age-related disease

The Impact of Age-Related Disease

What does it mean for optometry when incidences of diabetes, age-related macular degeneration and other age-related diseases increase?

Sherrol A. Reynolds, O.D, F.A.A.O. and Nicole Patterson O.D., F.A.A.O., Fort Lauderdale, Fla.

With baby boomers aging and life expectancy increasing, our older adult population is rapidly expanding. The Centers for Disease Control and Prevention (CDC) estimate that by 2030, the number of older adults will more than double to about 71 million. Combined with the fact that aging is a major risk factor in the development of several eye diseases, visual impairment and blindness is becoming a growing public health concern.

Also, older adults are more likely to have chronic systemic diseases, with ocular manifestations, that are associated with an increased risk of cardiovascular disease (CVD). This creates an immense opportunity for optometry to make an impact with early detection, management and co-management of eye conditions in this segment of the population.

This article focuses on a few disorders that pose a threat to vision after age 40 — diabetes, age-related macular degeneration (AMD) and glaucoma — as well as chronic systemic diseases with CVD risk. By understanding the incidence rates of these disorders and the demographics of your patients, you can begin your plan to invest in the future of your practice.

Diabetes: understanding the ABCs

The incidence of diabetes has increased in the past decade due to our aging population. According to CDC estimates, diabetes affects about 24 million Americans (nearly 8% of the population), with another 5.7 million people undiagnosed.

How will diabetes impact the optometric practice?

► You will play a pivotal role in detecting the early signs of diabetic complications, such as blurred vision, and reduce the risk of associated visual impairment.

► You will have a greater role in an interdisciplinary team that manages patients who have diabetes. Other members of the team include the primary care physician (PCP), the retina specialist (if the patient shows signs of diabetic retinopathy), cardiologist, podiatrist, pharmacist, endocrinologist, dietician and family or friends who act as caregivers.

To detect and manage the disease, it's important to understand the "ABCs of Diabetes." The "A" is hemoglobin A 1c (A1C), which reveals the patient's average glucose control through the preceding three months. The recommended goal is an A1C at or below 7% for diabetic patients to properly manage their disease. Both the Diabetes Control and Complications Trial (DCCT) and the United Kingdom Prospective Diabetes Study (UKPDS) show that tight glycemic control reduces the risk of microvascular disease, including a reduction in retinopathy in diabetic patients.^1,2

Furthermore, the American Diabetes Association recently added the A1C test as a means of diagnosing diabetes and identifying pre-diabetes. An A1C of 5.7% to 6.4 % indicates pre-diabetes, and an A1C above 6.5% indicates a diagnosis of diabetes.

Another important factor that you should evaluate in all diabetic patients is blood pressure ("B"). Tight blood pressure control (a target range of less than 130/80) has been found to reduce the risk of retinopathy and microvascular disease.

Cholesterol is the "C." Along with the healthcare team, encourage the patient to take steps to lower his low density lipoprotein (LDL) cholesterol, raise his high density lipoprotein (HDL) cholesterol, and lower triglycerides, as these actions have been shown to reduce CVD events.

Diabetic retinopathy is the leading cause of new cases of blindness, and the prevalence of this complication has increased in the past few years. Recent data show that almost 30% of U.S. adults older than age 40 who have diabetes have diabetic retinopathy, with about 4% of this population having visionthreatening retinopathy.³ Despite the availability of effective therapeutic modalities for preventing or delaying visual impairment from diabetic retinopathy, the number of cases will likely increase. The number of those with diabetes will increase from 285 million in 2010 (worldwide) to 438 million in 2030, estimates the International Diabetes Foundation.

The steps you should consider in managing diabetic retinopathy:

► Perform a comprehensive dilated eye exam, optical coherence tomography (OCT), obtain digital retinal photographs. Ultrawidefield scanning laser ophthalmoscopy has also been shown effective in assessing diabetic retinopathy.

► Comanage these patients with a retinal specialist. (For tips on comanagement, see "Is Your Practice Ready for Age-Related Eye Disease?" OM, September 2009, www.optometric.com/article.aspx?article=103438.)

► Educate your diabetic patients of the importance of regular eyecare visits to reduce visual loss. Many patients who have diabetes do not understand the importance of periodic dilated fundus exams or recognize the benefits of early detection of diabetic eye disease.

► Communicate not only with the patient's PCP, but also with his pharmacist, podiatrists and nutritionists, or dieticians. It's important to remember that optometry is an integral part of an interdisciplinary, integrated healthcare team in the management of diabetes.

