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Glasses: Frequently asked questions

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Glasses, with all of the choices in lenses and frames, it can sometimes be overwhelming.

To help you, we've compiled a list of frequently asked questions about glasses and given you the answers to put your mind at ease:

Why should I bother to go to the optometrist when I can simply pick up pair of magnifiers or ready-made glasses at the chemist?

Some people do successfully wear pharmacy reading glasses. However, you need to visit your optometrist regularly for two reasons:

  • Regular eye exams are the only way to catch "silent" eye diseases, like glaucoma, in their early stages, so they can be treated before permanent vision loss occurs. As you can't see through someone else's eyes you usually don't know something is wrong till it's too late.

  • One-size-fits-all reading glasses don't work well for people who have: astigmatism; a different prescription in each eye; or eyes that are closer together or farther apart than "average." In such cases, pre-made "readers" can cause eye strain and headaches.

What's the secret to getting glasses that look great on me?

First, decide which of the seven basic face shapes you have and read the accompanying tips about frames that go well with your shape. Then, find out which colours suit your skin, eye and hair colors.

How do I avoid annoying reflections on my glasses?

Anti-reflection coating, also known as AR coating, helps you to see through your glasses more clearly, lets others see your eyes better and eliminates the annoying white ghost images in photos taken with a flash.

I'm interested in the glasses that change to sunglasses when you go outside. Can you tell me more about them?

Glasses that change to sunglasses when you go outside are called photochromic lenses.

When exposed to the sun's UV rays, photochromic lenses darken automatically, becoming sunglasses; when no longer exposed to UV, they quickly become clear again. Photochromic lenses are a great choice if you typically wear glasses all day, frequently go outside, and don't want to carry around your prescription sunglasses.

Be aware most photochromic lenses don't darken much inside your car or SUV. This is because the windshield (and sunroof) glass used in today's vehicles blocks most of the sun's ultraviolet radiation that is required for the lens darkening process.

So, you might want to purchase a pair of prescription sunglasses for driving on sunny days.

I find most glasses to be too small for my head. Do you know of any brands that carry larger frames?

Today, most fashion eye-wear companies have introduced larger frames (including larger unisex styles), greatly expanding the options available for people who need larger frames for a comfortable fit.

You will often have better luck finding larger frames at boutique optometry practices and shops that have a large selection of high-quality frames. Discount frames are often available only in a small range of sizes, which may not fit a person with a large head.

For the greatest satisfaction with your frame selection, seek the assistance of a knowledgeable optometrist. In some cases, if you like a frame that you see in a practice but it's too small for your face, the optometrist may be able to order it for you in a larger size.

What are the warning signs that a child might need glasses?

Common signs that a child has a vision problem that requires corrective glasses include:

  • Consistently sitting too close to the TV or holding a book too close

  • Losing his or her place while reading

  • Using a finger to follow along while reading

  • Squinting and screwing their eyes up

  • Tilting their head to see better

  • Frequent eye rubbing

  • Sensitivity to light

  • Excessive tearing

  • Closing or covering one eye to read, watch TV or see better

  • Avoiding activities that require near vision, such as reading or homework, or distance vision, such as participating in sports or other recreational activities

  • Complaining of headaches or tired eyes

  • Getting lower marks at school than usual

Schedule an appointment with your optometrist if your child exhibits any of these signs.

How do I choose glasses that my child will actually wear?

The most important factor in getting a child to wear glasses is to let him or her help select them.  

When children are allowed to choose the frames that they like and feel are attractive, they are much more likely to wear the glasses

I'm worried that my son's glasses could break while he's wearing them. What's the best way to protect his eyes?

Polycarbonate lenses are recommended for children because it's very impact-resistant. Trivex is another very impact-resistant lens material that also works well for children's glasses.

How can I prolong the life of my glasses?

Follow these tips to keep your glasses in good condition:

  • If you're buying just one pair of glasses, get hard shell case and when you take your glasses off always put them in the case.

  • Don't leave your glasses on your car dashboard on a hot day

  • If you're buying glasses for a child whose prescription changes often, ask to have new lenses put in the old frames, rather than buying new frames each time.

  • Choose a style with spring hinges, which allow the temples to flex slightly outward without breaking the glasses.

  • Always ensure your lenses have an scratch-resistant coating applied.

