Special Report. Vision. Supplement to MAYO CLINIC HEALTH LETTER. Preserving your sight as you age

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1 Special Report Supplement to MAYO CLINIC HEALTH LETTER OCTOBER 2010 Vision Preserving your sight as you age The deep blue of the ocean as it fades into the horizon. The delicate hues of spring s first flowers. The laughing face of your grandchild. Your eyes allow you to take in your surroundings in ways that often turn into lasting memories. They also help you manage day-to-day activities such as reading books, writing notes, checking your calendar, driving your car, recognizing people and places, using the phone and fixing your meals. Clear sight helps you stay safe, alerting you to danger and the unexpected. On an emotional level, your vision helps you define who you are, how you interact with others, and how you interpret facial expressions and body language. As you age, though, changes can occur in the delicate structures of your eyes and these changes can affect your vision. You may experience only minor problems, such as being unable to focus on close objects, or moreserious eye problems, such as cataracts, glaucoma or macular degeneration. The good news is that many age-related eye problems can be managed or treated with a broad array of ever-evolving medical devices and technologies, from inexpensive eyeglasses to state-of-the-art surgery. And although not every eye problem can be avoided, common-sense preventive measures, such as wearing sunglasses and regularly visiting your eye doctor, can help preserve the health of your eyes as you age. How you see The complexity and sophistication of human vision is unrivaled, even with the advent of the digital camera and 3-D television. One reason that your eyes are far superior to any existing technology is that they re made of living tissue. Your eyes move and function together in perfect synchronization. Each eyeball makes many rapid adjustments for brightness, focus and internal pressure. When you look at an object, the image is rapidly transmitted Ciliary artery Optic nerve Central retinal artery Retina Macula Choroid Vitreous Sclera Ciliary muscle Aqueous humor Pupil Lens Iris Cornea to your brain. The journey of an image to your brain includes these steps: Light passes through your cornea Your cornea is a domed layer of crystal-clear tissue that covers the front of your eye. Its convex surface bends incoming light and begins the process of focusing light rays from objects in front of you. The cornea also serves as a protective barrier against dust and other foreign objects that might damage the inside of your eye. Light is directed through your pupil Once light is transmitted through the cornea, it s streamlined through your pupil, the black area in the middle of your iris. The iris is the colored

2 2 Special Report When it s an emergency Certain signs and symptoms call for immediate medical care to avoid vision loss. Seek urgent care right away if you have a sudden flood of spots or squiggly lines (floaters) in front of your eyes, especially if accompanied by flashing lights in your peripheral vision. A sudden increase in floaters may indicate a tear in your retina or that your retina has pulled away from the back of your eye (retinal detachment). This can quickly lead to permanent damage and possibly blindness if left untreated, even for two or three days. Also seek immediate help if you experience: Severe eye or head pain Sudden blurring of vision Appearance of colored circles, rays or halos around lights Nausea and vomiting with some of the above signs and symptoms These may be signs and symptoms of acute angle-closure glaucoma, which is caused by a sudden closure of the angle between your iris and cornea. As a result, the pressure in your eye builds rapidly, potentially causing vision loss within hours. part of your eye. This ring of tissue includes some pigment and small muscle fibers that expand and contract to regulate the amount of light that s let in through the pupil. Your crystalline lens fine-tunes the focus The lens of your eye is a clear, elliptical structure located behind the iris and pupil. The lens fine-tunes the focus of light that has passed through the pupil. A circular muscle that surrounds the lens can relax or contract, and change the lens curvature so as to sharpen the focus of light on the retina. A youthful lens can change its curvature relatively quickly to focus either near or far. Your retina transforms light into electrical impulses Located at the back of your eyeball, your retina consists of millions of light-sensitive cells. When light strikes the retina, it induces a chemical reaction. This reaction generates electrical impulses that are relayed through the eye s optic nerve to the visual cortex, the seeing part of your brain. Your brain sees the image Because of the convex shape of the cornea and the lens, the image your retina receives is upsidedown and reversed. Your brain flips and turns the image and blends the slightly different viewing angles from both eyes into a real-time stream of colorful, 3-D images. Age-related eye problems Starting at about age 40, some eye