Archive for the ‘Eye Facts’ Category

How to Measure an Eyeglass Frame

Your prescription has changed and you need a new pair of eyeglasses.

So you take a little trip down to your local optometrist’s office. You’ve been getting your eyeglasses there ever since your first-grade teacher noticed you were squinting at what she wrote on the blackboard.

"... maybe if it was written in English? What's that... they're numbers?... oh"

You go in and look around. You check out the frames. They’ve got all the cool retro wayfarer styles everyone’s wearing. Then you look at a price tag. All of a sudden you have a bad case of sticker shock.

My eyes must be really bad, you think. That can’t say what I think it says. More than $300? Just for the frame?

You ask the optician, who confirms your worst suspicion. Not only that, he gives you a look like he’s saying, if you have to ask how much these glasses cost, you can’t afford them.

That’s it, you say to yourself, after slinking out of there with your hand on your wallet. I’ve had it with these brick-and-mortar eyeglasses stores, where the price gouging feels more like eye gouging. I’m finally going to do it. I’m going to order glasses online, and save all that money I’ve been hearing about.

Congratulations!

You’ve just made a decision worth hundreds of dollars. Maybe even thousands in the long run. It’s true. If you shop carefully online, you’ll find prices for discount eyeglass frames and lenses so low you could buy high-quality, stylish eyeglasses for your whole family online for what it would cost to buy just one pair for you locally.

Subtle... am I right?

But there’s a major pitfall to avoid when you order glasses online.

How can you make sure the glasses you buy over the internet will fit you if you can’t try them on before you buy them?

That’s a great question. We have an even better answer.

Here is how to make sure the glasses you buy online will fit you well when they come in the mail, and you take them out of the package and try them on.

First, if you already have a pair of eyeglasses that fits you well and looks good on your face, you’re ahead of the game.

All you have to do is get the frame dimensions from these eyeglasses, and order a pair online that matches those dimensions.

It doesn’t even have to be an exact match. All eyeglass frame dimensions are listed in millimeters. A millimeter is a tiny unit of measurement. There are 25.4 millimeters to an inch. So you have a leeway of a few millimeters on each element of a frame.

Those elements are:

The bridge. This is the part of the frame that goes across the bridge of your nose. That’s why it’s called the bridge.

The temple arm. Those are the parts that connect to the front of the frame on either side of your head and rest behind your ear. Sometimes people call the temple arms “legs,” “stems,” or even “bows,” but in the optical industry they’re called temple arms, because they are next to your temple.

The lens width. This is the diameter of one lens, measured at the widest part. It’s also called the “eye size” in the optical industry, which doesn’t make a lot of sense, because it’s not the measurement of the size of your eye; it’s the measurement of the width of your eyeglasses’ lens. We’re mentioning this because sometimes eye doctors will suggest frame dimensions and write these on your prescription. When they do, they may write “eye size” on the prescription when they mean the lens width. So don’t worry about matching that number with the size of your eye. It’s the width of one eyeglass lens.

The lens height. This is measured just like the lens width, but vertically, not horizontally. If your prescription includes an NV-ADD (Near-Vision reading ADDition) number, you can order bifocal or progressive glasses. This is where the lens height measurement becomes crucial: The lens height must be at least 30 millimeters to accommodate a bifocal or progressive prescription.

The frame width. This is the most important measurement on a frame to determine whether it will fit you well and look good on your face. It’s the measurement of the entire front of the frame, from the point that sticks out farthest on the left, to the point that sticks out farthest on the right. Or vice versa.

Remember when we said that if you have a pair of glasses right now that fits you well and looks good on your face you are ahead of the game? Well, you’re rounding third and heading for home if on the inside of one of your temple arms you have three numbers, which are the dimensions of, in order, the lens width, the bridge, and the temple length.

Most of the time, if the numbers are stamped on the inside of the temple arm, they will be listed the way they are in the first example, on the left.  (Ignore the first number on the temple arm that precedes these numbers; that will just be the manufacturer’s model or stock number.)

