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Patient FAQ’s

question 20signWe want to make sure that you receive all of the information that you need to make educated decisions about your eye health. Our eye doctor, Dr. Donald Knapp is always available to answer your questions. Please feel free to send us your eye care questions to



Q: What is astigmatism?

Dr. Knapp: While “astigmatism” is a type of refractive error along with “farsightedness” and “nearsightedness,” it is not as well understood. Each of these types of refractive errors is so-called because each affects how the eye bends, or refracts, light. In the case of astigmatism, the cornea, which is usually round (like a basketball), is more conical in shape (like a football). As a result, the eye is rendered incapable of focusing incoming light on a single point on the retina, and vision is blurred at any distance. Fortunately, astigmatism is easy to detect during a comprehensive eye exam. Just as easily, this type of refractive error can be corrected through the use of prescription eyeglasses or contact lenses. Most people have some degree of astigmatism, which frequently occurs with nearsightedness and farsightedness.

Q: What is macular degeneration?

Dr. Knapp: Most people would probably name glaucoma and cataracts as the most common causes of vision impairment. However, new research shows that a less familiar eye disease is most responsible for vision loss and has been so for the past two decades. According to a study of 5,000 individuals, 44% of those with severe visual impairment suffered from late age-related macular degeneration (AMD). Researchers noted that rates of this condition have changed little over the past 20 years, and many people do not know what it is. The disease, which causes deterioration of the central part of the retina (macula), may be caused by smoking, oxidative stress, high blood pressure, and/or abnormal cholesterol. The risk of AMD also increases with age. There is no cure for AMD, but AMD treatments may prevent severe vision loss or slow the progression of the disease.

Q: My child is very active and I’m worried his glasses will shatter and damage his eyes?

Dr. Knapp: All parents want their children to be healthy and happy, and the same applies to anyone fitting a child for prescription eyeglasses. To ensure health, most experts agree that polycarbonate is the best choice for the lens material because it has outstanding impact resistance, excellent durability, and is light weight. Parents will want their children to wear eyeglasses with these “shatterproof” lenses since they protect young eyes from the impact of airborne objects and falls.

Q: As I get older is there anything I can do to help preserve my eyesight?

Dr. Knapp: Age is usually one of the factors most strongly associated with many eye diseases that cause “visual impairment,” defined as sight loss that is caused by eye disease, injury, or a medical condition that cannot be corrected by glasses or contact lenses. While there is no stopping the march of time, there may be some other ways to prevent visual impairment. According to recent research involving nearly 5,000 adults aged 43 to 84 over a 25-year period, those who exercised three or more times per week were 58% less likely to develop vision problems than their inactive counterparts.

Q: What is double vision (diplopia)?

Dr. Knapp: As the term implies, “double vision” (diplopia) is the simultaneous perception of two images of a single object all or some of the time. These double images may be overlapping, or each may stand distinctly on its own. Causes of double vision may range from something as simple as a case of dry eye to conditions as serious as diabetes and brain tumors.

For this reason, double vision is not something to be overlooked. If you are experiencing double vision, have an eye professional make a diagnosis of the cause. If double vision cannot be reversed, there are treatments that can help people live with the condition, including special prism glasses to minimize the effect of double vision.

Double vision that’s new or unexplained needs urgent medical attention. With so many potentially serious causes for double vision, it’s important to discover the reason without delay.

Q: What can happen to my eyes as I age?

Dr. Knapp: As people get older, they come to recognize that they are at greater risk for developing cataracts and glaucoma.However, relatively few seniors understand that “age-related macular degeneration” (AMD) affects more than 9 million Americans and continues to be the leading cause of visual impairment in the United States.According to recent research that tracked vision loss in nearly 5,000 patients over two decades, AMD is still responsible for severe vision loss in about 15 percent of Americans aged 85 years and older despite advances in prevention and treatment.

Early symptoms of the more common “dry” form of AMD include poor adaptation to dim light, while the less common “wet” form of the disease produces wavy and blurred vision.

Researchers have found links between AMD and some lifestyle choices, such as smoking. You might be able to reduce your risk of AMD or slow its progression by making these healthy choices: Avoid smoking, exercise regularly, maintain normal blood pressure and cholesterol levels, and eat a healthy diet rich in green leafy vegetables.

Q: If I have 20/20 vision does that mean my eyes are perfect?

Dr. Knapp: Those with 20/20 vision can see a letter of the same size on the eye chart that most people without refractive errors can see. While this test of visual acuity may be perfect, other facets of vision are equally important.

For instance, vision may be blurred at nearer distances, which is important to note because most reading is done at a distance closer than 20 feet. A comprehensive eye exam will also note how well focus changes from far to near and back to far again.