problems become more common. But in general, you don t have to sit back and accept them as part of getting older. There are a variety of measures you can take to minimize or even prevent the effects of eye conditions including: Presbyopia If you find yourself frequently holding your book out at arm s length in order to read, chances are you re experiencing the initial signs and symptoms of presbyopia. By age 40, the eye s lens is less flexible, making it harder for your eyes to focus clearly on close objects and to quickly adjust between near and far. Most people eventually develop some degree of presbyopia. In many cases, wearing corrective eyeglasses is the simplest way to manage presbyopia. You may choose to purchase over-the-counter half-glasses to provide some magnification that will allow you to see objects at close distances. Prescription eyeglasses also are a relatively simple way to correct for presbyopia. If you already wear corrective lenses, your eye doctor may recommend bifocals. Bifocals have a higher focusing power in the lower part of the lenses. Trifocals can provide corrections for close, intermediate and distance vision. Or if you wear contact lenses for distance correction, you might wear reading glasses in addition to the contacts. Another option is to wear bifocal contact lenses or wear a different strength of contact lens on each eye. Your dominant eye usually the one you keep open when you look through a viewfinder is corrected for distance, and the other eye is corrected for near. Refractive surgery, which changes the shape of your cornea, may be used to improve close-up vision in your nondominant eye, but this isn t always recommended. Multifocal intraocular lens implants plastic lenses that are surgically placed inside your eyes may be another option. Until about age 65 or so, your eyes continue to change, so you ll likely need periodic changes in your prescription. After age 70, the

3 Special Report 3 Nonprescription reading glasses Most people by age 40 find they need glasses for reading. Nonprescription reading glasses with lenses of various strengths are commonly found in pharmacies and discount stores. Reading glasses may also function when worn over contact lenses that correct for distance vision. If you know the correction for your reading vision, look for lenses of that focal power. Otherwise, use trial and error by holding printed materials about 14 to 16 inches from your eyes. When you find a pair of glasses that allows you to read comfortably, that s probably the power you need. This general guide shows which focal power is commonly associated with each of several age ranges: Ages Power 40 to to to to to Over Keep in mind that you ll need prescription reading glasses if each eye requires a different power. Whether you use prescription or nonprescription reading glasses, it s a good idea to see your eye doctor whenever you notice vision changes. lenses of your eyes will have lost almost all elasticity, so you re less likely to require prescription changes. Dry eyes Tears provide an essential lubricant for your eyes and are produced by glands in and around your eyelids. Every time you blink, tears wash over your cornea, carrying away foreign matter and keeping the surface of your eyes smooth and clear. Unfortunately, tear production and tear quality decreases with age, causing dry eyes. Dry eyes can make your eyes feel hot and gritty and appear irritated, but they seldom cause eye damage. Most people over age 65 experience some symptoms of dry eyes. If you re a woman, hormone changes caused by menopause also can increase your risk of dry eyes. Certain medications, health conditions and environmental irritants can cause dry eyes, as well. Often, dry eyes can be treated using nonprescription, preservative-free artificial tear solutions. You can use these as often as needed. There are a number of different types of artificial tears, which have different mechanisms of action. Talk to your eye doctor about some of these different tear preparations. If this approach doesn t work, ointments can be used to moisten and protect the cornea for longer intervals than can artificial tears alone. Your eye doctor may recommend blocking the ducts that drain tears away from your eyes with tiny removable silicone or gel-like plugs. This may keep your natural tears in your eyes longer. Permanent closure of the tear duct openings is likely to be of benefit. Another option is the use of prescription eyedrops to increase your production of tears. If there s an underlying condition causing your symptoms, treating the condition may help improve your dry eyes. Your eye doctor also may recommend enriching your diet with foods containing high levels of omega-3 fatty acids or taking omega-3 fatty acid supplements. This recommendation is based on studies that suggest a high intake of omega-3 fatty acids decreases the risk of dry eyes. Cataracts A cataract is a clouding of the lens in your eye. As you age, your eye lens becomes stiffer, thicker and less transparent. Protein fibers in the lens break down A clouded lens from a cataract progressively turns clear vision (above) into blurred or dimmed vision (below).