After this model or stock number, the lens width comes first, the bridge is next, and the temple arm is last. Sometimes it could be listed the way it is in the second example, on the right, with the temple arm length first, the lens width next, and the bridge last. Either way, there will usually be a little square between the first and second numbers.

You may even see a pair of glasses that has these numbers stamped or engraved on the inside of the bridge, but this is rare.

If you have the numbers stamped on the inside of the temple arm or on another element of the frame, the only other measurements you need are the frame width and the lens height.

If you don’t have numbers stamped on the inside of the temple arm, you can measure the dimensions of your frame elements with a millimeter ruler. Don’t have a millimeter ruler? Not a problem; you can get one at any drug or dollar store. However, if you have a cloth tape measure with millimeter hash marks, this would be the best measuring tool to use, especially when we come to the temple arm measurement.

Here’s how to measure each element we discussed:

The bridge. Measure horizontally, at the top of the bridge, from the edge of one lens to the edge of the other lens. The part of the frame that holds the lenses in place will be included in the measurement, since you’re measuring from lens edge to lens edge, not frame edge to frame edge.

The temple arm. This is the measurement for which a cloth measuring tape with millimeter hash marks would come in handy. Here’s why: The temple arm is measured from the hinge – where the temple arm connects to the front of the frame – all the way back to the tip.

The measurement includes the bend around the ear, which is why a cloth tape measure is useful for this measurement. If you have a cloth tape measure, you can measure the curve easily. If you’re using a plastic or wood straight-edged ruler, it would be best to do the measurement in two parts.

Start at the hinge, measure to the beginning of the bend, and write that measurement down. Then go back to where you left off, right at the beginning of the bend. Measure the last part, which is angled, to the tip. Add the two sectional measurements together, and that’s the total temple arm length.

You may have a pair of glasses with cable temple arms, the kind that curve around your ear. (pictured above)

If you don’t have a cloth millimeter tape measure, you could print out the downloadable PD ruler at the Zenni Optical website, www.zennioptical.com:

Click here for a larger image

You can use this paper ruler to measure the cable temple arm. Or you could cut a strip of paper about a half-inch wide and 10 inches long. Mark the little paper strip where you begin measuring the temple arm at the hinge. Curve the paper strip around the curve of the temple arm and mark it where the temple arm ends. Stretch out the paper strip and measure the length with a millimeter ruler. That’s your cable temple arm length.

The frame width. Again, it’s the entire horizontal measurement of the front of the frame, measured from the part that extends farthest outward on one side to the part that extends farthest outward on the other side. A metal frame may have a little piece that sticks out on the side toward the top, like the part that extends from the outer edge of the lens on a pair of rimless glasses, just before bending to meet the hinge of the temple arm, such as on this rimless frame:

If you do have a frame such as this one, or any frame with a piece that sticks out on the side, you would include that part of the frame, on each side, in your measurement of the frame width. Whether a frame is too big, too small, or just right for your face is mostly determined by the frame width. Also, make sure you do this measurement at the front of the frame. You don’t need to measure the distance between the two temple arms at the back of the frame.

The lens width. If the width of the frame you are shopping for online matches within two or three millimeters the width of the frame you have that fits you well, you can be confident that the frame you see online will fit you just as well. But be aware of the lens width: even though the total frame width might match the width of your frame, the lens width might be a little narrow or wide for your pupillary distance, which is the measurement of the distance between the middle of each pupil. This measurement determines where to place the optical center on each lens.

The lens height. This is measured just like the lens width, but vertically, not horizontally. Once again, the lens height must be at least 30 millimeters to accommodate a bifocal or progressive prescription. In addition, pay attention to the lens height, because this is an important factor in determining how the glasses will look on your face. If you get a frame with a tall lens height, something over 36 millimeters, the glasses may look too big for your face. Conversely, a too-short lens height, lower than 30 millimeters, may not provide all the corrected-vision coverage your eyes need.

Once you have the measurements of your frame, you can shop for a frame online that will fit you.

