facts about your eyes

Computer Vision Syndrome (CVS)

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Computer Vision Syndrome is a condition resulting from extended use of display devices such as computers, tablets, or cell phones. Though often temporary, the condition can result in symptoms such as blurred visions, headaches, redness of the eye, dry eyes, double vision, or dizziness. CVS affects as many as 90% of computer users who spend more than three hours a day at a computer.

Most instances of CVS are caused by one of the following: glares, poor posture, poor lighting, or uncorrected vision problems.

Addressing CVS

To mitigate the effects of extended computer use, doctors recommend following the 20-20-20 rule; take a 20-second break to view something 20 feet away every 20 minutes.

Your glasses can also help prevent eye damage! Consider upgrading to blue-light resistant lenses, which can lesson the impact of screen time.

If you think you may be suffering from CVS, schedule an appointment at one of our offices today.

Dry Eye Syndrome

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How Do I Know If I Have Dry Eye Syndrome?

Dry Eye Syndrome is caused by chronic lack of sufficient lubrication and moisture on the surface of your eye. This is more common among women. Although there is no determining factor for this, we believe dry eyes could possibly be due to hormonal fluctuations.

Symptoms You May Have Dry Eye Syndrome

  1. Blurriness
  2. Sensitivity to light
  3. Irritation from windy conditions
  4. Fatigued eyes, especially at the end of the day
  5. Irritation, or problems wearing contact lenses
  6. Gritty or scratchy feelings
  7. Excessive tearing
  8. Red eyes

If you suffer from any of the above, get in touch with your local Performance Eyecare office to take a look and possibly diagnose for treatment.

Possible Causes

  1. Heavy reading, or excessive digital device use
  2. LASIK eye surgery
  3. Prolonged contacts lens wearing
  4. Living or working in dry environments
  5. Diets lacking in fatty acids
  6. Certain prescriptions such as allergy drugs, beta-blockers, etc
  7. Deficiency of tear-producing glands
  8. Certain health conditions such as arthritis, diabetes, lupus & more

Causes Of Eye Allergies

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Many allergens (substances that can evoke an allergic response) are in the air, where they come in contact with your eyes and nose. Airborne allergens include pollen, mold, dust and pet dander. Other causes of allergies, such as certain foods or bee stings, do not typically affect the eyes the way airborne allergens do. Adverse reactions to certain cosmetics or drugs such as antibiotic eyedrops also may cause eye allergies.

Similar to processes that occur with other types of allergic responses, the eye may overreact to a substance perceived as harmful even though it may not be. For example, dust that is harmless to most people can cause excessive tear production and mucus in eyes of overly sensitive, allergic individuals. Eye allergies are often hereditary.

Allergies can trigger other problems, such as conjunctivitis (pink eye) and asthma. Most of the more than 22 million Americans who suffer from allergies also have allergic conjunctivitis, according to the American Academy of Ophthalmology.

Allergy signs and symptoms

Common signs of allergies include: red, swollen, tearing or itchy eyes; runny nose; sneezing; coughing; difficulty breathing; itchy nose, mouth or throat, and headache from sinus congestion.

What causes eye allergies?

Many allergens are in the air, where they come in contact with your eyes and nose. Airborne allergens include pollen, mold, dust and pet dander. Other causes of allergies, such as certain foods or bee stings, do not typically affect the eyes the way airborne allergens do. Adverse reactions to certain cosmetics or drugs such as antibiotic eyedrops also may cause eye allergies.

Eye allergy treatment

Avoidance. The most common “treatment” is to avoid what’s causing your eye allergy. Itchy eyes? Keep your home free of pet dander and dust, and stay inside with the air conditioner on when a lot of pollen is in the air. If you have central air conditioning, use a high quality filter that can trap most airborne allergens and replace it frequently.

Medications. If you’re not sure what’s causing your eye allergies, or you’re not having any luck avoiding them, your next step will probably be medication to alleviate the symptoms.

Over-the-counter and prescription medications each have their advantages; for example, over-the-counter products are often less expensive, while prescription ones are often stronger.

Eyedrops are available as simple eye washes, or they may have one or more active ingredients such as antihistamines, decongestants or mast cell stabilizers. Antihistamines relieve many symptoms caused by airborne allergens, such as itchy, watery eyes, runny nose and sneezing.

Decongestants clear up redness. They contain vasoconstrictors, which make the blood vessels in your eyes smaller, lessening the apparent redness. They treat the symptom, not the cause.