AMD

AMD is the leading cause of visual impairment and blindness in the older population. According to the CDC, an estimated two million people have AMD (0.06% of the U.S. population), which is expected to increase to almost three million by 2020. Meanwhile, another 7.3 million people are at substantial risk for vision loss from AMD.⁴

Improved awareness and groundbreaking treatment has led to the enhanced diagnosis and management of AMD. Nonetheless, the management of AMD remains a formidable challenge The steps you should consider in managing AMD:

► Recognize the clinical signs of AMD, and improve comanagement relationships with ophthalmologists.

► Educate patients on modifiable risk factors, such as smoking, obesity, sleep apnea and ultraviolet exposure. Additionally, patients who have a propensity to develop AMD, due to family history, may benefit from genetic testing.

► Incorporate diagnostic tests that help quantify structural changes in the macula, as these tests may aid in identifying patients at risk of developing advanced AMD.

► Discuss nutritional supplementation with at-risk patients as a means of AMD prevention.

► Evaluate macular pigment optical density (MPOD) — that is, the amount of lutein, zeaxanthin and meso-zeaxanthin in the macula. This can be beneficial, as low MPOD may be associated with an increased risk for AMD. One way to measure MPOD levels is through heterochromatic flicker photometry (HFP). This test evaluates the xanthophyll carotenoids lutein and zeaxanthin, which have been shown to prevent AMD. The two instruments currently available for MPOD measurement are the QuantifEYE (Zeavision) and MacuScope (Marco).

► Use the preferential hyperacuity perimeter (Foresee PHP, Reichert). This can differentiate between dry AMD and wet AMD. It utilizes hyperacuity, or vernier acuity, to detect defects in the central 14° of the visual field for the presence of a choroidal neovascular membrane.

► Recommend nutritional supplements. Vitamin C, vitamin E, zinc and omega 3 have been shown effective at reducing AMD risk. Lutein and zeaxanthin supplementation has also been shown to prevent AMD. Results from the Age-Related Eye Disease Study (AREDS) showed that high levels of antioxidants and zinc reduce the risk of advanced AMD and its associated vision loss.

With so many products on the market, optometry plays an important role in educating our patients about the proper use of these eye-friendly nutrients. Also, ask patients about the supplements they are currently taking, as many patients already take some form of a multivitamin. The National Eye Institute (NEI) recommends that consumers who take supplements compare the formulation of their supplement with the formula used in AREDS.

In addition, integrate an interdisciplinary approach when recommending various nutrients, as certain vitamins may be contraindicated due to an underlying systemic condition. According to the NEI, people who have chronic diseases, such as heart disease and diabetes, "should not take high dose nutrients without first talking with their doctors."

Glaucoma

Glaucoma is the number one cause of irreversible blindness. It is responsible for 9% to 12% of all cases of blindness in the United States, with about 120,000 people blinded by the disease.⁵ And the prevalence of this disease is increasing. Although everyone is at risk for glaucoma, the older population is at a higher risk. Glaucoma currently affects more than four million Americans (1.3% of the U.S. population), although only half have been diagnosed, according to the Glaucoma Research Foundation.⁵ The number of glaucoma cases will also increase due to the growing population of Blacks and Hispanics, who have an increased risk for developing this disease, according to the Foundation.

The steps you should consider in managing glaucoma:

► Provide early detection and prompt treatment, which is vital in preventing visual impairment and blindness from glaucoma.

► Incorporate new retinal imaging devices to improve the way you manage glaucoma progression.

Careful slit lamp exam, fundus exam, gonioscopy and visual field testing may be sufficient to determine glaucoma.

The recent development of several imaging devices that allow for quantitative analysis of retinal nerve fiber layer (RNFL) thickness, however, has ushered in a new paradigm of care for glaucoma patients. Some of the more commonly used machines include Heidelberg Retina Tomography (Heidelberg Engineering), scanning laser polarimetry (GDx VCC, and the new GDx PRO, Carl Zeiss Meditec), and time-domain or spectral-domain optical coherence tomography (OCT). These devices not only provide a detailed view of the optic nerve and evaluation of the RNFL, but in those cases in which the slit lamp finding and visual field test results are inconclusive, they can lead to a clear diagnosis.

