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Learning more about you Prescription: What is Presbyopia?

Presbyopia is the normal loss of the near focusing ability of your eyes that happens as we age. Many people will begin to notice the effects of presbyopia sometime after age 40, when they start having trouble seeing small print clearly — including text messages or small print on their computers.

The eye's lens stiffens with age, so it is less able to focus when you view something up close.

Presbyopia is on the rise in the United States as the population continues to age. According to the Census Bureau, approximately 112 million Americans were presbyopic in 2006. This number is expected to increase to 123 million by the year 2020.

Worldwide, an estimated 1.3 billion people had presbyopia in 2011. This number is expected to increase to 2.1 billion by 2020.

Though presbyopia is a normal change in our eyes as we age, it often is a significant and emotional event because it's a sign of aging that's impossible to ignore and difficult to hide.

Presbyopia Symptoms And Signs

When you become presbyopic, you will have to start holding your smartphone and other objects and reading material further from your eyes to see them more clearly. Unfortunately, when you move things farther from your eyes they get smaller in size, so this is only a temporary and partially successful solution to presbyopia.

Also, even if you can still see pretty well up close, presbyopia can cause headaches, eye strain and visual fatigue that makes reading and other near vision tasks less comfortable and more tiring. So the best solution is to get your eyes tested frequently to avoid these unpleasent side effects and get glasses as soon as it starts.

What Causes Presbyopia?

Presbyopia is caused by an age-related process. This differs from astigmatism, nearsightedness and farsightedness, which are related to the shape of the eyeball and are caused by genetic and environmental factors. Presbyopia generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye.

These age-related changes occur within the proteins in the lens, making the lens harder and less elastic over time. Age-related changes also take place in the muscle fibers surrounding the lens. With less elasticity, the eye has a harder time focusing up close. 

Presbyopia Treatment: Eyeglasses

Eyeglasses with progressive lenses are the most popular solution for presbyopia. These line-free multifocal lenses restore clear near vision and provide excellent vision at all distances, regardless of what refractive errors you may have in addition to presbyopia.

Another option is eyeglasses with bifocal lenses. But bifocals are much less popular these days because they provide a more limited range of vision for many presbyopes. Also, most people don't want to show their age by wearing eyeglasses that have a visible bifocal line.

Also, it's common for people with presbyopia to notice they are becoming more sensitive to light and glare due to aging changes in their eyes. Photochromic lenses, which darken automatically in sunlight, are a good solution to this. They are available in all lens designs, including progressive lenses and bifocals.

Reading glasses are another choice. Unlike bifocals and progressive lenses, which most people wear all day, reading glasses are worn only when needed to see close objects and small print more clearly.

Regardless which type of eyeglasses you choose to correct presbyopia, definitely consider lenses that include anti-reflective coating. AR coating eliminates reflections that can be distracting and cause eye strain. It also helps reduce glare and increase visual clarity for night driving. Another great addition are blue-light blocking lenses that reduce eye strain from the sun and electronics that we tend to use everyday.

How to Quickly Adjust to a New Pair of Glasses

For the everyday fashionista, multiple glasses personalities are an essential part of their everyday looks. We love seeing our fans post their collections on social media. In addition to the box and fabulous new frames that arrive in the mail, we have to be aware that there will be an adjustment period to your new glasses, frames and new lenses alike. Think of this adjustment period like a new pair of jeans or shoes, it takes a while to get used to the fit. Below is a quick new glasses adjustment “How To.”

ADAPTING TO A NEW PRESCRIPTION IN A FAB NEW FRAME

You should expect some time for your eyes to adjust to a new prescription. If you are feeling mildly off-balance or dizzy when you first wear your new prescription, don’t panic; it’s normal. It's recommended not to plan long-distance driving or overly strenuous activity during your first few days with your new prescription. Instead make low key fun plans where you can show off your new frames.

Showing off glasses to friends is perfect, because wearing your new frames as often as possible will speed up your eyes prescription adjustment. Although, your old glasses are still great, try not to wear them if they still have your previous prescription, it'll make adjusting that mush more difficult. A full adjustment process can take anywhere from a few days up to a few weeks. If after one week of constant wear of your new glasses still don’t feel right and you are experiencing headaches or blurred vision, talk to your eye doctor.

