Diet, Exercise, and Overall Health

Experts commissioned by the World Health Organization (WHO) and by the Food and Agriculture Organization have noted that the key measures to combat chronic cardiovascular diseases, cancer, diabetes, and obesity include a diet low in energy-dense foods that are high in saturated fats and sugars, and abundant in fruit and vegetables, together with an active lifestyle. The burden of these chronic diseases is rapidly increasing worldwide: in 2001, chronic diseases contributed approximately 59% of the 56.5 million total reported deaths in the world and 46% of the global burden of disease.

The WHO has suggested specific ways to change nutritional intake and increase energy expenditure:

• Reduce energy-rich foods high in saturated fat and sugar
• Decrease the amount of salt in the diet
• Increase the amount of fresh fruit and vegetables in the diet
• Undertake moderate-intensity physical activity for at least an hour a day

Evidence suggests that excessive consumption of energy-rich foods can encourage weight gain, and the WHO suggests limiting consumption of saturated and trans fats, sugars, and salt, often found in snacks, processed foods, and drinks.

These WHO recommendations are based on their analyses of the best available current evidence and the collective judgment of 30 international experts.

Diet, Exercise, and Ocular Health

Increased consumption of fruits and vegetables and other foods rich in antioxidants have been linked to reduced incidence of macular degeneration and other ocular conditions. Using data from the landmark Women’s Health Initiative, researchers have demonstrated associations between diet (emphasizing the specific antioxidants lutein and zeaxanthin) and age-related nuclear cataract, as well as AMD. Individuals who consume more of these antioxidants in their diets tend to be at lower risk for ocular disease.

In addition, following a healthy diet and a program of physical exercise can reduce the incidence of systemic hypertension, which is linked to the development of retinopathy (ie, hypertensive retinopathy), and is especially important in diabetic patients already suffering from the microvascular complications of their disease.

Exercise May Benefit the Ocular System Directly

Numerous studies have shown that exercise is associated with decreased intraocular pressure (IOP), both immediately after exercise, and over extended periods in individuals who exercise regularly. The precise physiologic mechanism for the acute and long-term IOP reductions associated with exercise have not been fully elucidated, but it is widely assumed that there is more than one mechanism behind the change.

IOP is reduced as a result of both aerobic exercises including jogging, bicycling, or swimming, as well as anaerobic exercises involving short bursts of exertion followed by short periods of rest, such as weight lifting. However, isometric exercise, in which the shape of the muscles does not change (pushing against a stationary object, for example) may have a lesser effect on intraocular pressure than isotonic (dynamic) exercise.

Exercise may have additional direct benefits particularly in the elderly, potentially leading to enhanced balance, coordination, and physical strength. Physical exercise may lead to increased self-confidence, encourage participation in recreational and intrapersonal activities, and improve quality of life. Recent studies have demonstrated that regular physical activity in the elderly may improve ocular function, being associated with enhanced vestibular-ocular reflex, gaze, and posture control.

Obesity and Healthy Sight

Communicating the health risks of obesity is an important component of Healthy Sight Counseling. Maintaining a normal body weight can be helpful in decreasing the risk for developing diabetes, cardiovascular disease, arthritis, and a number of other chronic conditions with potential ocular comorbidities.

Numerous population-based and prospective studies support an association between obesity and risk of age-related cataract. In one notable prospective cohort study of over 17,000 healthy men, higher body mass index was a determinant of cataract. The leanest men had the lowest rates, consistent with experimental evidence that restriction of energy intake slows development of cataract. This association was judged to be independent of age, smoking, and diagnosed diabetes. The precise nature and strength of association between obesity and cataracts, particularly with regard to different cataract subtypes, remains unclear.

The relationship between body mass index and AMD has also been studied prospectively, and it has been demonstrated that obesity is a risk factor for visually significant AMD in men, in particular for dry AMD. (Although it should be noted that the very leanest individuals also appear to be at some increased risk.) In addition, obesity is associated with elevated IOP, although to date there are no convincing data to support a direct association between obesity and glaucomatous optic neuropathy.

Smoking and Healthy Sight in the Future

As with diet and exercise, the detrimental effects of smoking on the ocular system are not limited to the comorbidities of diabetes and cardiovascular disease. Vascular effects of smoking can affect the ocular as well as the systemic circulation, contributing to circulatory insufficiency and leading to vascular occlusive changes. In addition, smoking generates free radicals in the lens, and it reduces plasma concentrations of several antioxidants and enzymes that are important for the removal of damaged proteins from the lens. Cadmium also accumulates in the cataractous lenses of smokers. Like free radicals, cadmium may hasten cataractogenesis by affecting lens enzymes thereby weakening defense against oxidative damage.

Smoking has been directly linked to cataract and AMD. In the case of cataract, the risk appears to be greatest for heavier smokers and for those who smoke for a longer duration. And while some smoking-related damage to the lens may be reversible, smoking cessation reduces the risk of cataract by limiting total dose-related damage to the lens.