In fact, with extended use, the blood vessels can become dependent on the vasoconstrictor to stay small. When you discontinue the eyedrops, the vessels actually get bigger than they were in the first place. This process is called rebound hyperemia, and the result is that your red eyes worsen over time.

Some products have ingredients that act as mast cell stabilizers, which alleviate redness and swelling. Mast cell stabilizers are similar to antihistamines. But while antihistamines are known for their immediate relief, mast cell stabilizers are known for their long-lasting relief.

Other medications used for allergies include non-steroidal anti-inflammatory drugs (NSAIDs) or corticosteroids. In some cases, combinations of medications may be used.

Immunotherapy. You may also benefit from immunotherapy, in which an allergy specialist injects you with small amounts of allergens to help your body gradually build up immunity to them.

Eye allergies and contact lenses

Even if you are generally a successful contact lens wearer, allergy season can make your contacts uncomfortable. Airborne allergens can get on your lenses, causing discomfort. Allergens can also stimulate the excessive production of natural substances in your tears that bind to your contacts, adding to your discomfort and allergy symptoms.

Ask your eye doctor about eyedrops that can help relieve your symptoms and keep your contact lenses clean. Certain drops can discolor or damage contact lenses, so ask your doctor first before trying out a new brand.

Another alternative is daily disposable contact lenses, which are discarded nightly. Because you replace them so frequently, these lenses are unlikely to develop irritating deposits that can build up over time and cause or heighten allergy-related discomfort.

Why Your Sunglasses Should Be Prescription

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If you currently wear eyeglasses for nearsightedness, farsightedness or astigmatism, you should strongly consider purchasing a second pair of glasses: prescription sunglasses.

Why? Because prescription sunglasses are often the best solution when you want clear, comfortable vision outdoors or when you’re driving on a sunny day. They eliminate glare and the need for squinting in bright conditions, which can reduce vision and cause eye strain.

Even if you normally wear contact lenses and nonprescription (plano) sunglasses, there will be times when your contacts dry out or become uncomfortable – especially on the beach, where you battle the effects of sand, sun, wind and water. Prescription sunglasses enable you to be outdoors all day without these discomfort problems or the hassle of dealing with your contacts.

A better solution for driving

If you normally wear prescription eyeglasses, you face a dilemma when driving on sunny days. You can purchase “clip-on” sunglasses (or a modern magnetic version of them) for your eyeglasses. But these can sometimes scratch your lenses or can be difficult to put on without taking off your glasses – which can be dangerous when driving.

Another solution is to purchase one pair of prescription eyeglasses that have photochromic lenses – the kind that darken automatically outdoors. The problem here is that these lenses often won’t darken properly inside a vehicle because some of the sun’s UV rays are blocked by your car or truck’s windshield glass.

For convenience and comfort, the best solution for seeing in the sun is prescription sunglasses. For easy access and so you don’t forget them, store them in your car or boat so they’re always there when you need them.

Many lens styles available

Prescription sunglasses are available in a wide variety of lens materials and designs, including high index plastic and progressive (“no-line bifocal”) lenses. For boating, fishing and driving, polarized lenses offer superior glare protection from light reflecting off water and roadways.

If you plan on wearing your prescription sunglasses when playing sports, working with power tools or engaging in other activities that have the potential of causing eye injuries, choose lightweight lenses made of polycarbonate or Trivex. Lenses made of these materials are far more impact-resistant than glass or plastic sunglass lenses.

As with regular prescription eyeglasses, frame styles for prescription sunglasses are nearly unlimited. The only exception is that prescription sunglasses cannot be made in the same severe wraparound styles that some nonprescription sunglasses have. However, models with a lesser-curved wraparound style are available.

For more information on prescription sunglasses, visit All About Vision®.

Article ©2008 Access Media Group LLC. All rights reserved. Reproduction other than for one-time personal use is strictly prohibited.

What Are Progressive Lenses?

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Progressive addition lenses (also called progressives or PALs) are the most popular multifocal lenses sold in the United States. Sometimes called “no-line bifocals,” these line-free multifocals provide a more complete vision solution than bifocals. Instead of having just two lens powers like a bifocal – one for distance vision and one for up close – progressives have a gradual change in power from the top to the bottom of the lens, providing a range of powers for clear vision far away, up close and everywhere in between.

Progressive lenses provide the closest thing to natural vision after the onset of presbyopia – the normal age-related loss of near vision that occurs after age 40. The gradual change of power in progressives allows you to look up to see in the distance, look straight ahead to clearly see your computer or other objects at arm’s length, and drop your gaze downward to read and do fine work comfortably close up.