ADAPTING TO THE SAME PRESCRIPTION IN A FANCY NEW FRAME

You just bought a new pair of glasses, same prescription as your current lenses and they just fell "off". Don’t’ worry, a new frame shape sometimes needs some adjustment time, generally just a couple of days. If after a few days your new frames still are not feeling right, you may simply need an adjustment which you can get for free at most eyewear stores. For loose feeling, tightness or any uneven feelings, plan a visit to an optician for a professional adjustment.
Once adjusted and a little time those new frames should be feeling like old friends in no time.

ADAPTING TO A NEW LENS TYPE

You may be switching from a simple vision lens to a progressive, or vice versa. Or maybe you just added a new lens coating like our blue-block lenses that help with eye strain and fatigue. The adjustment to these is generally pretty quick, and will only require some slight habit changes, like in the case of progressive lenses when different parts of the lenses are different prescriptions.

ADAPTING TO DIFFERENT LENS AND FRAMES SHAPES AND SIZES

We love fun frame sizes, big and round to small and rectangular, we love them all, but frame size and curvature can also take some adjusting time. In cases of lens curvature your peripheral vision is affected, and you may be seeing clearer than you were before. Regardless, your brain will need a couple of days to process your full field of vision with the enhanced clarity the corrected curve lenses provides.

Certain frames will enter your field of vision differently – smaller frames are usually visible, while large frames can hover on the borders of your view. If your new frame causes issues after a few days it is likely a problem with the lens, not the frame – if you’ve already adjusted the frame to fit correctly consult your eyecare professional.

ADAPTING TO NEW LENS MATERIALS

You may also need time to adapt to lens materials that may differ from your standard clear lenses. New lenses such as polarized, photochromic, or blue blocker lens technology could take just a hint of time to get used to. Polarized lenses will enhance contrast and reduce glare but can also distort your view of digital screens. With photochromic lenses you might notice less discomfort with outside light, especially if you add reflective. The adjustment period will be minimal, but you may find yourself surprised the first couple of times your lenses automatically darken. The adjustment to blue blocker glasses could be more of a positive adjustment with your eyes feeling less tired and dry when you start wearing.

Learning more about your eyewear prescription: What is myopia?

Nearsightedness, or myopia, is the most common refractive error of the eye, and it has become more prevalent in recent years. Let's explore what that means

In fact, a recent study by the National Eye Institute (NEI) shows the prevalence of myopia grew from 25 percent of the U.S. population (ages 12 to 54) in 1971-1972 to a staggering 41.6 percent in 1999-2004.

Though the exact cause for this increase in nearsightedness is unknown, doctors feel it has something to do with eye fatigue from computer use and other extended near vision tasks, coupled with a genetic predisposition for myopia.

Myopia Symptoms And Signs

If you are nearsighted, you'll have difficulty reading signs and seeing distant objects clearly, but will be able to see clearly for close-up tasks like reading and computer use.

Other signs include squinting, eye strain and headaches. Feeling fatigued when driving or playing sports also can be a symptom of uncorrected nearsightedness.

If you experience these signs or symptoms while wearing your glasses or contact lenses, schedule a comprehensive eye examination with your optometrist or ophthalmologist to see if you need a stronger prescription.

What Causes Myopia?

Myopia occurs when the eye is too long relative to the focusing power of the cornea and lens of the eye. This causes light rays to focus at a point in front of the retina, rather than directly on its surface which is wjhat causes pbjects that are far away to appear blurry. Nearsightedness also can be caused by the cornea and/or lens being too curved for the length of the eye.

Myopia usually begins in childhood and you may have a higher risk if your parents are nearsighted. In many cases, nearsightedness stabilizes in early adulthood but can continue to progress with age.

Myopia Treatment

Nearsightedness is corrected with glasses, contact lenses or refractive surgery. Depending on the value of your myopia, you may need to wear your glasses or contact lenses all the time or, if your prescroption is weaker, only when you need very clear distance vision, like when driving, seeing a chalkboard or watching a movie.