Smoking and Healthy Sight Now

Smoking can also present short-term problems affecting Healthy Sight. Tobacco smoke is an irritant and an allergen that can trigger inflammation of the conjunctiva and associated ocular allergy symptoms such as itching, tearing, and irritation.

It’s important to remember, particularly for vision care professionals who serve families, that smoking affects the smoker as well as the entire household, including spouses and children, with infants being particularly susceptible.

Smoking is associated with damage to the lipid layer of the ocular surface and that, along with air-borne irritation from tobacco smoke, may contribute to ocular surface disease. Smoking may complicate contact lens tolerance, due to air-borne irritation from tobacco smoke, tear film disequilibrium, and accentuated lens surface coating.

Lifestyle and Healthy Sight

While a healthy lifestyle concentrating on a well-balanced diet, program of regular exercise, and the avoidance of risk factors like smoking and excessive alcohol intake is important to a Healthy Life, attention also needs to be focused on a healthy visual lifestyle in order to achieve Healthy Sight. Several aspects of a healthy visual lifestyle should be considered. These include 1) adequate refractive correction; 2) light control and modulation; 3) computer vision syndrome; and 4) ocular protection.

Adequate refractive correction: Healthy Sight Counseling, in its focus on achieving good vision, begins with maximizing the quantity of vision. This implies an accurate and meticulously performed refraction, leading to an eyeglass prescription that provides the patient with the best corrected acuity. When considering visual lifestyle, special attention must be directed to early or pre-presbyopic individuals with the avoidance of over-prescribing minus in the distance correction and recognizing when a near add is required for comfortable and convenient close work. It must be recalled that myopes may experience a subtle hyperopic shift around age 40 and that hyperopes of the same age may experience an increase in their hyperopia or an early-onset presbyopia, with only slight modifications in spectacle corrections serving to improve both their distance and near acuities and helping to decrease asthenopic symptoms.

Light control and modulation: Quality of vision is one of the most important components of Healthy Sight. Excessive or misdirected light can produce photosensitivity and lead to diminished contrast and increased glare sensitivity. Such problems with contrast and glare are the source of many, if not most, visual complaints related to visual comfort and convenience. The customized eyeglass prescription includes recommendations of appropriate lens enhancements—such as fixed-tint and photochromic lenses, anti-reflective coatings, and polarizing lenses—to control and modulate light and encourage the highest quality of vision for the wearer.

Computer vision syndrome: Most individuals, from children to senior citizens, are finding computer technology an increasingly important part of their day-to-day lives, especially with ever increasing Internet use. Despite the benefits of computerization in modern life, there is a price to pay for the many hours people spend at the computer. Computer vision syndrome has a number of components, ranging from problems with glare arising from the computer screen, to eye fatigue secondary to prolonged reading and focusing, to ocular irritation related to prolonged staring and its effects on blinking and ocular surface lubrication. Recommendations for appropriate eye rest and the prescription of anti-reflective eyeglass lenses can alleviate asthenopic symptoms and enhance ocular comfort during prolonged computer sessions.

Ocular protection: Three aspects of ocular protection that can impact Healthy Sight are listed below.

• Occupational protection: Important in those jobs where, by the nature of the work itself or the work environment, the eye is placed at risk. This risk can result from direct trauma, foreign bodies, or ultraviolet light exposure. Examples would include construction workers, arc welders, and various outdoor occupations such as lifeguards, ski instructors, and fishermen.
• Sports or recreational protection: Either from impact-related trauma (especially in ball sports) or UVR exposure. Both children and adults can be at risk here and the appropriate impact-resistant eyeglass lenses, sports goggles, and UVR-absorbing lenses must be recommended.
• General UVR protection: This is protection that is required for everyone and is best provided by photochromic eyewear that offers 100% UVA and UVB protection.

Occupation and Environment and Healthy Sight are explored in greater detail in the section Healthy Sight in the Future.

The Importance of Protecting the Eyes from UVR Damage: Educating the Public

Creating and reinforcing public awareness of potential risks to Healthy Sight is a fundamental component of Healthy Sight Counseling. One key area in which vision care professionals have the opportunity to educate their patients is UVR protection.

Public awareness of the link between UVR exposure and skin cancer is generally good, but there is a relative gap in knowledge about the relationship between acute and chronic UVR exposure and ocular disease. This gap exists despite convincing laboratory and epidemiologic evidence associating UVR with such vision-threatening eye disorders as cataract, macular degeneration, and pterygium (see UVR Damage). Data from an international survey in 2008 revealed that while the majority of people worldwide are generally aware of the harmful effects of UVR on the skin, only a small minority are aware of the potential for UVR-related eye problems (Table 1).

Data from the same survey clearly demonstrated that while many people habitually cover their skin, and use sunscreen or moisturizers with UVR blockers during outdoor activities, the majority do not similarly protect their eyes (Table 2).