While progressive lenses typically are worn by middle-aged and older adults, a recent study suggests that they may also be able to slow progression of myopia in children whose parents also are nearsighted.

Choosing the right frame for progressive lenses

Because a progressive lens changes in power from top to bottom, these lenses require frames that have a vertical dimension that is tall enough for all powers to be included in the finished eyewear. If the frame is too small, the distance or near zone of the progressive lens may end up too small for comfortable viewing when the lens is cut to fit into the frame.

To solve this problem and to expand options in frame styles, most progressive lens manufacturers now offer “short corridor” lens designs that fit in smaller frames. Today, an experienced optician can usually find a progressive lens that will work well in nearly any frame you choose.

Different progressives for different purposes

Many different progressive lenses are available on the market today, and each has its own unique design characteristics. There are even progressive lenses designed for specific activities. For example, for the computer user, special “occupational” progressive lenses are available with an extra-wide intermediate zone to maximize comfort when working at the computer for prolonged periods of time. Other designs for office work have a larger reading portion.

Adaptation

It may take a few minutes to a few days before you are completely comfortable with your first pair of progressive lenses, or when you change from one progressive lens design to another. You have to learn how to use the lenses, so you are always looking through the best part of the lens for the distance you are viewing. You also may notice a slight sensation of movement when you quickly move your eyes or your head until you get used to the lenses. But for most wearers, progressive lenses are comfortable right from the start.

Let us help

With so many options in eyewear today, choosing the right frame and lenses can seem overwhelming. Let us help. Our professional opticians can discuss the advantages of the latest progressive lenses with you and help you find the lenses and frames that best match your needs.

Preparing for an Eye Exam

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Eyecare experts recommend you have a complete eye exam every year to keep your eyes healthy. Here are some tips on how to get the most out of your exam:

Eye Exams for Kids

Some experts estimate that approximately 5% to 10% of pre-schoolers and 25% of school-aged children have vision problems. According to the American Optometric Association (AOA), all children should have their eyes examined at 6 months, 3 years, and again when they start school. Children without vision problems or risk factors for eye or vision problems should then continue to have their eyes examined at least every two years throughout school.

Children with existing vision problems or risk factors should have their eyes examined more frequently. Common risk factors for vision problems include:

  • premature birth
  • developmental delays
  • turned or crossed eyes
  • family history of eye disease
  • history of eye injury
  • other physical illness or disease

The AOA recommends that children who wear eyeglasses or contact lenses should have their eyes examined at least every 12 months.

Eye Exams for Adults

The AOA also recommends an annual eye exam for any adult who wears eyeglasses or contacts. If you don’t normally need vision correction, you still need an eye exam every two to three years up to the age of 40, depending on your rate of visual change and overall health. Doctors often recommend more frequent examinations for adults with diabetes, high blood pressure and other disorders. That’s because many diseases can have an impact on vision and eye health.

If you are over 40, it’s a good idea to have your eyes examined every one to two years to check for common age-related eye problems such as presbyopia, cataracts and macular degeneration.

Because the risk of eye disease continues to increase with age, everyone over the age of 60 should be examined annually.

How much does an eye exam cost?

Eye exams are available in many settings so the fees can vary widely. Generally speaking, contact lens exams cost more than regular eye exams. Likewise, an additional or higher fee may be charged for specialized services such as laser vision correction evaluations.

Many insurance plans cover at least a portion of eye exam services. Check to see what your benefits are and which eye doctors in your area participate in your plan before you make an appointment. Then be sure to give your doctor’s office your insurance information to verify coverage.

What information should I take with me to my eye exam?

It’s important to have some basic information ready at the time of your eye examination. Bring the following items to your exam:

  • All eyeglasses and contact lenses you routinely use, including reading glasses.
  • A list of any medications you take (including dosages).
  • A list of any nutritional supplements you take (including dosages).
  • A list of questions to ask the doctor, especially if you are interested in contact lenses or laser vision correction surgery.
  • Medical or vision insurance card if you will be using it for a portion of your fees.

15 Facts About Your Eyes

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Eyes are very complex and interesting organs. There are seven main parts in the eye that play a role in transmitting information to the brain, detecting light, and focusing. A problem with any of these parts means a problem with your vision.