4 4 Special Report Eye floaters Filling about 80 percent of your eye, from the back of the lens to the retina, is a clear, jelly-like substance called the vitreous. With age, microscopic fibers within the vitreous slowly shrink, grow together and become slightly stringy. Clumps of these fibers block some of the light passing through the vitreous and cast tiny shadows on the retina. You see these as fine dark specks, threads or squiggly lines floating in front of your eyes. As you age, these floaters can become more numerous. Most of the time, they re just an annoyance and eventually settle in the lower portion of your eye, becoming less bothersome. But if you see a sudden cloud of them, seek urgent help. This can be a sign that your retina has torn away from the back of your eyeball. When vision improves Some older adults are surprised by what s called second sight. After using reading glasses or bifocals for years, you suddenly discover you no longer need the reading correction. This happens when the lens of your eye becomes thicker with age. It produces some nearsightedness, which can correct your presbyopia at the same time. But not all of the news is good. The vision change is usually a sign that a cataract is forming. Inform your eye doctor if you notice the development of second sight. and clump together and start to take on a whitish or yellow-brown color. The process is painless and gradual and can develop in one or both eyes. But the resulting cloudiness changes the refractive ability of your lens, so that light entering your eye is scattered and the lens can t project a sharp, focused image onto your retina. The result is increasingly blurred vision often combined with sensitivity to bright light and glare. Most people over 60 have some degree of cataract formation. In general, a cataract isn t harmful to the health of your eye. In the early stages, your eye doctor may recommend a new eyeglass prescription or a magnifying glass to increase the sharpness of your vision. Wearing full-spectrum ultraviolet (UV) protection sunglasses and brimmed hats can decrease glare. Because cataracts tend to progress, it s important that you have regular follow-up visits with your eye doctor. This allows you and your doctor to monitor the cataract and make informed decisions about further treatment. In some cases, a cataract may eventually disrupt your vision enough to affect your quality of life and independence. At this point, you may wish to have the cataract removed and replaced with a clear, artificial lens implant. Your eye doctor can help you decide whether and when cataract surgery would be a good choice for you. Cataract surgery is usually an outpatient procedure lasting less than an hour. Typically, you need only local anesthetic, which means you re awake during the operation. Two methods are used for cataract surgery: Using an ultrasound probe to break up the lens for removal During a procedure called phacoemulsification (fak-o-e-mul-sih-fih- KA-shun), your surgeon makes a tiny incision in the front of your eye and inserts a needle-thin probe. The probe transmits ultrasound waves that break up (emulsify) the cataract. Fragments of tissue are then suctioned out. The very back part of your lens (the capsule) is left in position to serve as a place for the artificial lens to rest. In this procedure, stitches may or may not be used to close the tiny incision. Making an incision in the eye and removing the lens A less frequently used procedure called extracapsular cataract extraction requires a larger incision than is made during phacoemulsification. Through this incision, your surgeon uses surgical tools to remove the cloudy portion of your lens and uses suction tools to remove additional portions of the lens. This procedure usually requires stitches. After the cloudy lens is removed, your eye surgeon inserts an intraocular lens (IOL), which becomes a permanent part of your eye. Intraocular lenses can be monofocal or multifocal. Monofocal lenses are the most commonly implanted lenses, and they have one power. They are fixed-focus lenses, which are generally designed to focus in the distance. With this type of lens, you most likely will require reading glasses to see near. Multifocal intraocular lens implants function similarly to bifocal eyeglasses. They offer different powers in different areas of the lens to allow for distance, intermediate and near vision. However, multifocal lenses can cause problems with night vision and glare for some people. Intraocular lens implants designed to change focus with muscle contractions within the eye have not been entirely satisfactory, but newer versions are being developed.