Ocular UVR protection should be an important component of the preventive medicine aspect of HSC and educational and public outreach efforts in this regard are crucial elements of advocacy to promote Healthy Sight.

Environment and Healthy Sight

When it comes to factors that impact patients’ ability to see well now and in the future, the term environment encompasses a wide array of variables, including:

• Climate: Altitude and outdoor conditions can impact Healthy Sight in a variety of ways. Exposure to potentially damaging sunlight and UVR presents long-term risk of cataract and other ocular conditions. Airborne irritants or foreign bodies can lead to allergic reactions, irritation, and inflammation. Sunlight and reflections from snow cover, water, or other surfaces creates glare. Low humidity can exacerbate dry eye.
• Geography: At high altitudes and certain latitudes UVR exposure is heightened. In city environments where air pollution is problematic, eye irritation or allergic reactions can be provoked. Ozone depletion is accentuated in some areas (particularly far southern latitudes), increasing the threat of UVR damage.
• Exposure to irritants or allergens: Such as seasonal pollen, smoke, and smog can lead to allergic reactions, eye irritation, and inflammation.
• Indoor environments: Inappropriate or inadequate indoor overhead lighting (particularly for close work) can lead to eyestrain, fatigue, and headaches. Hazardous work, or recreational environments may necessitate safety eyewear.

Occupation and Environment and Healthy Sight are explored in greater detail in the section Healthy Sight in the Future

References:

• Altinors DD, Akça S, Akova YA, Bilezikçi B, Goto E, Dogru M, Tsubota K. Smoking associated with damage to the lipid layer of the ocular surface. Am J Ophthalmol. 2006;141:1016-1021.
• Bohlman H. Communicating the ocular and systemic complications of obesity to patients. Optometry. 2005;76:701-712.
• Cheung N, Wong TY. Obesity and eye diseases. Surv Ophthalmol. 2007;52:180-195.
• Christen WG, Glynn RJ, Ajani UA, Schaumberg DA, Buring JE, Hennekens CH, Manson JE. Smoking cessation and risk of age-related cataract in men. JAMA. 2000;284:713-716.
• Christen WG, Manson JE, Seddon JM, Glynn RJ, Buring JE, Rosner B, Hennekens CH. A prospective study of cigarette smoking and risk of cataract in men. JAMA. 1992;268(8):989-993.
• Gauchard GC, Vançon G, Gentine A, Jeandel C, Perrin PP. Physical activity after retirement enhances vestibulo-ocular reflex in elderly humans. Neurosci Lett. 2004;360:17-20.
• Gauchard GC, Gangloff P, Jeandel C, Perrin PP. Physical activity improves gaze and posture control in the elderly. Neurosci Res. 2003;45:409-417.
• Glynn RJ, Christen WG, Manson JE, Bernheimer J, Hennekens CH. Body mass index. An independent predictor of cataract. Arch Ophthalmol. 1995;113:1131-1137.
• Harris A, Malinovsky V, Martin, B. Correlates of acute exercise-induced ocular hypotension. Invest Ophthalmol Vis Sci. 1994;35:3852-3857.
• Hiller R, Sperduto RD, Podgor MJ, Wilson PW, Ferris FL 3rd, Colton T, D'Agostino RB, Roseman MJ, Stockman ME, Milton RC. Cigarette smoking and the risk of development of lens opacities. The Framingham studies. Arch Ophthalmol. 1997;115:1113-1118.
• Hilton E. Exerc-eyes: effects of exercise on ocular health. OT. 2003: August 15: 45-49.
• Moeller SM, Voland R, Tinker L, et al; CAREDS Study Group; Women's Helath Initiative. Associations between age-related nuclear cataract and lutein and zeaxanthin in the diet and serum in the Carotenoids in the Age-Related Eye Disease Study, an Ancillary Study of the Women's Health Initiative. Arch Ophthalmol. 2008;126:354-364.
• Moeller SM, Parekh N, Tinker L, et al; CAREDS Research Study Group. Associations between intermediate age-related macular degeneration and lutein and zeaxanthin in the Carotenoids in Age-related Eye Disease Study (CAREDS): ancillary study of the Women's Health Initiative. Arch Ophthalmol. 2006;124:1151-1162.
• Schaumberg DA, Christen WG, Hankinson SE, Glynn RJ. Body mass index and the incidence of visually significant age-related maculopathy in men. Arch Ophthalmol. 2001;119:1259-1265.
• Transitions Optical Inc. Transitions Optical Survey Confirms that Awareness of Key Healthy Sight Factors Remains Critically Low Across the World. Press Release. May 9, 2008.
• World Health Organization. Press Release: WHO/FAO release independent Expert Report on diet and chronic disease. Available at: http://www.who.int/mediacentre/news/releases/2003/pr20/en/ Accessed May 23, 2008.