In addition, the eyes must work in tandem as they follow objects be able to converge rapidly or point to a moving object simultaneously. Comfortable and efficient vision involves more than visual acuity.

Routine eye exams can detect vision problems, eye disease and general health problems before you are aware a problem exists. Even though children may have passed school vision screenings and do not complain about their eyes, it may be that they are deficient in any of a number of vision skills required to read well.

Aside from visual acuity (the ability to see objects clearly), visual fixation skill is needed to aim the eyes accurately. “Static fixation” is the ability to focus on a stationary object when reading a word or working a math problem, and “saccadic fixation” is the ability to move the eyes quickly and accurately across a page to read print.

A comprehensive eye exam also includes an assessment of accommodation, binocular fusion, convergence, field of vision, and visual perception.

Q: What does it mean is a person’s eyes cross?

Dr. Knapp: The visual defect known as “strabismus” is characterized by eyes that are misaligned and point in different directions. One eye may look straight ahead while the other turns inward, outward, upward, or downward. Strabismus may cause reduced vision or amblyopia (“lazy eye”) in the weaker eye. The brain will recognize the image of the eye that sees better while ignoring the image of the weaker, or amblyopic, eye. This occurs in approximately half the children who have strabismus. Amblyopia is often treated by patching the “good” eye to strengthen and improve vision in the weaker eye.

Q: What causes myopia ( nearsightedness )?

Dr. Knapp: Because myopia (nearsightedness) is much more common now than it was four decades ago, researchers have tried to find possible reasons. Among the most plausible findings came from an analysis of eight carefully selected studies on the association between time spent outdoors and myopia among children and adolescents. After analyzing the behavior and degree of nearsightedness among more than 10,400 youngsters, researchers concluded that the chance of being nearsighted fell by approximately two percent for each additional hour spent outdoors per week. Playing outdoors allows children to focus on distant objects rather than playing with iPads, watching TV, playing video games, and doing near work, which may also play a role in nearsightedness development.

Q: What is Color Blindness?

Dr. Knapp: While people with normal vision can differentiate between more than 100 different hues, 1 person in 100 has the severe form of color blindness known as “dichromacy,” which restricts the number of colors seen to two—yellow and blue. To the dichromat, red, yellow, orange, and green all appear as yellow, while blue and violet appear to be blue. All other colors appear to be white. Color perception comes from cone cells at the center of the retina, which have three classes of light-activated pigments. Color deficiency arises from a lack or an abnormality of these pigments. As color coding takes on increased importance in everyday activities.

Q: How do I tell if I am developing glaucoma?

Dr. Knapp: The real tragedy behind vision-stealing glaucoma is that most people afflicted with this eye disease do not even realize they have it. As a result, the condition goes undiagnosed and untreated, which too often leads to unnecessary blindness. Of the 2.7 million people in the United States with glaucoma, half are undiagnosed. Most are lulled into a false sense of confidence because glaucoma often displays no symptoms in its early stages. By the time it begins to affect vision, any lost sight is impossible to regain. The risk of developing glaucoma begins to increase dramatically at midlife, which is why everyone should have a baseline exam by age 40. The most important concern is protecting your sight. Doctors look at many factors before making decisions about your treatment. If your condition is particularly difficult to diagnose or treat, you may be referred to a glaucoma specialist. While glaucoma is most common in middle-aged individuals, the disease can strike at any age, with those having a family history of the disease being especially vulnerable.

Q:What are floaters and are they dangerous

Dr. Knapp: Older individuals sometimes notice spots and specks floating across their fields of vision, particularly when looking up at the sky or other solid-hued backgrounds. While these “floaters” may initially arouse concern, they are generally nothing to worry about. These floating thread-like fragments are actually strands of collagen (a protein) that commonly occur as a result of shrinkage of the “vitreous humor” (the gel-like substance inside the eye). As we age, the vitreous humor shrinks and the fine collagen fibers it contains become thread-like. Like clouds in the sky, they can block the light hitting the retina, thereby creating shadows that we see as floaters. No treatment is required, but sudden increases or sudden flashes of light should prompt immediate treatment. Although seeing “floaters” typically does not signal a problem, there are some instances where a retinal detachment may occur. Just as you routinely have your teeth cleaned and blood pressure checked, you should also have your eyes examined. Floaters most often occur among people between the ages of 50 and 75, especially in very nearsighted individuals and cataract patients.

Q: What is macular degeneration?