Good choices for eyeglass lenses for nearsightedness include high-index lenses (for thinner, lighter glasses) and anti-reflective coating. Also, consider photochromic lenses to protect your eyes from UV and high-energy blue light and to reduce your need for a separate pair of prescription sunglasses outdoors.

If you're nearsighted, the first number ("sphere") on your eyeglasses prescription or contact lens prescription will be preceded by a minus sign (–). The higher the number, the more nearsighted you are.

Controlling Myopia

With more and more people getting nearsighted these days, there is a lot of interest in finding ways to control the progression of myopia in childhood.

A number of different techniques have been tried — including fitting children with bifocals, progressive lenses and gas permeable contact lenses — with mixed results.

Degenerative Myopia

In most cases, nearsightedness is simply a minor inconvenience and poses little or no risk to the health of the eye. But sometimes myopia can be so progressive and severe it is considered a degenerative condition.

Degenerative myopia (also called malignant or pathological myopia) is a relatively rare condition that is believed to be hereditary and usually begins in early childhood. About 2 percent of Americans are afflicted, and degenerative myopia is a leading cause of legal blindness.

In malignant myopia, the elongation of the eyeball can occur rapidly, leading to a quick and severe progression of myopia and loss of vision. People with the condition have a significantly increased risk of retinal detachment and other degenerative changes in the back of the eye, including bleeding in the eye from abnormal blood vessel growth (neovascularization).

Degenerative myopia also may increase the risk of cataracts.

Surgical treatment for complications of degenerative myopia includes a combination drug and laser procedure called photodynamic therapy that also is used for the treatment of macular degeneration.

How to Read your Eyewear Prescription

So you just had your eye exam and before you leave you are handed a little piece of paper with a bunch of numbers. At some point you may have thought to yourself ‘I wonder what they mean?’. Let's examine a sample prescription and discuss how refractive errors are measured.Before we go any further we need to explain what a diopter is. In 1872 a french Ophthalmologist, Felix Monoyer, developed a new method of measuring the focal length of ophthalmic lenses called the diopter. One diopter equals a focal length of one meter. So a lens that is -4.00diopters has a focal length of 1/4 meter. The focal length of a lens is determined by this equation, 1/diopter = focal length. So now that we know what form of measurement is used lets take a look at a sample prescription.

O.D. -3.50
O.S. -4.00

The first thing that we notice are the two initials in front of thenumbers. These designated which eye the prescription is for. O.D. stands for Ocular Dexter or right eye and O.S. stands for Ocular Sinister meaning left eye. More commonly you may see just the simple R for right and L for Left.

After the right/left eye designation you see a symbol that looks like either a minus or plus symbol. A plus lens magnifies and a minus lens minify objects. A plus lens is used in the correction of hyperopia, a condition where light comes to a focus behind the retina, the plus power of a lens brings it to focus on the retina. A minus lens is used for the correction of myopia, a condition where light comes to a focus in front of the retina, the minus power of the lens brings light to a focus on the retina.

O.D. -3.50
O.S. -4.00

The numbers highlighted above are called sphere powers. This person has ano astigmatism, meaning that the shape of their cornea is the same in all meridians.

O.D. -3.50 -1.00 x 180
O.S. -4.00 -1.25 x 170

What about astigmatism?

This next person has astigmatism. It’s correction is given in the highlighted numbers above. This means that the person has a cornea shaped more like a foot ball as opposed to a sphere. Therefore each meridian needs its correction. A football has two radii of curvature. One from point to point and the other from side to side. From point to point is a much larger radius of curvature resulting in a flatter curve. From side to side is a much smaller radius of curvature resulting in a steeper curve. An astigmatic eye will resemble these curves. For a lens to correct this it must have two meridians as well. This is were a toric or sphero-cylinder lens will be used.

The second highlighted numbers are called cylinder power. This cylinder power is the additional power needed for the correction in the second meridian. So in the above example the right eye will have -3.50 in the spherical meridian and additional -1.00 in the cylinder resulting a power of -4.50 for astigmatism correction.