5 Special Report 5 Using eyedrops If you have glaucoma and your eye doctor has prescribed medicated eyedrops, it s important to use them exactly as your doctor has instructed. Eyedrops can be tricky to get in your eye, and it may feel like most of the medication ends up on your face. The Glaucoma Research Foundation offers these tips: Wash your hands before putting in your eyedrops. Avoid touching the dropper tip to any part of your eye. Tilt your head backward or lie down flat, face up. With your index finger placed on the soft spot just below the lower lid, gently pull down to form a pocket. Let a drop fall into the pocket. Slowly let go of the lower lid. Close your eyes but try not to squint, as this may push the drops out of your eye. Gently press on the inside corner of your closed eyes with your index finger and thumb for a full two to three minutes. This will help prevent the drops from passing through your tear drainage canals into your nose. Blot around your eyes to remove any excess. If you re putting in more than one drop into the same eye, wait a few minutes before putting in the next drop. If you re having trouble getting the drop in, try closing your eyes first. Place a drop in the inner corner of your eyelid and slowly open your eyes, allowing the drop to roll into your eye. Gently close your eyes again and press as described. After surgery, you usually can resume normal activities by the evening of the same day. It takes about four to six weeks for the eyes to heal completely. Once your eyes have healed, your eye doctor can assess your need for eyeglasses or contact lenses. Most people need eyeglasses after cataract surgery, at least for some activities. Cataract surgery leads to improved vision in about 90 percent of people who have it, and complications are uncommon. But risks do exist, including inflammation, bleeding, swelling, retinal detachment, increased pressure inside the eye and lens dislocation. It s important to discuss both the risks and the benefits of cataract surgery with your eye doctor or surgeon before proceeding with the operation. Glaucoma Glaucoma is a group of eye diseases characterized by damage to the optic nerve, which is a bundle of more than a million nerve fibers at the back of your eye. The optic nerve sends electrical impulses to your brain, which interprets the impulses as images. Damage to the optic nerve is usually, but not always, associated with abnormally high pressure inside your eyeball. This pressure comes from a buildup of aqueous humor, a fluid naturally produced in the front of your eye. Aqueous humor normally exits your eye through a drainage system (trabecular meshwork) at the angle where the iris and the cornea meet. When the drainage system doesn t function properly, the aqueous humor can t filter out of the eye at its normal rate, and pressure builds within your eye, causing damage to the optic nerve. The most common form of glaucoma, primary open-angle glaucoma, develops so gradually that you may not notice you have it until you begin to lose your peripheral vision. Left untreated, glaucoma can eventually cause blindness. The key to early detection and protection against the effects of glaucoma is to visit your eye doctor regularly for comprehensive eye exams. Although the exact cause of primary open-angle glaucoma is yet to be identified, it s most common if you re over age 60, are black or have a family history of glaucoma. Glaucoma can be controlled, but not cured. The good news is that with treatment, your eyesight can be preserved. The main goal of treatment is to reduce the pressure in your eyeballs. Prescription From normal vision (above) glaucoma gradually progresses to early-stage glaucoma (below).

6 6 Special Report Bifocals, trifocals and progressive lenses Monofocal lenses are eyeglasses that correct one form of vision deficiency nearsightedness, farsightedness or an uneven curvature of the eye lens (astigmatism) that causes image distortion. Multifocal lenses combine two or more focal powers in one lens. By the time they reach their 40s, most people need to consider using one of these multifocal styles: Bifocals This style combines two focal powers. The top part of the lens provides your distance vision, while the lower part is for reading vision. Trifocals The trifocal lens adds a third power for an intermediate focus between your focus for distance and focus for reading. The added power helps you clearly see objects approximately two to four feet away, such as a computer monitor or items on a grocery store shelf. Progressive Unlike a trifocal lens, a progressive lens has no division lines separating the focal powers. Instead, the focal powers change smoothly as your eyes move from top to bottom. Some progressive lenses may distort vision along the bottom edge. However, newer lenses have less distortion. It may take practice to adjust to multifocal lenses. The first step is to make sure the frames are properly adjusted to fit your head. Tilt your head up and down. Your line of vision should move smoothly from one focal power to the other in both eyes at precisely the same time. eyedrops are usually the first line of treatment to lower the pressure by reducing the production of aqueous humor in your eye or increasing drainage. If these don t work, surgical procedures are available. Don t forget to mention your eyedrops if another doctor asks about any drugs you re taking. Treatment is generally lifelong, and regular checkups are needed to make sure your medication is maintaining a satisfactory eye pressure. Surgical procedures are usually undertaken when medications aren t lowering your eye pressure enough. One method of surgery, laser trabeculoplasty, uses a laser to help open up your eye s drainage system so that fluid drains out more easily. This procedure may be an alternative if you can t tolerate medications. But its effects usually last only a few years, and the procedure may need to be repeated. Other nonlaser surgeries may involve creating an alternative drainage passage for the fluid to flow out (filtration surgery) or implanting a small tube or shunt to facilitate draining. These methods are generally used if eyedrops and laser surgery aren t effective in controlling your eye pressure. Age-related macular degeneration Age-related macular degeneration (AMD) is a chronic eye disorder that occurs more commonly after age 50. It results primarily in the loss of central vision. It s marked by deterioration of the macula, a spot of densely packed specialized cells centered at the back of your retina. These cells allow you to see color and fine detail. Damage to these cells can leave you with a blind spot in the central portion of your vision. There are two types of AMD dry and wet. With dry AMD, initial changes occur in the retinal pigment epithelium (RPE), a thin layer of tissue sandwiched between the photosensitive cells Laser trabeculoplasty uses a laser to help open up your eye s drainage system so that fluid drains out more easily. From normal vision (above), your eyesight is impaired as macular degeneration develops. Eventually, a blind spot may form at the center of the visual field (bottom).