Dr. Knapp: Age-related macular degeneration (AMD) affects an area of densely packed cells at the back of the eye (macula) that is responsible for central vision. At first, AMD may make it harder to see small print or close objects. Later, vision becomes blurry, and spots may cover the center of the visual field. There are two types of AMD, dry and wet. AMD starts out in the dry form, in which a nourishing layer of tissue under the macula gradually deteriorates and thins, leading to damage of the overlying light-sensitive cells of the retina. In the wet form, new, abnormal blood vessels grow behind the macula. These vessels leak blood and fluid, which can damage the central retina. Age-related macular degeneration (AMD) causes distorted central and color vision and makes it difficult for a person to read, drive, or do hobbies such as knitting or painting. The condition may be hardly noticeable in its early stages. Sometimes only one eye loses vision, while the other eye continues to see well for many years. Age-related macular degeneration (AMD) can make it very difficult to read or recognize faces.

Q: How important is nutrition for my eyes?

Dr. Knapp: Nutrition is very important for the long term health and prevention of chronic eye problems like dry eyes, cataracts and macular degeneration. a diet that is rich in antioxidants which include vegetables like kale and spinach, and red tomatoes include lutein, zeaxanthin and lycopene is known to reduce macular degeneration, cataract changes. Also omega-3 fatty acids in fish oil and bilberry extract are good for dry eyes and reduces ocular inflammation. Other extracts like goju and acai are also known to have high antioxidant properties. A good diet is related to good eye health, so it is very important to watch what you eat!

Q: What are those dark spots that I see in front of me sometimes?

Dr. Knapp: Dark specks, squiggly lines, and other shadowy shapes are caused by tiny clumps of debris that float around in the gel inside the eyeball. Floaters are most commonly seen against a clear, bright backdrop such as a cloudless blue sky. While they may develop at any age, they are most commonly experienced by older individuals. For the most part, these slightly bothersome specks are nothing to worry about unless they appear suddenly, in large numbers, and are accompanied by vision changes. Although seeing “floaters” typically does not mean a serious problem, there are some cases where they are a sign of a retinal tear or detachment . Floaters that appear suddenly and are accompanied by vision changes, and spontaneous flashes of light in the visual field may be indicative of a retinal tear or detachment, which requires immediate treatment.

Q: Why do I have dark circles under my eyes?

Dr. Knapp: Some people say that dark circles under their eyes are caused by tiredness, working too hard or even just staying up late. While this can be true, dark circles are a more often a result of the thin layer of skin below your eyes showing the blood vessels and the blood they contain more clearly than elsewhere in your body. Those dark bluish circles are usually just light being reflected back off of the blood vessels sitting just below the surface of that very thin patch of skin. Other things that can contribute to dark circles under the eyes include: medication that causes blood vessels to dilate; scratching or rubbing your eyes excessively, such as during allergy season; regularly sleeping on your stomach; and liver disease.

Q: What is Pink Eye and what can I do about it?

Dr. Knapp: “Pink Eye”, also known as conjunctivitis, is a common ocular condition which can be either allergic, bacteria or viral and each require different methods of treatment from antihistamines, antibiotics, to anti-viral medications. It may present as simple redness with itching to more severe problems like light sensitivity, eye pain and vision blur. Mucous and watery eyes is also common. It is important to seek early treatment to avoid any long term ocular problems or permanent vision changes. I am able to differentiate the different conditions and treat accordingly if you notice any of these symptoms early, please call our office.

Q: Can the wrong sunglasses be worse than none?

Dr. Knapp: When selecting sunglasses, do not allow yourself to be misled into thinking that darker lenses necessarily filter out sunlight and protect your eyes better than lighter lenses. There are lighter sunglass lenses that provide 100 percent UV protection. On the other hand, sunglasses that do not block 99 to 100 percent of the light can prove more harmful to eyes than not wearing sunglasses at all. The fact is that dark lenses make your pupils dilate, which is the eyes’ response to allow in more light. If that light is not being properly filtered to block ultraviolet rays, it can inflict more damage. Therefore, be sure the sunglasses you choose specify 99 to 100 percent UV protection on their labels.

Q: Can pregnancy affect my eyes?

Dr. Knapp: Changes in hormones, metabolism, fluid retention, and blood circulation also can affect your eyesight and vision. To begin with, water retention can lead to increases in the thickness and curvature of the eye lens, which directly affects prescription lenses’ ability to correct for refraction errors. Most women undergoing such changes find they are a bit more nearsighted than they were before pregnancy. A change in prescription is not likely needed, but some do find it necessary. In any case, these changes are temporary and will reverse themselves within several months of delivery. In addition, pregnant women are likely to experience dry eyes, which can be helped with over-the-counter lubricating eye drops.

Q: What are cataracts?