To determine which meridian the cylinder power is in a 180 degree system is used, often referred to as the axis, the axis is distinguished from the other numbers by an x then the number. The typical circle after the number showing that the number is a degree isn't used. In a poorly written RX that symbol could look like a zero resulting in an axis error. On occasion you might see the cylinder power with a plus symbol in front of it. This is called writing the prescription in ‘plus cyl’. It’s just another way of writing the same prescription. To change the prescription from plus cyl to minus cyl or visa versa you would need to do the following. In our example we will change the prescription to plus cyl.

  1. Add the sphere and cyl power.
  2. Change the symbol from – to + for the cyl power.
  3. If the axis is more than 90 subtract 90. If the axis is less than 90 add 90.

Now our sample prescription has become:

O.D. -4.50 +1.00 x 90
O.S. -5.25 +1.25 x 80

To change it back you do the reverse of the above steps.  The prescription has not changed, only the way it was written.

When you get older you might need a little help reading. At the bottom of your prescription you may see:

O.D. -3.50 -1.00x 180
O.S. -4.00 -1.25x 170
ADD: 2.00

Presbyopia is a condition that causes your crystalline lens to lose some of its elasticity. This makes near vision much more difficult and requires the use of additional power to allow the wearer to read and view objects up close. Often a patient will look at their prescription and think that 2.00 is the reading prescription. To their surprise when they purchase oOTC reading glasses they just don’t work. That is because the 2.00 must be added to the distance prescription. The add power is always a plus power and when added to the prescription above, which is a negative number, we get -1.50 -1.00 x 180 for the right eye, and -2.00 -1.25 x 170 for the left. This is the patient’s actual reading prescription. It’s easy to see why the +2.00 readers wouldn't work.

At times, a person’s eyes may not work well together. In these cases, something called a prism may be prescribed. Prism actually displaces the image towards its apex. Prism is prescribed in what is termed in base up, base down, base in and base out or a combination like base in and base up. If you imagine a lens made from two prisms one stacked base to base (plus lens) and one apex to apex (a minus lens) you can get a better picture of what is meant by moving the base of the lens in or out. Often a prescription with prism looks like the example below:

    O.D. -3.50 -1.00 x 180 1Δ B.U.
O.S. -4.00 -1.25 x 170 2Δ B.U. 1Δ B.I.

The triangle placed after the number is the Greek letter Delta which stands for diopter a unit of measurement that is also used to measure the amount of prism needed for the lens. The initials stand for Base Up (BU), Base In (BI), Base Down (BD), Base Out (BO). In the case of the left eye we have a combined prism.

The eye is a very complicated system, as are the prescriptions needed for visual correction. The above examples are simplified to help the average patient understand what their prescriptions might mean but to understand in more detail what is going on with your eyes you should discuss it with your doctor.

How to Clean Your Prescription Glasses Properly

Cleaning your eyeglasses daily is the best way to keep them looking great and prevent lens scratches and other eyewear damage.

But there's a right way — and plenty of wrong ways — when it comes to how to clean glasses.

Follow these tips to clean your eyeglass lenses and frames without risk of scratching the lenses or causing other damage. These same tips apply for cleaning sunglasses, safety glasses and sports eyewear, too.

HOW TO CLEAN YOUR GLASSES

1. Wash and dry your hands thoroughly. Before cleaning your eyeglasses, make sure your hands are free from dirt, grime, lotion and anything else that could be transferred to your lenses. Use lotion-free soap or dishwashing liquid and a clean, lint-free towel to clean your hands.

2. Rinse your glasses under a gentle stream of lukewarm tap water. This will remove dust and other debris, which can help avoid scratching your lenses when you are cleaning them. Avoid hot water, which can damage some eyeglass lens coatings.

3. Apply a small drop of lotion-free dishwashing liquid to each lens. Most dishwashing liquids are very concentrated, so use only a tiny amount. Or apply a drop or two to your fingertip instead. Use only brands that do not include lotions or hand moisturizers (Dawn original formula, for example).