Here are 15 interesting facts about eyes that you probably didn’t know:

  1. The average blink lasts for about 1/10th of a second.
  2. While it takes some time for most parts of your body to warm up to their full potential, your eyes are on their “A game” 24/7.
  3. Eyes heal quickly. With proper care, it only takes about 48 hours for the eye to repair a corneal scratch.
  4. Seeing is such a big part of everyday life that it requires about half of the brain to get involved.
  5. Newborns don’t produce tears. They make crying sounds, but the tears don’t start flowing until they are about 4-13 weeks old.
  6. Around the world, about 39 million people are blind and roughly 6 times that many have some kind of vision impairment.
  7. Doctors have yet to find a way to transplant an eyeball. The optic nerve that connects the eye to the brain is too sensitive to reconstruct successfully.
  8. The cells in your eye come in different shapes. Rod-shaped cells allow you to see shapes, and cone-shaped cells allow you to see color.
  9. You blink about 12 times every minute.
  10. Your eyes are about 1 inch across and weigh about 0.25 ounce.
  11. Some people are born with two differently colored eyes. This condition is heterochromia.
  12. Even if no one in the past few generations of your family had blue or green eyes, these recessive traits can still appear in later generations.
  13. Each of your eyes has a small blind spot in the back of the retina where the optic nerve attaches. You don’t notice the hole in your vision because your eyes work together to fill in each other’s blind spot.
  14. Out of all the muscles in your body, the muscles that control your eyes are the most active.
  15. 80% of vision problems worldwide are avoidable or even curable.

Have any more questions about eyes? Let us help! Schedule an appointment with us today!

Glasses to Aid Kids’ computer vision

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Prevent Computer Vision Syndrome

Did you know October is considered Computer Learning Month? We’re not here to teach you how to use the computer better, but to inform you of computer vision syndrome, especially for children who are likely to use the computer more often.

Take a look at these facts and figures from Gary Heiting, OD and Larry K. Wan, OD:

  • 94 percent of American families with children have a computer in the home with access to the Internet.*
  • The amount of time children ages 8 to 18 devote to entertainment media (including computer and video games) each day has increased from 6.19 hours in 1999 to 7.38 hours in 2009.**
  • In 2009, 29 percent of American children ages 8 to 18 had their own laptop computer, and kids in grades 7 through 12 reported spending an average of more than 90 minutes a day sending or receiving texts on their cell phones.**

Sitting in front of the computer screen stresses a child’s eyes because it forces them to focus and strain a lot more than any other task. This can put them at an even greater risk than adults for developing symptoms of computer vision syndrome.

According to the American Optometric Association (AOA), parents should consider these factors affecting children and computer use:

  • Children may not be aware of how much time they are spending at a computer. They may perform a task on the computer for hours with few breaks. This prolonged activity can cause eye focusing and eye strain problems.
  • Children are very adaptable. They assume that what they see and how they see is normal — even if their vision is problematic. That’s why it is important for parents to monitor the time a child spends working at a computer and make sure they have regular eye exams as directed by their optometrist or ophthalmologist.
  • Children are smaller than adults. Since computer workstations often are arranged for adult use, this can change the viewing angle for young children. Computer users should view the screen slightly downward, at a 15-degree angle. Also, if a child has difficulty reaching the keyboard or placing their feet comfortably on the floor, he or she may experience neck, shoulder and/or back pain.

Here are tips to reduce the risk of computer vision syndrome in children, according to the AOA:

  1. Have your child’s vision checked. Before starting school, every child should have a comprehensive eye exam, including near-point (computer and reading) and distance testing.
  2. Limit the amount of time your child spends at the computer without a break. Encourage kids to take 20-second breaks from the computer every 20 minutes to minimize the development of eye focusing problems and eye irritation. (Some eye doctors call this the “20-20 rule.”)
  3. Check the ergonomics of the workstation. For young and small children, make sure the computer workstation is adjusted to their body size. The recommended distance between the monitor and the eye for children is 18 to 28 inches. Viewing the computer screen closer than 18 inches can strain the eyes.
  4. Check the lighting. To reduce glare, windows and other light sources should not be directly visible when sitting in front of the monitor. Reduce the amount of lighting in the room to match the computer screen.

Be sure to check out our large selection of high quality and designer eyeglasses!

Protect Eyes from UV Rays

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Ultraviolet rays are a danger to skin and eyes year-round. They play a contributing factor to skin damage, skin cancer and eye disorders such as cataracts. It’s important to keep in mind with kids out of school and outdoor activities planned, especially during the summer months.