7 Special Report 7 Supplements to slow macular degeneration Taking high doses of the vitamins A, C and E and the minerals zinc and copper slows the progression of dry macular degeneration. A study conducted by the National Eye Institute, called the Age-Related Eye Disease Study, found that a specific vitamin and mineral supplement formulation reduced the risk of dry macular degeneration from advancing to more-severe cases by up to 25 percent for some participants. The formulation consisted of daily doses of: 500 milligrams (mg) of vitamin C 400 international units (IU) of vitamin E 15 mg of betacarotene (25,000 IU of vitamin A) 80 mg of zinc (zinc oxide) 2 mg of copper (cupric oxide), to prevent copper deficiency anemia, a condition associated with high zinc intake Discuss supplement treatment options with your primary care doctor or your eye doctor before taking supplements, especially if you already take other medications or supplements. Avoid betacarotene if you ve ever been a smoker, as there s evidence that the supplement may increase risk of lung cancer. Another National Eye Institute-sponsored study under way is testing the benefits of treatment with the antioxidant lutein and omega-3 fatty acids in halting or slowing dry macular degeneration. of the retina and a layer of blood vessels. The choroid is the nourishing vascular coat of the eye that extends from the iris back to the optic nerve. The choroid lies between the retina and the tough outer shell of the eye called the sclera. The RPE forms the outermost surface of the retina and provides a critical passageway for nutrients and waste products between the retina and the choroid. As the eye ages, cells in the RPE begin to deteriorate (atrophy) and lose their pigment. As a consequence, the RPE becomes less efficient in removing waste. When that happens, the normally uniform reddish color of the macula (as seen with an ophthalmoscope) often takes on a mottled appearance. Drusen clumps of waste deposit begin to appear under the retina. As the drusen and mottled pigmentation continue to develop, they interfere with light-sensitive cells in the macula, causing patchy loss of vision. Most people with macular degeneration have the dry form. Dry AMD tends to progress slowly, and some people may not be bothered by it unless they live to a very old age. Although there s no specific treatment for dry AMD, there s evidence that certain vitamins and minerals in your diet may help slow the progression of AMD. You can take these vitamins and minerals in the form of supplements, but getting them from whole fruits, vegetables and other foods may provide even greater benefits. The wet form of AMD is characterized by abnormal blood vessels that grow from the choroid into the space underneath the RPE and the retina. Plasma and blood can leak into the tissues thus the term wet and destroy light-sensitive cells. Almost all cases of wet AMD start out as the dry form. Although wet AMD accounts for only 10 to 15 percent of AMD cases, it accounts for about 80 percent of severe vision loss in people with AMD. Wet AMD also progresses much more rapidly than does dry AMD. If you notice dark spots in the center of your vision or wavy visual distortions, these may be signs of wet AMD. See your eye doctor promptly. Early diagnosis and treatment can stop or slow the disease s progression, providing you an opportunity to preserve as much vision as possible. One of the most common and effective treatments for wet AMD is the use of anti-angiogenic medications. These medications, which are injected directly into the eye, prevent or retard the growth of new abnormal blood vessels by blocking the effects of a growth factor that these blood vessels need to thrive. The two main medications used are ranibizumab (Lucentis) and bevacizumab (Avastin). Repeated injections are needed to maintain the therapy s benefits. Other older therapies for wet AMD include photocoagulation and photodynamic therapy. These destroy the abnormal blood vessels beneath the retina. These procedures have certain drawbacks and are also limited by where and to what extent the vessels have formed. Research into treatments for macular degeneration is ongoing, so ask your eye doctor for an update on treatments at your regular visits. Visiting your eye doctor A visit with your eye doctor for a comprehensive eye exam usually begins with your eye doctor asking questions about your medical his-