Remember, you have a leeway of a few millimeters on each element, with a caveat: Stick to no more than two millimeters higher or lower on the bridge. For example, if your perfect bridge measurement is 18 millimeters, you can go as low as two below that, 16 millimeters, or as high as two above, 20 millimeters. Therefore, a bridge that’s anywhere between 16-20 millimeters should fit you just fine.

Also, if you’re getting a frame with adjustable nose pads, this gives you even more leeway, because the nose pads can be adjusted for the best fit. Pinch them closer together to make the bridge fit more snugly and rest higher on your nose; spread them apart to loosen the fit and let them rest lower on your nose.

On the frame width, lens width, and lens height, you should be fine with a leeway of three millimeters. Therefore, if your perfect frame is 135 millimeters wide, frames between 132-138 millimeters should fit you just as well.

Since many temple arms are adjustable at the curve where the temple arm bends behind your ear, you have a leeway of as many as four millimeters. In that case, if the temple arm on your eyeglasses is 140 millimeters, you will be fine with a temple arm that falls between 136-144 millimeters. However, many temple arms are not adjustable, especially those made of aluminum alloy, titanium, memory titanium, and memory plastic. Check the temple arm material listed in the description of the frame to be sure. Also, look at an enlarged picture of the online glasses. If you can see that embedded in the temple arm is a stainless steel rod, you can be confident that this frame’s temple arm is adjustable.

Here are a few more things to keep in mind. The vintage styles from 50 years ago and more that are popular today were often worn much smaller than glasses are today. This is because lenses were made of glass then, and the heaviness of glass caused eyeglasses manufacturers to keep the lenses as small as possible.

Conversely, eyeglasses in the ’70s were frequently oversized, such as these worn by the late Hollywood super-agent Irving Paul Lazar:

When you're an ex-president's literary agent you can pretty much wear whatever you want.

Another thing to keep in mind is how strong your prescription is. If you have a strong prescription, +/- 6.00, the wider and thicker your lenses will be, on the outer edge with a minus sphere (nearsighted) prescription, in the middle with a plus sphere (farsighted) prescription. Therefore, if you have a strong prescription you may want to stick with lens widths that are lower than 50 millimeters.

Good luck!

Friday, December, 6 2013 by

Nutrition and Vision

Forget that tired old question about who’s hotter, Ginger or Mary Ann.

We’ve got a tougher one: Who has better eyesight, Popeye or Bugs Bunny? Before you hop in with an answer, let’s consider the qualities of these two animation icons.

In this corner, weighing 150 pounds (and that’s just his forearms), is everybody’s favorite sailorman. Look at him nuzzle his anorexic extra-virgin girlfriend and inhale his spinach right from the can.

In that corner, weighing oh, probably 20 pounds (and that’s just his ears), is Elmer Fudd’s favorite nemesis. Look at him nonchalantly lean on the ropes while he chomps on a fresh carrot.

So who’s it going to be? The perpetually squinting Bluto-battler or the Cwazy Wabbit? Amazingly, the winner by a knockout is Popeye!
 

 
Spinach before carrots? How can that be? Didn’t our moms tell us to eat our carrots because they’re good for our eyes?

Yes they did. But they also told us that if we keep crossing our eyes, one day they’re going to get stuck that way. We love our moms, but maybe they’re not the most reliable source of information when it comes to eyes.

Nope, the consensus is in from nutrition and vision experts: the nutrients in spinach are actually better for the health of your eyes than the ones in carrots.

Let’s look, with both eyes open, at some facts surrounding nutrition and vision.

These facts come courtesy of the Age-Related Eye Disease Study (AREDS) and its follow-up, AREDS-2, both conducted by the National Eye Institute (NEI), which is part of the United States’ National Institutes of Health (NIH).

Keep track of those acronyms. There will be a test later. Not.

Results from AREDS, begun in 1992, were published in 2001. Results from AREDS2, begun in 2006, were published this year. Each study examined the two most common forms of eye disease, age-related macular degeneration (AMD) and cataracts.

What are those, exactly? Let’s start with macular degeneration.