Dr. Knapp: As we age and the eyes are exposed to sunlight and other factors, the proteins in the eye lenses begin to clump together. This clouding of the eye lens is known as a “cataract.” At first, cataracts are typically small and are positioned close to the center of the lens. While both lenses are likely to be similarly affected, one may be more clouded than the other. In any case, cataracts make vision blurry and also produce glare at night. Often, people affected by cataracts may experience an increase in nearsightedness before any clouding of the lens is detected. This so-called “myopic shift” can be treated with a new eyeglass or contact lens prescription. A cataract is the clouding of the lens of the eye that is a natural part of the aging process. The number of people with cataracts is expected to grow as the population ages.

Q: What is “Low Vision”?

Dr. Knapp: The term “low vision” refers to partial sight that cannot be corrected with surgery, drugs, eyeglasses, or contact lenses. The condition can range from having unsatisfactory vision to being nearly blind. The causes of low vision include eye injury, diseases such as age-related macular degeneration (AMD), and heredity. As a result of reduced visual acuity or decreased contrast sensitivity, low-vision individuals may be unable to fully distinguish colors, see contrasts, or determine spatial relationships among objects. Fortunately, there are a variety of devices and strategies available for helping people with low vision overcome vision loss and live independently.

Q: What is amblyopia?

Dr. Knapp: Amblyopia (“lazy eye”), the most common cause of vision problems among children, occurs when the brain receives a blurred image from one eye and responds by disregarding this weaker eye’s image. The condition is entirely treatable with early intervention with an eye patch over the stronger eye, which forces the brain to recognize the weaker image. First, if there is a refractive error (nearsightedness, farsightedness, or astigmatism), corrective lenses must be prescribed. Strabismus, a condition in which the eyes do not look at the same place at the same time, may be a cause of amblyopia. Vision consists of much more than just 20/20 eyesight. Treatment consists of wearing a patch on the stronger eye to force the brain to use the other, weaker eye. Many children feel self-conscious while wearing an eye patch to correct the condition; however, research shows that, for children with moderate amblyopia, wearing an eye patch only two hours per day is as effective as wearing the patch for the standard six hours per day.

Q: What is astigmatism?

Dr. Knapp: Along with nearsightedness and farsightedness, astigmatism is a “refractive error” that results from a misshapen cornea, the clear front covering of the eye. Normally, the cornea has a smooth, round curvature. In astigmatism, the curve is elongated and greater in one direction than in another. In simple terms, the astigmatic eye is shaped more like a football than a basketball. Thus, when light passes through the cornea, it is not refracted equally in all directions. Instead, incoming images are focused on several points on the retina to create blurred and distorted vision for both nearby and faraway objects. While slight amounts of astigmatism do not affect vision, cases that impair vision can be easily corrected with prescription lenses. Most people have some degree of astigmatism, which may worsen or decrease over time.

Q: Is it normal to need reading glasses as we get older?

Dr. Knapp: Beginning at approximately age 40, most people find themselves holding reading material further from their eyes in order to see the print clearly. This loss of close-up focusing power, known as “presbyopia” (Latin for “old man’s eyes”) is caused by age-related stiffening of the eye lens, which eventually makes reading at a normal distance impossible. At this point, those with no previous need for prescription lenses often resist their need for reading glasses out of vanity, denial, or the mistaken notion that wearing glasses makes eyes weaker. However, the fact is that eyes are going to lose their near focusing ability as we get older whether or not we wear glasses, so we might as well opt for sharper vision. To help you compensate for presbyopia, your eye doctor can prescribe reading glasses, bifocals, trifocals, or contact lenses.

Q: Can vision problems cause academic difficulties?

Dr. Knapp: In some cases, a child labeled as a slow learner in school or as having ADHD may have a problem that stems more from poor vision than any learning disability or behavioral problem. Children who have seen nothing but blurred words on the blackboard or on printed pages may think that they are seeing what other children are seeing, so they will not know enough to point out the problem to parents and teachers as their grades decline. Although many schools test children with the Snellen eye chart, this test leaves 70% to 80% of eye problems undetected.

For a more comprehensive examination, children should be brought to an eye professional for a complete eye exam each year. If left untreated, some childhood vision problems can cause permanent vision loss. That’s why early identification of vision problems is crucial. Children with diagnosed vision problems should be examined annually by their optometrist.

Q: Can I tell I am developing glaucoma?

Dr. Knapp: Because those with the most common form of glaucoma (open-angle) usually do not begin to recognize symptoms of the eye disease until they have already begun to lose vision, their hopes of arresting vision loss largely rest with comprehensive eye exams. Aside from performing the simple test that measures internal eye pressure, optometrists also look directly at the optic nerve (after the pupil has been dilated) for signs of damage. In addition, a test of the patient’s visual field is performed. Unless open-angle glaucoma, which accounts for 90% of all cases, is detected through regular and thorough eye exams and properly treated in its early stages, it can cause permanent visual damage. Glaucoma is truly “the sneak thief of sight.



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