8 8 Special Report Diabetes and your eyes People with diabetes are 25 times more likely than others to become blind. Chronic high blood sugar can damage the tiny blood vessels that nourish your retina, eventually leading to vision loss. This complication of diabetes is referred to as diabetic retinopathy. The longer you have diabetes, the more likely you are to develop diabetic retinopathy. In its early stages, the walls of the blood vessels in your retina weaken. Most people with early diabetic retinopathy don t notice symptoms unless fluid leaks into the macula, resulting in blurred vision. As the condition progresses, it may trigger the formation of new, fragile and weak blood vessels in the retina (proliferative diabetic retinopathy). If a fragile blood vessel ruptures and bleeds, sudden vision loss can occur. Scar tissue formation around the new vessels also can pull on the retina, causing the retina to detach from the eyeball (retinal detachment). If the new vessels interfere with the flow of fluid in the eye, pressure may build, leading to glaucoma. If you have diabetes, see your eye doctor regularly for dilated eye exams. It s important to detect diabetic retinopathy in the early stages. Careful management of your diabetes is the best way to prevent vision loss. If you re in the advanced stages of diabetic retinopathy, different laser treatments can seal leaking blood vessels and eliminate abnormal blood vessels. tory including any eye problems you ve had and about your family s history of eye disease. Other tests and procedures your eye doctor may perform during an eye exam include: External eye exam Your doctor will check the external appearance of your eyes along with the supporting structures. Your pupils will be evaluated to see if they respond normally. The position and movement of your eyes, eyelids and lashes also may be checked. Your cornea and iris can be checked with magnification using a slit-lamp biomicroscope. Visual field test (perimetry) This test shows whether you have difficulty with your peripheral vision. There are several ways to do this test, but often you re asked to sit in front of a screen and press a button each time you see a flash of light on the screen. Test results map your responses and pinpoint gaps in your peripheral vision. Glaucoma, for example, has characteristic patterns of visual field loss. Visual acuity test This is the classic test that asks you to read a chart of different-sized letters up close or across the room. The goal is to gauge the sharpness of your vision. Refraction assessment This test, which requires you to look through varying lens powers, helps your eye doctor determine a corrective lens prescription if you re nearsighted or farsighted or have astigmatism or presbyopia. Slit-lamp examination A slit lamp is a microscope that uses as illumination an intense line (slit) of light. Your doctor uses the slit lamp to examine a cross section of your cornea, iris and lens under high magnification. Retinal examination This is an examination of the structures at the back of your eye, including your retina and optic nerve. Your pupils are dilated for this exam. Your doctor may use various viewing devices, such as an ophthalmoscope or a slit lamp, to look at your eye. Glaucoma test (tonometry) Tonometry measures the pressure inside your eyes (intraocular pressure) by measuring the amount of force needed to indent your cornea. The brief, painless indentation is generally made by touching a small, flat-tipped cone to your cornea. A less accurate method involves using a puff of air instead of the flattipped cone. Fluorescein angiography In this test, a dye (fluorescein or indocyanine or both) is injected into your bloodstream. As the dye circulates through the blood vessels in your choroid and retina, a camera takes pictures of your vessels every few seconds for several minutes. With the use of special light filters inside the camera, the blood vessels can be seen crisply outlined in contrast with other tissues. The pictures help your eye doctor assess damage to normal blood vessels or identify new, abnormal vessel growth associated with wet AMD. The images also help define the relationship of these blood vessels with specific retinal structures. One of the best ways of protecting your vision is by having regular eye exams. Periodic visits to your eye doctor help detect eye problems early and make sure your vision is the best it can be Mayo Foundation for Medical Education and Research, Rochester, MN All rights reserved. To inquire about your subscription, call Customer Services at ISSN MC Printed in USA