avoided in the absence of nutrient deficit, Dr Mattox said. Some evidence exists for the beneficial effects of herbal antioxidants, such as allium, bilberry, wolfberry, crocetin in saffron, gardenia fruit and resveratrol, Dr Mattox said. Astragalus, foeniculeum and brown algae seaweed have been shown to reduce IOP in animal models. Sleep position also influences IOP. In patients with a preferred sleeping side, IOP is higher on the side on which they habitually sleep, Dr Mattox said. Alternating sides or using a head-up wedge pillow mitigates supine IOP elevation (Buys YM et al. Ophthalmology. July 2010;117(7):1348-1351). Overtreatment of hypertension and nocturnal anti-hypertensive dosing also should be avoided, she advised. Cynthia Mattox: cmattox@tuftsmedicalcenter.org