4. Gently rub both sides of the lenses and all parts of the frame for a few seconds. Make sure you clean every part, including the nose pads and the ends of the temples that rest behind your ears. And be sure to clean the area where the edge of the lenses meet the frame, where dust, debris and skin oils can accumulate.

5. Rinse both sides of the lenses and the frame thoroughly. Failing to remove all traces of soap will cause the lenses to be smeared when you dry them.

6. Gently shake the glasses to eliminate most of the water from the lenses. Inspect the lenses carefully to make sure they are clean.

7. Carefully dry the lenses and frame with a clean, lint-free towel. Use a dish towel that has not been laundered with a fabric softener or dryer sheet (these substances can smear the lenses). A cotton towel that you use to clean fine glassware is a good choice. Make sure the towel is perfectly clean. Dirt or debris trapped in the fibers of a towel can scratch your lenses; and cooking oil, skin oil or lotion in the towel will smear them.

8. Inspect the lenses again. If any streaks or smudges remain, remove them with a clean microfiber cloth — these lint-free cloths are available at most optical shops or photography stores.

For touch-up cleaning of your glasses when you don't have the above supplies available, try individually packaged, pre-moistened disposable lens cleaning wipes. These are formulated specifically for use on eyeglass lenses. Don't use any substitutes.

Which brings us to a very important topic — what NOT to use to clean your glasses.

Eyeglass Cleaners And Cleaning Cloths

Spray eyeglass cleaners are available from eye care professionals or at your local drug or discount store. These can be helpful if you are traveling or don't have dishwashing soap and clean tap water available.

CLEANING GLASSES - DON'TS

DON'T use your shirttail or other cloth to clean your glasses, especially when the lenses are dry. This can scratch your lenses.

DON'T use saliva to wet your lenses. (Ugh, do I even have to explain why?)

DON'T use household glass or surface cleaners to clean your eyeglasses. These products have ingredients that can damage eyeglass 

DON'T use paper towels, napkins, tissues or toilet paper to clean your lenses. These can scratch or smear your lenses or leave them full of lint.

DON'T try to "buff away" a scratch in your lenses. This only makes the situation worse.

If tap water isn't available to rinse your lenses before cleaning them, use plenty of the spray eyeglass cleaner to flush away dust and other debris before wiping the lenses dry.

If your lenses have anti-reflective (AR) coating, make sure the eyeglass cleaner you choose is approved for use on anti-reflective lenses.

When using individually packaged, pre-moistened disposable lens cleaning wipes, first inspect the lenses for dust or debris. Blow any particles off before wiping the lenses, to avoid scratching.

Microfiber cleaning cloths are an excellent choice for cleaning glasses. These cloths dry the lenses very effectively and trap oils to avoid smearing.

But because they trap debris so effectively, make sure you clean the cloths frequently. Hand-wash the cloth using lotion-free dishwashing liquid and clean water; allow the cloth to air dry.

How To Remove Scratches From Glasses

Unfortunately, there is no magic cure for scratched lenses. Once your glasses are scratched, they are scratched.

Some products are designed to make the scratches look a little less visible — but these are essentially waxy substances that wear off easily, and results are mixed, depending on the location and depth of the scratches. Also, these products often will smear lenses that have AR coating.

In addition to reflecting light and interfering with vision, scratches can affect the impact resistance of the lenses. For optimum vision and safety, the best thing to do if you notice significant scratches is to purchase new lenses.

When purchasing, choose lenses that have a durable scratch-resistant coating. And ask your optician if your purchase includes an anti-scratch warranty — especially if scratched lenses have been an issue in the past.

When To Have Your Glasses Cleaned Professionally

If your lenses are in good shape but the nose pads or other components of the frame have become impossible to keep clean, see your eye care professional.

Sometimes eyeglasses can be cleaned more thoroughly with an ultrasonic cleaning device, and yellowing nose pads can be replaced with new ones. See your optician before attempting these fixes at home.

Use A Protective Storage Case

Eyeglass lenses can easily get scratched if you fail to store them somewhere safe. This includes when you take them off at bedtime.

Always store your glasses in a clean eyeglasses case, and NEVER place them on a table or counter with the lenses facing down.