The macula is part of the eye’s retina, which serves a similar function to the film in a camera. We should probably explain that before there were digital cameras there was this thing called film. Google it.
 

 
Just like a camera lens, the eye’s lens receives an image. The image is transmitted to the retina, like the way an image taken by a camera lens used to be transmitted to the film in the camera.

The macula is in the center of the retina. When light comes to a point of focus on the center of the macula, you can see objects and colors sharply.

The macula is yellow, which enables it to absorb harmful blue and ultraviolet light that enters the eye, blocking this harmful light like a pair of sunglasses.

AMD comes two ways: dry and wet. Dry is when the tissue of the macula deteriorates. Wet is worse – that’s when the blood vessels behind the retina leak blood and other fluid into the macula.

AMD is the leading cause of blindness in the U.S. of people over 60, according to research conducted under the auspices of Johns Hopkins Medicine. Some estimates put the number of affected people as high as 15 million. However, many of those people are only mildly affected or won’t experience a decline in vision at all. But about 2 million Americans with AMD are severely affected, to the point of acute vision loss.

Check out this picture, which you can look at to test to see if you have any form of macular degeneration:
 

 
Click here for the full grid and explanation
 
Now let’s examine cataracts.

Cataracts form when the eye’s lens becomes cloudy, leading to blurred vision and vision loss. Cataracts happen because the lens of the eye is made up mostly of water and protein. As we age, the protein begins to clump together, creating the cloudy effect on the lens.

Most cataracts are related to aging and are very common in older people. By age 80, more than half of all Americans either have a cataract or have had cataract-removal surgery, according to statistics compiled by the American Academy of Ophthalmology (AAO). In addition, almost 22 million Americans have cataracts in at least one eye, and the number is expected to increase to 30 million by 2020.

OK, so now that we know what AMD and cataracts are, let’s look at which nutrients AREDS and AREDS2 found helpful in addressing these eye diseases.

The first study, AREDS, examined whether taking vitamins E and C, zinc, and beta-carotene – which makes carrots orange – reduced the onset of these diseases.

For AREDS2, the NEI scientists added omega-3 fatty acids and the antioxidants lutein (pronounced LOO-teen) and zeaxanthin (zee-ah-ZAN-thin) – both of which are abundant in spinach, kale, and other leafy green vegetables. Both of these antioxidants are also present in the macula.

In addition to being antioxidants – which are molecules that help maintain the health of cells – lutein and zeaxanthin are carotenoids. Carotenoids are what give plant foods their colors.

Lutein is especially important because it gives the macula its yellow pigment. When this pigment degenerates – causes of this degeneration include aging, a poor diet, smoking, being a female, and having blue eyes – the macula degenerates, too, because the protection the pigment supplies gets lost. It’s like a dark, polarized sunglass lens getting replaced by a clear lens on a bright, sunny day.

Now let’s go back to the studies and their findings.

Contrary to the preliminary results of AREDS, the AREDS2 results show that taking vitamins E and C, beta-carotene, zinc, and the omega-3s had no effect on decreasing the onset or reducing the effects of either disease.

However, there were significant reductions in AMD from lutein and zeaxanthin.

Moreover, when beta-carotene was removed from the study, the scientists found that the AMD-reducing effects provided by lutein and zeaxanthin doubled.

Sorry, Mom. Sorry, Bugs.

AREDS2 also found that neither lutein nor zeaxanthin prevented cataracts from forming. But that’s not to say that there are not foods that help prevent cataracts. A 1993-2009 study conducted by researchers at the University of Oxford in England found that vegetarians and vegans were less likely than meat eaters to develop cataracts – vegetarians 30 percent less likely, vegans 40 percent– and that the more meat people ate, the greater the likelihood they would develop cataracts.

But let’s say you’re a young whippersnapper who hates carrots and spinach. You are years away from getting cataracts, and you spend more time thinking about getting MDMA than AMD.

"It's Good for You... you should probably eat it"

We can hear you now:

“Dude. Why should I care about this? My vision’s 20/20. I’m sticking with the four major non-food groups – doughnuts, candy bars, 64-ounce sodas, and cigarettes!”