“The more time you spend outdoors without protecting your eyes, the greater your risk for ocular damage,” says Dr. James Winnick, an optometrist. Rather than avoid the problem entirely by seeking refuge inside, take steps to mitigate your risk in the sun.

Consider Risk Factors

While all people need to protect their eyes from UV radiation, some populations are more sensitive than others to the sun. For example, children don’t yet have the natural protection in their eyes that adults have. That means they get most of their exposure before they are 18 years old.

Experts say it doesn’t matter who you are, protecting your eyes outdoors is crucial.

Reflecting Light is a Concern

Sunlight is reflected off water, sidewalks, buildings — almost everything — and it goes in every direction. While sunglasses and photochromic lenses protect from UV light passing through the front of the lenses, a new trend in eye protection takes on the back side of lenses as well.

A special anti-reflective treatment can now be added to the back of lenses that helps prevent UV radiation from reflecting off of them and into your eyes. The great news is that some lens brands, like UNITY, offer this “backside UV” treatment at no additional cost depending on the options you choose for your new photochromic lenses.

Don’t wait for UV exposure to get the best of your eye health. Just as you use sunblock, you should have some protection for your eyes throughout the day. This May, take steps to better protect your family.

Sunglasses at Performance Eyecare

At Performance Eyecare, we carry over 700 pairs of high quality and designer eyeglasses and sunglasses in our state-of-the-art optical centers in St. Louis and the Metro East St. Louis, Illinois areas. We have eyeglasses of all price ranges, including high-end fashion frames made from the latest materials.

Some of the designer lines we carry include: Maui Jim, Fossil, X-Games, Lafont, L.A. Eyeworks, Tom Ford, Armani Exchange, Michael Kors, Callaway, Oliver Peoples, Jaguar, Silhouette, OGI and Tom Davies.

All of our eyeglasses are covered by an unconditional warranty and we always stand behind every pair of eyeglasses should you not be completely satisfied.

Click here to schedule an appointment!

Vision over 40 – Reading Glasses Make Life Easier

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Most people have natural vision changes after they reach age 40.

Eye chart and eyeglasses, Performance Eyecare, Glasses, Designer Frames

The main issue with vision over 40 is presbyopia, which means that you find yourself holding that restaurant menu at arm’s length to see it better. When you begin to see blurry text and have trouble with computer glare it is time to get a good pair of prescription reading glasses.

Presbyopia is normal but progressive. The lens of your eye becomes less flexible and cannot focus on close objects. This is why you are suddenly holding books at a distance. Other issues can be glare or color shade distinction. Presbyopia continues to decline through your 40s and 50s but slows down by age 60.

While it is tempting to buy reading glasses at the dollar store, you will use them daily and need a comfortably fitting frame with a prescription tailored to your eyesight. Also, after age 40 it is best to have a licensed optometrist examine your eyes every two years. They are trained to look for many different kinds of eye problems, not blurry vision. Diabetes, high blood pressure and medications for various other health issues are all linked to vision changes.

Some people who wear single vision glasses balk at the idea of switching to dowdy bifocals. Consider progressive lenses, which look better than bifocals and hide the need to use reading glasses. The lens is made with a seamless integration of distance, middle and near visions. Progressive lenses fit your natural gaze with no jump in vision as you look up and down.

We’d love to talk to you about how to adapt to vision changes after age 40. Contact us to set up an appointment and explore our wide range of eyecare services.

Three Different Eye Diseases Diabetics Need to Watch Out For

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People with diabetes are at a greater risk for eye disease.

High glucose levels can damage the blood vessels in the eye, which can lead to vision loss or blindness; many eye diseases have no symptoms in the early stages, so regular eye exams are a must for diabetics.

There are many different eye diseases that can plague the diabetic; this article will focus on three particularly serious eye problems: cataracts, glaucoma, and retinopathy.

Performance eye, diabetes and eye health

Cataracts

Diabetics are 60% more likely to get cataracts, and often at a younger age than people without diabetes. Poor control of blood sugar speeds it up so tight control over your blood sugar and regular eye doctor visits are most important.

Cataracts are cloudy areas that develop within the eye lens, blocking light to the retina where images are processed and making it harder to see. They don’t cause symptoms like pain, redness or tearing. Some might even stay small enough to not affect your eyesight at all.

Large, thick cataracts are generally removed via surgery.