If you don't have a glasses case handy, place your glasses upside down with the temples open — somewhere safe, where they won't get knocked off a table or countertop.

Glasses Don't Last Forever

All eyeglass lenses will get a few scratches over time from normal use and exposure to the environment. (And from occasionally getting dropped or misplaced.) Eyeglasses lenses are scratch resistant, not scratch-proof.

When purchasing glasses, ask your eye care provider about anti-scratch warranties for your lenses. This is especially important for children's eyeglasses or if you wear glasses in dusty conditions.

Following the above tips is the best way to keep your glasses clean and scratch-free for as long as possible. 

How to Choose the Best Prescription Glasses Lenses for You

The lenses you choose for your eyeglasses — even more than frames — often will determine how happy you are with your eyewear. They determine the weight, feel and quality of your glasses, and with them you can add coatings to prolong the life and comfort of your glasses, like anti-reflection or blue-block.

We know that buying eyeglass lenses is not an easy task. In fact, in a recent issue, Consumer Reports magazine said, "There are so many choices for lenses and coatings, it's easy to be confused about what's worth buying."

This buying guide will help you cut through the hype about different types of eyeglass lenses and help you choose lenses and coatings that offer the best features and value for your needs.

Why Choosing The Right Eyeglass Lenses Is So Important

When buying eyeglasses, the frame you choose is important to both your appearance and your comfort when wearing glasses. But the eyeglass lenses you choose influence four factors: appearance, comfort, vision and safety.

Eyeglass lens thickness is determined in part by the size and style of the frame you choose. For thinner lenses, choose smaller, round or oval frames. Also, plastic frames hide edge thickness better.

A common mistake people often make when buying eyeglasses is not spending enough time considering their choices of eyeglass lens materials, designs and coatings. Or on the opposite end, they get information paralysis and can't choose because of the many choices offered to them.

This article gives you the basics you need to know to buy eyeglasses lenses wisely.

The following information applies to all prescription lenses for glasses — whether you need single vision lenses to correct nearsightedness, farsightedness, and/or astigmatism, or you need progressive lenses, bifocals or other multifocal lenses to also correct presbyopia.

Eyeglass Lens Materials - Features And Benefits

Glass lenses. When eyeglasses start beign manufactured, all lenses were made of glass.

Although glass lenses offer exceptional optics, they are heavy and can shatter easily, potentially causing serious injuries to the eye or even loss of an eye. For these reasons, and they weight and thickness, glass lenses are no longer widely used for eyeglasses.

In 1947, the Armorlite Lens Company in California introduced the first lightweight plastic eyeglass lenses. The lenses were made of a plastic polymer called CR-39, an abbreviation for "Columbia Resin 39," because it was the 39th formulation of a thermal-cured plastic developed by PPG Industries in the early 1940s.

Because of its light weight (about half the weight of glass), low cost and excellent optical qualities, CR-39 plastic is still a popular material for eyeglass lenses.

Polycarbonate lenses. In the early 1970s, Gentex Corporation introduced the first polycarbonate lenses for safety glasses. Later that decade and in the 1980s, polycarbonate lenses became increasing popular and remain so today.

Originally developed for helmet visors for the Air Force, for "bulletproof glass" for banks and other safety applications, polycarbonate is lighter and significantly more impact-resistant than CR-39 plastic, making it a preferred material for children's eyewear, safety glasses and sports eyewear.

A newer lightweight eyeglass lens material with similar impact-resistant properties as polycarbonate is called Trivex (PPG Industries), which was introduced for eyewear in 2001. A potential visual advantage of Trivex is its higher Abbe value (see below).

High-index plastic lenses. In the past 20 years, in response to the demand for thinner, lighter eyeglasses, a number of lens manufacturers have introduced high-index plastic lenses. These lenses are thinner and lighter than CR-39 plastic lenses because they have a higher index of refraction (see below) and may also have a lower specific gravity.

What Is Astigmatism?

Astigmatism is one of the most common vision problems, but most people don't know what it is.

Many people are relieved to learn that astigmatism is not an eye disease. Like nearsightedness and farsightedness, astigmatism is a type of refractive error - a condition related to the shape and size of the eye that causes blurred vision. 