Go ahead, knock yourself out. But remember Dud, uh, Dude, what you eat now affects your eyes today and in the future.

Keep eating junk food and smoking cigarettes, and you could be setting yourself up for type 2 diabetes. Almost 400 million people around the world have diabetes, and 25 million of them are Americans, according to the American Diabetes Association (ADA). Close to half of all American diabetics have some form of diabetic retinopathy, which, after macular degeneration, is the second leading cause of blindness of people in the U.S. Also, people with diabetes get cataracts earlier, and diabetics are 60 percent likelier to get cataracts than non-diabetics, the ADA states.

Type 2 diabetes used to be known as adult-onset diabetes, but the number of children and adolescents who have this type of diabetes has greatly increased during the past 20 years. Consequently, the name of the disease has changed to reflect this appalling reality.

But if you eat a diet rich in – you know what’s coming – fruits and vegetables, that will not only improve your chances of maintaining good vision but improve your overall health, too.

And that’s what’s up, doc.

Eye Diagram Via: Wiki Media Commons

Monday, November, 25 2013 by

Polarized Sunglasses, What Exactly Are They?

wearing polarized sunglasses, Zenni optical

You’ve probably seen drugstore sunglasses labeled “polarized.” Maybe you looked at those next to sunglasses that weren’t polarized, and wondered what the difference was. Or maybe your eye dr. recommended getting polarized lenses, but you weren’t sure how they worked and what benefit they offered.

Well, we’re going to tell you! Very simply, here’s what polarized lenses do: they reduce glare by blocking horizontal light rays.

Why horizontal? Here’s a little background on how polarization works: light comes from the sun in all directions, and it is reflected in every direction, too. When it reflects from light-colored horizontal surfaces – such as a white sidewalk, a white-sand beach, snow, or sunlight reflecting on water – it is said to be polarized horizontally. Light that is polarized horizontally is responsible for most of the glare that interferes with our vision.

How do polarized lenses work? To understand this, it’s useful to think of window blinds. Let’s start with Venetian blinds, which are horizontal. When Venetian blinds are open, light comes into the room in horizontal stripes, depending on the angle of the sun and the angle the blinds are open.

Polarized lenses are more like vertical blinds. When vertical blinds are open at a certain angle, light comes into the room in vertical stripes. Since horizontally reflected light is responsible for most of the glare we see, the polarized tint is placed on the sunglass lens in vertically angled strips. These vertical strips of tint allow vertically reflected light into the eye but block horizontally reflected light – greatly reducing horizontally polarized glare.

Most polarized lenses are sunglasses. Polarized sunglasses are especially popular with boaters, since water is a very reflective surface on a sunny day. Polarized sunglasses are also great for other outdoor activities, such as golfing and tennis, since they can help to sharpen the focus on the ball. They can also be good for driving, since polarized lenses reduce the glare that reflects from the shiny hood of a car, or the glare from the surface of the road on a hot, sunny day.

However, in some situations there can be drawbacks to polarized lenses. They can be problematic for skiing, since blocking the reflected glare off an icy patch might prevent the skier from noticing and steering away from a potential hazard.

In addition, it can sometimes be difficult to read liquid crystal display (LCD) or light-emitting diode (LED) screens on a boat or plane’s instrument panel while wearing polarized sunglasses. This could interfere with the pilot’s ability to clearly read and quickly respond to the information on the instrument panel. This could also apply to the global positioning system (GPS) and other displays of a car’s dashboard, a smart-phone, an ATM, or a self-service gas pump.

An oddity you may notice while wearing polarized sunglasses is that when you look at your car’s rear or side window from the outside, or perhaps the windows on an office building, you may see splotchy, iridescent spots. When you remove your polarized sunglasses, these spots are invisible.

This effect is created because you are looking at heat-tempered glass. The heat-tempering creates several stress points on the glass, enabling the glass, when broken, to crumble into small, granular chunks, which are safer than splitting the glass into sharp, jagged shards. The stress points also reflect the light in different directions from the parts of the glass that don’t have these stress points. The stress points prevent the polarized lens from filtering out the light evenly across the surface of the glass, creating the splotchy, iridescent effect.

