Relationship of Lifestyle, Exercise, and Nutrition With Glaucoma

Claudio I. Perez; Kuldev Singh; Shan Lin

Disclosures

Curr Opin Ophthalmol. 2019;30(2):82-88. 

In This Article

Smoking

Many active compounds found in tobacco smoke are toxic to ocular tissues, affecting the eye through ischemic or oxidative mechanisms.[4] Nevertheless, the relationship between smoking and glaucoma risk has not been well elucidated. Some large well-designed studies, such as the Beaver Dam Eye Study,[5] the Proyecto VER,[6] the Los Angeles Latino Eye Study,[7] and the Rotterdam Study,[8] have failed to show a relationship between glaucoma and cigarette consumption. However, a recent study done in a large sample population from the US National Health and Nutrition Examination Survey found that among smokers, heavy smoking defined by greater number of packs of cigarettes smoked per day was associated with higher odds of glaucoma (odds ratio 1.7).[9] A recent case-control study done among Asian study participants, reported a protective effect of smoking for patients with normal tension glaucoma, nevertheless the association was no longer significant when controlled for income.[10] Two prospective studies had evaluated the effect of smoking on glaucoma incidence. First, a large prospective study among health professionals throughout the United States, which assessed cigarette smoking exposure repeatedly over a decade, found that cigarette smoking did not increase the risk of developing POAG.[11] Second, a large prospective study among a Spanish cohort of university graduates found that smokers had an increased risk of developing glaucoma after 8.5 years of follow-up.[12] Furthermore, the authors found a dose–response relationship among smokers, with the highest quintile having a higher risk than the first quintile.[12] Another prospective study showed that among patients with POAG, smokers developed more paracentral defects in comparison with nonsmokers.[13] Recently, among patients with angle closure disease, smoking was an independent risk factor for intraocular pressure (IOP) fluctuation, which may be explained by the reduced aqueous outflow resulting from vasoconstriction of episcleral veins.[14] Nevertheless, in a secondary analysis of data from a randomized control trial, smoking was not associated with mean, peak, or variability of IOP in a nonglaucomatous population.[15] Finally, one study suggests that smoking could be an independent risk factor for progression in the inferior visual field sector.[16] This may reflect the effects of ischemia because of smoking given that nonarteritic anterior ischemic optic neuritis can also cause similar inferior altitudinal defects.[17] Nevertheless, the reason why smoking was not a risk factor for progression in the superior hemifield remains unclear.

The discrepancies among studies on the association between smoking and glaucoma may be partly because of the complexity of the relationship. Smoking has been demonstrated, through many possible mechanisms, to be detrimental to ocular tissues and it has been postulated to be harmful with regards to glaucoma, via mechanisms such as alteration in ocular perfusion,[18] the generation of free radicals and decrease in the levels of antioxidants in the blood circulation, aqueous humor, and ocular tissue.[19] Inflammation and apoptotic marker levels in aqueous humor and plasma were found to be increased in smokers with glaucoma as well.[20] Despite the adverse effects of smoking or nicotine use on ocular circulation and tissues, protective mechanisms of nicotine on the optic nerve circulation have also been proposed. Nicotine may induce the liberation of nitric oxide from perivascular nitrergic neurons, resulting in vasodilatation.[21] Although the relationship between smoking and glaucoma is not conclusive, the preponderance of evidence showing the negative impact of smoking on overall health should lead practitioners to advise patients to stop smoking, knowing that advice related specifically to glaucoma will not be based on strong evidence.

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