In addition to blurred vision, uncorrected astigmatism can cause headaches and eyestrain and can make objects at all distances appear distorted.

What are the Signs and Symptoms of Astigmatism?

If you have only a small amount of astigmatism, you may not notice it at all, or you may have only mildly blurred or distorted vision. But even small amounts of uncorrected astigmatism can cause headaches, fatigue and eyestrain over time.

Astigmatism usually develops in childhood. A study at The Ohio State University School of Optometry found that more than 28% of schoolchildren have astigmatism. 

Children may be even more unaware of the condition than adults, and they may also be less likely to complain of blurred or distorted vision. But astigmatism can cause problems that interfere with learning, so it's important to have your child's eyes examined at regular intervals during their school years. 

What Causes Astigmatism?

Usually, astigmatism is caused by an irregular-shaped cornea, the clear front surface of the eye. In astigmatism, the cornea isn't perfectly round, but instead is more football- or egg-shaped. 

In some cases, astigmatism may be caused by an irregular-shaped lens inside the eye. 

In most astigmatic eyes, the irregular shape of the cornea or lens causes light rays to form two distorted images in the back of the eye, rather than a single clear one. This is because, like a football, an astigmatic eye has a steeper curve and a flatter one.

How Is Astigmatism Treated?

In most cases, astigmatism can be fully corrected with eyeglasses or contact lenses. 

Rigid gas permeable (RGP or GP) contact lenses often provide the best correction for astigmatism. But special soft contact lenses for astigmatism, called toric soft lenses, are also available. 

Hybrid contact lenses are another option. These lenses have a GP center and a soft periphery to provide the clarity of gas permeable lenses and wearing comfort that is comparable to soft lenses.

Getting to the Basics of Prescription Glasses: Definitions and Details

Prescription eyeglasses are more popular today than ever, despite the availability and affordability of contact lenses and  the advancements in vision correction surgery.

Fashionable frame styles are more in demand than ever, with the trends changing just as quickly as the clothing industry. And eyeglass frame materials have evolved with the advent of new plastics and various types of metals.

Eyeglass Frame Styles

Eyeglasses have also become quite popular as fashion accessories. Many people change their frames to match their wardrobes. Your appearance, personal taste and lifestyle should all be considered when choosing eyeglasses.  

Multi-colored inlays, composite materials, designer emblems, and enhancements such as insets of precious stones are commonly found in popular frame styles.

Rimless styles have become more popular as an understated way to wear eyeglasses without obvious frames. Rimless styles mainly involve attaching plastic or metal temples directly onto the lenses rather than onto a frame.

Advances in Eyeglass Lenses

You also have many options when choosing the lenses for your eyeglasses. Among the most popular types of lenses and lens options prescribed today are:

  • Aspheric lenses have a slimmer, more attractive profile than other lenses. They also eliminate that magnified, "bug-eye" look caused by some prescriptions.
  • High index lenses are made of new materials that enable the lenses to be noticeably thinner and lighter than regular plastic lenses.
  • Wavefront technology lenses are custom fabricated based on precise measurements of the way light travels through your eye, allowing for excellent clarity.
  • Polycarbonate lenses are thinner, lighter and up to 10 times more impact-resistant than regular plastic lenses. These lenses are great for safety glasses, children's eyewear, and for anyone who wants lightweight, durable lenses.
  • Photochromic lenses are sun-sensitive lenses that quickly darken in bright conditions and quickly return to a clear state in ordinary indoor lighting.
  • Polarized lenses diminish glare from flat, reflective surfaces (like water) and also reduce eye fatigue.
  • Anti-reflective coatings are among the most popular add-ons for lenses. They can dramatically improve the look and comfort of your glasses by minimizing the amount of light that reflects off the surface of your lenses, which also has the added benefit of reducing glare and thus easing eye fatigue.
  • Other lens coatings include scratch-resistant, ultraviolet treatment, and mirror coatings.

Eyeglass Lenses for Presbyopia

Presbyopia is the normal, age-related loss of near focusing ability that makes reading and other close-up tasks more difficult after age 40.