If you are unsure if your sunglasses are polarized, here’s a fun, simple test to see if they are. Hold your sunglasses up to a computer screen, which has an anti-glare coating similar to the anti-glare coating on a polarized lens. Angle your sunglasses about 60 degrees, with one side of the frame at 10 o’clock and the other at 4 o’clock. If the lenses are polarized, they will turn black.

You could also take the test with two pairs of polarized sunglasses – hold one pair at a horizontal (180-degree) angle. Now hold the other pair in front of the first pair, but rotate this second pair of sunglasses a half-turn, till it’s straight up and down, at a vertical (90-degree) angle. You will see that the lenses of both pairs of sunglasses turn considerably darker where the two lenses overlap when they are perpendicular. This is because when you angle one polarized lens to another perpendicularly, they block glare both horizontally (the horizontal pair) and vertically (the vertical pair).

At Zenni Optical, we offer polarized sunglasses in our 1.50 and 1.59 index single-vision and progressive (no-line bifocal) lenses, and in our 1.49 index bifocal lens. All of our detachable sun shades, whether magnetic or clip on, whether standard (the same tint color and shade all the way through) or gradient (the tint is darker at the top, getting progressively lighter toward the bottom) are polarized.

A101204 Sunglasses, Zenni Optical

A note of caution regarding drugstore sunglasses that are not polarized. If the lens is a non-polarized, darkly tinted lens not treated to block UV rays, it could be more dangerous to the eye than wearing clear, un-tinted glasses that have 100-percent UV protection. This is because the dark tint could cause the pupil to dilate, allowing more harmful UV rays into the eye.

You can rest assured that on every pair of glasses Zenni Optical makes, tinted or clear, we include a 100-percent UV-protection coating – for free.

In addition to polarized sunglasses, Zenni Optical also offers a different kind of sunglass lens that sometimes people confuse with polarized: photochromic lenses, which turn dark in the bright sunlight and become clear again in the shade or indoors.

Although you may have heard about a new technology that adds polarization to photochromic lenses, Zenni Optical does not offer these lenses at this time. Our polarized lenses are permanently tinted sunglasses that greatly reduce glare.

Friday, November, 15 2013 by

Just Exactly What is Astigmatism?

If your prescription (Rx) has a correction in the Cylinder (CYL) and AXIS sections, this means you have an astigmatism.

If you have an astigmatism correction on your Rx – and the vast majority of eyeglasses wearers do – you may be experiencing one or more of these symptoms when you are not wearing corrective lenses:

  • Blurry vision
  • Double vision
  • Having to squint to see near and far
  • Difficulty focusing on printed words
  • Eye strain
  • Tired eyes
  • Headaches

What causes an astigmatism? It’s predominantly genetic, and it’s usually present to some degree at birth. It may increase or decrease with age. Someone may also develop an astigmatism following an injury to the eye, eye disease, or eye surgery.

An astigmatism results when one or both of the two parts of the eye that bring images into focus – the cornea and the lens – are aspheric. This means that they are not perfectly round and smooth spheres, like a ping pong ball.

An aspheric cornea or lens is more like the oblong shape of a football.

When the cornea and lens are round and smooth, they focus light directly onto the middle of the retina, at the back of the eye, making what you see look crisp and clear. In this case, your cornea and lens are perfectly spherical.

You don’t have an astigmatism if it says “SPH,” meaning “spherical,” on your Rx in the CYL section. Writing “SPH” in the CYL section is one of the ways an eye dr. indicates that the cornea and lens are perfectly round – spherical – and that no astigmatism is present. It’s not uncommon to have an astigmatism in one eye but not in the other.

Another abbreviation for “no astigmatism present” is DS, short for the Latin phrase diopter simplex, which means “unaffected,” indicating that this eye is unaffected by an astigmatism.

But let’s say you have an astigmatism correction on your Rx. If so, you will see a minus or plus number in the CYL section of your Rx.