One of the key findings of the Ocular Hypertension Treatment Study (OHTS) was that central corneal thickness is a significant glaucoma risk factor. Therefore, pachymetry should be performed in conjunction with the glaucoma testing mentioned above.

Implementing new imaging technologies will not only enhance your ability to diagnose and manage glaucoma, it will also improve your care of other patients, and attract those patients who seek a "leading-edge" practice.

Hypertension and hypercholesterolemia-CVD

A high percentage of chronic conditions are associated with an increased risk of CVD, which is the leading cause of morbidity and mortality in the older adult population. Hypertension and hypercholesterolemia are common with advancing age, and, thus, are associated complications of stroke, heart attack and heart failure. Not only can the ocular manifestations of these conditions lead to visual loss and blindness, they can also be an early CVD sign.

The impact on optometry:

► You will play a pivotal role in detecting modifiable risk factors for cardiovascular disease.

► You will play a significant role in reducing the amount of deaths and disability associated with CVD.

Hypertension or high blood pressure (BP) is a main predictor of CVD. Hypertension, the "silent killer," is the direct cause of 70% of the approximately five million strokes each year, according to the American Heart Association. It also increases the risk of heart disease, kidney problems, visual impairment and blindness. According to the CDC, about 74.5 million U.S. adults have hypertension. Nearly one in five individuals have hypertension, and are not aware that they have it.

Patients who have hypercholesterolemia or atherosclerosis, have an increased risk of CVD. The recommended LDL cholesterol level, a major risk factor for CVD, should be less than 130, with less than 100 ideal for patients at greater risk, while high levels of HDL cholesterol, or the "good cholesterol," is associated with a low incidence of CVD. Triglyceride levels should be lower than 150 mg/dl to reduce the risk of CVD.

The steps you should consider in managing hypertension and hypercholesterolemia:

► Perform a yearly comprehensive dilated eye exam evaluating for retinopathy, retinal occlusive disease or plaque formation. The presence of retinopathy has been found to be a significant predictor of CVD. In fact, patients with retinopathy had a 15.1% greater chance of experiencing heart failure than those with no retinopathy.⁶ Even retinopathy in patients with no preexisting CVD risk factors had a threefold increased risk for developing CVD. A recent study shows that retinal arteriolar narrowing, an early sign, is indicative of CVD.⁷

► The presence of retinopathy should alert you of the risk of potential CVD, and the need to work with your patient's PCP and cardiologist.

Conclusion: a significant role for optometry

It's time to prepare for an influx of older patients into our practices. By understanding the unique demographics of your patient base, you can determine how to move forward with investments in areas, such as equipment, facilities, staff training and patient education.

The aforementioned conditions are common diseases that your office should be prepared to handle. A comprehensive eye examination, implementing additional testing and communicating with other healthcare providers all serve as cost-effective means of early disease intervention and practice growth. And in the case of systemic disease, they may also say lives. OM

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2. Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 38. UK Prospective Diabetes Study Group. BMJ. 1998;317:703–13.
3. Xinzhi Zhang, et al. Prevalence of Diabetic Retinopathy in the United States, 2005-2008. JAMA. 2010: 304(6): 649-656.
4. The Eye Diseases Prevalence Research Group. Prevalence of Age-related macular degeneration in the United States. Arch Ophthalmol 2004;122:564-72.
5. Friedman et al. 2004, Prevalence of Open-Angle Glaucoma Among Adults in the United States.
6. Duncan et al. Hypertensive retinopathy and incident coronary heart disease in high risk men. Br J Ophthalmol. 2002; 86(9): 1002–1006.
7. Wong TY, Klein R, Sharrett AR, et al. Retinal arteriolar narrowing and risk of coronary heart disease in men and women: the Atherosclerosis Risk in the Communities Study. JAMA 2002;287:1153–9.

Dr. Reynolds is an associate professor at the Nova Southeastern University College of Optometry. She is the clinical preceptor/attending in the college's diabetes and macular clinic and a fellow in the Optometric Retinal Society. Dr. Reynolds currently serves as the chairperson for the Florida Optometric Association Healthy Eyes Healthy People Committee.

Dr. Patterson serves as the chief of low vision and geriatrics clinics at Nova Southeastern University where she is an assistant professor. Currently, she teaches the low vision rehabilitation service at the Lighthouse of Broward and the geriatric service at Nova Southeastern. Dr. Patterson also instructs the low vision and pediatric residents at the university. Please e-mail your comments on this article to optometricmanagement@gmail.com.