This means that the usual type of eyeglass lenses you've likely been accustomed to wearing, known as single vision lenses, no longer will work well for you.

Multifocal eyeglass lenses available for presbyopia correction include:

  • Bifocals. Lenses with two powers - one for distance and one for near - separated by a visible line.
  • Trifocals. Lenses with three powers for seeing at varying distances - near, intermediate and far - separated by two visible lines.
  • Progressive lenses. These lenses have many advantages over bifocals and trifocals because they allow the wearer to focus at many different distances, not just two or three. Because they have no lines, progressive lenses allow a smooth, comfortable transition from one distance to another.
  • Variable focus lenses. These innovative new multifocal lenses offer a larger field of view than conventional bifocals, trifocals and progressive lenses and can easily be adjusted to give you the power you need for any task.

If you see well in the distance without the need for eyeglasses, then simple reading glasses with single vision lenses may be all you need to deal with near vision problems caused by presbyopia.

The best reasons to buy Prescription Sunglasses (and it's not just to look fab)

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 eyestrain.

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 extreme wraparound styles as some nonprescription sunglasses. However, models with a lesser-curved wraparound style are available.

The Importance of protecting your eyes during fitness activities

Nowadays, sports eyewear can be spotted on almost anyone who picks up a ball, bat, racquet or stick — whether they play in the major leagues or the Little League. Fortunately, coaches, parents and players now realize that wearing protective eyewear for sports pays off. The risk of eye damage is reduced or eliminated, and the player's performance is enhanced by the fact that they see well. In fact, many clubs today do not permit their members to participate without wearing proper eye gear.

Initially, there was some resistance by children who worried about "looking funny" when they wore protective eyewear. Today, sports goggles are an accepted part of everyday life, much the way bike helmets have become the norm. In addition, both children and adults like the image that wearing protective eyewear gives them: it shows they mean business.

If You're Not Wearing Protective Eyewear, Consider This

Prevent Blindness America reports that hospital emergency rooms treat 40,000 eye injuries every year that are sports-related. Sports such as racquetball, tennis and badminton may seem relatively harmless, but they involve objects moving at 60 miles per hour or faster. During a typical game, a racquetball can travel between 60 and 200 miles per hour. Another potential danger is that the racquets themselves move at high speed in a confined space and often make contact with one another.

Flying objects aren't the only hazard. Many eye injuries come from pokes and jabs by fingers and elbows, particularly in games where players are in close contact with each other. Basketball, for example, has an extremely high rate of eye injury.

These are great reasons to wear protective eyewear, but another aspect has to do with performance. It used to be common for people with mild to moderate prescriptions to simply participate in sports without wearing their glasses or contacts. But sharp vision is a vital ingredient to performing well in nearly every sport, and participating in sports when you have less than 20/20 vision is counterproductive.

The top features to look for

Lenses in sports eyewear are usually made of polycarbonate. Since polycarbonate is such an impact-resistant lens material, it works well to protect eyes from fast-moving objects. Polycarbonate lenses also have built-in ultraviolet (UV) protection and are coated to be scratch resistant — valuable properties for outdoor sports.

Polycarbonate is the material of choice for sports lenses, but the eyewear frame plays just as important a role. Different sports require different types of frames, which has led to development of sport-specific frames. Sport frames are constructed of highly impact-resistant plastic or polycarbonate, and most come with rubber padding to cushion the frame where it comes in contact with your head and the bridge of your nose.

Some sports styles are contoured, wrapping slightly around the face. This type of goggle works well for biking, hang-gliding, and sailing. Contact lens wearers especially benefit from the wraparound style, which shields your eyes from wind and dust.

Important things to consider about Fit

Sport goggles and glasses must be properly fitted to the individual wearer. This is particularly important with children because there is a temptation to purchase a larger goggle/frame than what is needed so the youngster has "room to grow." Some growing room is acceptable, since sports goggles or frames are made to be somewhat flexible in their width adjustment. However, if the frames are oversize, they will not protect the way they were designed, leaving a potential for damage when there is impact to the head or the face. It's a risk not worth taking.