If the CYL number is preceded by a minus, this means that the aspheric cornea or lens causes light to come to a focus point in front of the retina. It stops at a place that’s too near – not far enough to reach the retina – for you to see well. If the CYL number is preceded by a plus, this means that the aspheric cornea or lens causes light to come to a focus point behind the retina. It stops at a place that’s too far – not near enough to reach the retina – for you to see well.

Each type of astigmatism is corrected by the number in the CYL, which is literally a cylinder placed on your lens, which would be a convex (curved outward) cylinder if the Rx calls for a plus CYL, or a concave (curved inward) cylinder if the Rx calls for a minus CYL.

You will also see a whole number, somewhere between 1 and 180, in the AXIS section. If you have a plus or minus number for the CYL but nothing written in the AXIS field, call your eye dr.’s office. There must be an AXIS if there is a CYL.

Here’s why: the AXIS is literally the degree of angle at which the cylinder is placed on the lens.

For example: if the AXIS number is 180, the astigmatism is corrected by placing the cylinder horizontally on the lens. If the AXIS number is 90, the astigmatism is corrected by placing the cylinder vertically on the lens.

Sometimes the eye dr. will write the AXIS number with one or more zeros before the actual AXIS number, such as 005 or 090. Those preceding zeros are just placeholder digits and the actual AXIS number is 5 or 90. The preceding zeros won’t show up on the AXIS drop-down window on the Your Prescription page where you enter your Rx numbers. You can ignore those zeros.

Every Rx lens Zenni Optical offers can accommodate an astigmatism correction. A strong astigmatism correction would be one that has a number in the CYL category between 2.50 and 6.00, plus or minus on the Rx. The highest CYL number we can correct is plus or minus 6.00, and most of the lenses we offer can accommodate this CYL correction.

Because correcting a strong astigmatism is more complicated than correcting a mild astigmatism, an extra-strength charge is assessed on orders of glasses with single-vision lenses when the Rx indicates a strong astigmatism. Bifocal or progressive lenses with high CYL numbers that call for strong astigmatism corrections come with no extra-strength charge.

image via: Taking Care Of Your Eyes Is Easy | Kowa Optimed Eye Care

Tuesday, November, 5 2013 by

Treating Trachoma in the Developing World

blind indigenous
 
I recently read a column by journalist Nicholas Kristof about efforts to treat and eliminate several devastating and deadly diseases within the developing world. While I was familiar with some of these diseases, such as polio and leprosy, he also mentioned trachoma, a devastating eye disease of which I had never heard. When I read the article, I was not only shocked to learn of the disease’s existence, but also the importance of helping developing nations prevent and treat the disease before it claims its victim’s eyesight.

Trachoma: A Leading Preventable Cause of Blindness

 
As the World Health Organization explains, Trachoma is an eye disease caused by a bacteria called chlamydia trachomatis, which is spread through contact with contaminated water and infected flies, as well as person-to-person contact. If left untreated, the condition can eventually cause a malformation of the eyelid, which leads to cornea damage as a sufferer’s eyelashes repeatedly scratch the eye. The condition is not only painful, but can cause permanent blindness. Losing one’s eyesight is bad no matter where it happens, but for those living in the developing world, vision loss is particularly devastating, as there are often few social, educational or medical resources for the blind.

Tragically, the suffering caused by trachoma is preventable, but prevention depends on a number of factors, including access to education, clean water, and medical care. Programs in the developing world concentrate on improving hygiene standards and access to clean water while also providing proper diagnosis of the condition while it can still be treated with antibiotic medication. Once the disease has progressed to the point that the eyelid is deformed, surgery (with an 80%) can be performed by trained nurses. According to Helen Keller International, this cost of this surgery starts at only $40.

 

How You Can Help

 
If you are interested in helping to fight trachoma, consider making a donation to or volunteering for an organization that provides eye health care and education services in the developing world. Another option is to work with a charity that helps the developing world gain access to clean water supplies. Whichever option you choose, your help can help save people from horrific and completely unnecessary suffering

 

Monday, October, 7 2013 by