  • Follow your eye optometrist’s instructions for the proper care of your glasses. Improper care is a primary cause of damage to anti-reflection coating and can cause other problems as well.

How often should I get a new pair of glasses?

You should get a new pair if your prescription has changed.

To keep seeing clearly, see your optometrist every two years. Your optometrist can tell you what schedule is right for you.

I can see fine with my glasses to read or drive, but I'm having trouble with certain tasks, especially at work. What's wrong?

This is a common complaint among computer users who wear bifocals (which correct only far and near vision) or reading glasses (which correct only near vision). The vision you need for tasks such as seeing your computer screen and other items within your workstation clearly is between these two extremes of far and near vision, so both bifocals and reading glasses aren't the best solution.

Progressive lenses are an improvement for people with , because these multifocal lenses provide a correction for intermediate (computer) vision as well as for distance and near vision.

However, even these lenses may be inadequate for comfortable computer vision because the intermediate zone of general-purpose progressive lenses is not located directly in the line of sight, leading to what physiotherapists call "forward head posture". This jutting forward and raising of the chin in an effort to see clearly is a source of back, shoulder and neck pain.

To reduce the risk of digital eye strain computer eyestrain or other work-related vision problems, ask your optometrist if special computer glasses (extended focus lenses) are a good choice for your needs. These lenses provide a very large field of view for reading or performing other tasks on a computer screen, eliminating eye strain, neck pain (from adopting unhealthy postures) and other symptoms of computer vision syndrome. 

Many people who try computer glasses find they are very comfortable for office work and result in far less eye fatigue throughout the day.

Be aware, however, that computer glasses are optimised for intermediate and near vision and they can't be worn for driving or other activities that require a clear distance vision.

Keep this valuable "second pair" of glasses near your computer and wear them whenever you need to perform tasks within arm's length for extended periods of time.

I'm tired of my "Coke-bottle" lenses. Is there anything I can do?

Yes — you can replace your thick, unattractive lenses with thinner, lighter high-index lenses.

For the thinnest, most attractive lenses possible, choose lenses that have an index of refraction of 1.60 or higher and are aspheric lenses. This combination of features can make your lenses up to 50 percent thinner than your current lenses — and make your glasses lighter and more comfortable, too.

And don't forget about other popular ways to escape wearing thick, unattractive glasses: contact lenses and LASIK vision correction surgery. Ask your optometrist if you are a good candidate for these options as well.

What do all those numbers on my spectacle prescription mean?

A spectacle prescription is written in a standardised format so it can be interpreted worldwide. Let's look at one and see what all the numbers mean:

Let's say the prescription for your right eye is: -2.00/ -1.00 x 180.

The first number (-2.00) indicates the spherical lens power to correct short-sightedness (myopia) or long-sightedness (hyperopia). If the number is preceded by a minus sign (as it is here), this indicates a lens power to correct short-sightedness. If the number were preceded by a plus sign (+), then the lens power would be one to correct long-sightedness.

In all cases, the unit of power for numbers in a glasses prescription is called a dioptre (D). So this prescription is calling for the correction of 2.00 D of short-sightedness.

The second number (-1.00) is the lens power (called "cylinder" power) being prescribed for the correction of astigmatism. Cylinder power in ANZ is usually preceded by a minus sign, (some eye doctors still write this with a plus sign). If you have no astigmatism correction, your optometrist might simply draw a horizontal line through this box on your prescription or write "SPH" or "DS" to indicate that only spherical power to correct short-sightedness or long-sightedness is needed.

The third number (x 180) indicates the location of what's called the "axis" of the astigmatism correction. Unlike spherical lens powers for myopia and hyperopia, cylinder powers have a different power in different directions on the lens. (Think of meridians like the spokes of a wheel.)

The axis of astigmatism is the direction where the cylinder has zero power, and it always will be a number between 1 and 180 on your prescription, preceded by an "x." If you have no astigmatism, this part of your prescription will be left blank.

If you have presbyopia and need bifocals or progressive lenses, your prescription will contain a number in a box marked "ADD". This is the additional power placed in the lower half of your lenses to assist your reading vision. It might be preceded by a "+" sign, and it typically will be a number between 0.75 and 3.00.

Finally, you may see the notations "OD" and "OS" on your prescription. These are abbreviations for Latin terms that mean "right eye" (OD) and "left eye" (OS). Sometimes, you might see a third abbreviation: "OU." This means "both eyes."

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