Glaucoma

People with diabetes are 40% more likely to get glaucoma, and the longer you have diabetes the greater your chances are. Glaucoma usually has no symptoms, but it can cause bright halos or colored rings around lights. Left untreated, it can cause an increase in eye pressure damaging the optic nerve. This can result in vision loss and blindness.

Glaucoma can be diagnosed by your ophthalmologist performing these five exams: tonometry (measuring the pressure in your eye), gonioscopy (inspecting your eye’s drainage angle), ophthalmoscopy (inspecting the optic nerve), a field vision test which tests your peripheral vision, and pachymetry, which measures the thickness of your cornea.

Treatment may include eye drops, pills, laser surgery, traditional surgery or a combination of these methods.

Diabetic Retinopathy

Diabetic retinopathy is damage to blood vessels inside the retina caused by blood sugar buildup. During the early stages there is no pain and vision is not likely to change. Over time, the walls of your blood vessels may leak fluid, and blood vessels can form scar tissue and pull the retina away from the back of your eye. This can lead to severe vision loss and possibly even blindness.

Retinopathy is diagnosed during a thorough eye exam using a special dye to find leaking blood vessels.

Treatment in early stages is a laser surgery that seals the blood vessels and stops them from leaking and growing. It can’t restore lost vision, but combined with follow-up care, it can lower the chance of blindness by as much as 90%. Later stage treatment may consist of surgery to remove scar tissue, blood and cloudy fluid from inside the eye, improving vision.

As you can see from these three different eye diseases, keeping control of your blood sugar is most important if you wish to keep your eyesight. Contact us today to find out more about how we can help.

Eye Myths and Facts

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Can using someone else’s prescription glasses harm your eyes? Will sitting to close to the television ruin your eyes? Will crossing your eyes to long make them permanently stick like that?! Everyone has heard many eye rumors, many from your parents growing up. The questions everyone has is, are they true? Below is a list of eye myths and facts. I bet you will be shocked by some of them. Don’t be afraid to share this with your parents!

Reading in poor light will hurt the eyes: Before the invention of electric light, most nighttime reading and other work was done by dim candlelight or gaslight. Reading in dim light today won’t harm our eyes any more than it did our ancestors’ eyes or any more than taking a photograph in dim light will damage a camera.

Holding a book too close or sitting too close to the television set is harmful to the eyes: Many children with excellent vision like to hold books very near to their eyes or sit close to the television set. Their youthful eyes focus very well up close, so this behavior is natural to them, and it is safe. Children and adults who are nearsighted might need to get close to a book or television set to see clearly. Doing so does not cause or worsen nearsightedness or any other kinds of eye problem.

Using the eyes too much and “wear them out”: We wouldn’t lose our sense of smell by using our nose too much or our hearing by using our ears too much. The eyes were made for seeing. We won’t lose our vision by using our eyes for their intended purpose.

Wearing eyeglasses that are too strong or have the wrong prescription will damage the eyes: Eyeglasses change the light rays that the eye receives. They do not change any part of the eye itself. Wearing glasses that are too strong or otherwise wrong for the eyes cannot harm an adult’s, although it might result in a temporary headache. At worse, the glasses will fail to correct vision and make the wearer uncomfortable because of blurriness, but no damage to any part of the eye will result.

Wearing eyeglasses will weaken the eyes: The eyeglasses worn to correct nearsightedness, farsightedness, astigmatism, or presbyopia will not weaken the eyes any more than they will permanently “cure” these kinds of vision problems. Glasses are simply external optical aids that provide vision to people with blurred vision caused by refractive errors. Exceptions are the kinds of glasses given to children with crossed eyes (strabismus) or lazy eye (amblyopia). These glasses are used temporarily to help straighten the eyes or improve vision. Not wearing such glasses may lead to permanently defective vision.

Crossing the eyes can make them permanently crossed: Our eye muscles are meant to allow us to move our eyes in many different directions. Looking left, right, up, or down, will not force the eyes to stay permanently crossed. Crossed eyes result from disease, from uncorrected refractive error, or from muscle or nerve damage, not from forcing the eyes into that position.

Having 20/20 vision means that the eyes are perfect: The term “20/20” denotes a person with excellent central vision. But other types of vision-such as side vision, night vision, or color vision might be imperfect. Some potentially blinding eye disease, such as glaucoma or diabetic retinopathy, can take years to develop. During this time, they are harming parts of the inner eye, but the central vision can remain unaffected.

http://mayoclinichealthsystem.org/locations/la-crosse/medical-services/ophthalmology/myths-and-facts