Archive for the ‘Eye Frames Online’ Category

Which is the Best Place to Get Reading Glasses? Zenni or the 99¢ Store?

Everybody knows you can get reading glasses at the dollar store for a dollar.

 

dollar bill
Heck, if you’re a real bargain shopper you might even want to save a penny.

 


In that case, you can get them at the 99₵ store for 99₵.

 

dollar store

Yes, there are exactly 99 pennies in this picture. We know because we counted. How fitting that the 99₵ store is where the couple known as Speidi (remember them?) appears to have ended up.

 

Just Jared
So if you can get reading glasses for a buck or for a penny less, why should you get them from Zenni, where they would cost at least $6.95?

confused lady

Because the $6.95 reading glasses you can get from Zenni are more than seven times better than the reading glasses you can get from the dollar or 99₵ store.

 

A lot more.
 
Buying reading glasses at the dollar or 99₵ store might be penny wise.

 

Penny Wise

But it’s pound foolish.

 


 
Here’s why.
 
The reading glasses you get at the dollar or 99₵ store don’t have:
 
Your exact prescription.

 


 
Your exact pupillary distance (PD).
 

Download this PD ruler if the eye doctor or optician won’t give it to you, and you can measure it yourself.
 
Your exact frame size.

 


 

Anti-reflective (AR) coating.

 


 
OK, if you get AR coating, they’re going to cost a little more, but it’ll be worth it. AR coating greatly reduces glare from external light sources as well as reducing eyestrain from long sessions on a computer.
 
See The Zenni Blog to read the AR coating blog post (“Don’t Fear Mothra – Her Eyes Inspired Your Glasses’ Anti-Reflective Coating”) for a fuller discussion of the benefits of AR coating.
 
A 10% pink tint on the lenses will help reduce eyestrain, too.

 

 
 
Now let’s break down all these categories – prescription, PD, frame size, AR coating, and tint – and examine how getting a pair of reading glasses made to order at Zenni is better in all of these respects than buying a pair at the drug, dollar, or 99₵ store.

 


 

Get outta here, you two! Your 15 minutes of fame were up 20 minutes ago.

 
Prescription:
You can’t enter your exact prescription in the reading glasses you buy off the shelf. They will have the same magnification in each lens. But most people have different prescriptions for each eye. Again:

 


 

See how the OD (right eye) has +3.00 and the OS (left eye) has +2.75? You won’t be able to customize off-the-shelf glasses accordingly, unless you buy a +3.00 pair and a +2.75 pair, and switch the lenses yourself, assuming that you can get the lens out of one frame and into the other, and make it stay there without breaking a lens or the frame.

 

Broken Glasses

 

At Zenni, you can enter your exact magnification for each eye.

 
In addition, your prescription may call for an astigmatism correction (that’s when the prescription has Cylinder and Axis numbers).

 

You won’t be able to get this on a pair of drug, dollar, or 99₵ store readers, because those eyeglasses don’t have astigmatism corrections. Consequently, everything you see will be blurry, either a little or a lot, depending on your astigmatism.

 

At Zenni, you can enter your exact Cylinder and Axis numbers to correct your astigmatism.
 
PD:
Your pupillary distance (PD) is crucial when ordering prescription eyewear, including reading magnification eyeglasses.

 

 

That’s pupillary distance, not puppy-lary distance!

 
The PD is the measurement from the center of one pupil to the other. The PD determines where the optical center should be placed on each lens. The reading-vision optical center should be right in front of your pupils when you read.

 

But your PD won’t be accommodated by a pair of off-the-shelf reading glasses. You won’t even know what the PD is, because there’s no indication of the PD on reading glasses you get at the drug, dollar, or 99₵ store.
 
The reading glasses you get off the shelf will have an average PD on the lenses, based on the size of the frame.
 

Reading Glasses

 
If you’re looking through a pair of reading glasses that has a wider or narrower PD than yours, it will hamper your ability to see well with the glasses. You may get headaches and eyestrain, too.
 


 

At Zenni, you select a frame that accommodates your PD. When we make the glasses, we use your PD to determine the placement of the optical center on each lens, giving you the clearest, crispest vision.
 
Frame size:
The comedian Alan King had a saying about the difference between what the English call “bespoke” (custom-made) suits and those that are purchased off the rack.

 


King would say, “If it’s off the neck, it’s off the rack.”
 
The same principle applies with eyeglass frames. You take your chances with frames you pull off the rack at the drug, dollar, or 99₵ store. You may not find one in a style you like, or one that fits you well.

 

At Zenni, you can select a frame in the size – not to mention style – that suits you.
 
AR (anti-reflective) coating:
Store-bought reading glasses don’t have AR coating. Glasses at Zenni do. It’s a great extra to order for reading or computer glasses, because it reduces glare. Again, everything you need to know about AR coating is right here.
 

Don’t Fear Mothra – Her Eyes Inspired Your Glasses’ Anti-Reflective Coating

 
Tint:
You’re not going to find reading glasses at the drug, dollar, or 99₵ store that have a 10% pink tint on the lenses. If you’re going to spend a lot of time reading on a computer screen, this tint percentage and color would be a good feature to have, since it’s restful and helps reduce eyestrain. It’s just $4.95 at Zenni.
 
This completes our examination of the relative merits of store-bought reading glasses and Zenni-bought reading glasses.
 
Let’s review. Store-bought reading glasses don’t have your exact prescription, PD, frame size, AR coating, and 10% pink tint.
 
Zenni glasses do. Not much of a contest, is it? It’s hard to build suspense when the results are so lopsided, but … the envelope, please:

 

You, with a pair of customized Zenni reading glasses that include your prescription, PD, frame size, AR coating, and 10% pink tint. Best of all, these two won’t be in line ahead of you.
 

Tuesday, March, 25 2014 by

Don’t Fear Mothra – Her Eyes Inspired Your Glasses’ Anti-Reflective Coating

If you like the way the anti-reflective (AR) coating on your eyeglasses reduces glare, you can thank Mothra – or a real-life moth – for that.

Godzilla vs. Mothra | Zenni Optical

That’s because moths’ eyes are covered with a special film that eliminates reflections. This is necessary because of their well-known attraction to flames.

RuPaul | Zenni Optical

No, not that kind of flame! This kind:

A moth to a flame | Zenni Optical

If moths’ eyes reflected light, it would alert predators to their presence. But moths’ eyes are coated with a super-thin film structured in a hexagonal pattern of bumps that are so tiny they are smaller than the wavelength of visible light. These bumps reduce reflections from flames or other light sources by matching the wavelength of visible light, which blocks the light’s reflections.

Moth eye does not reflect light | Zenni Optical

AR coatings on eyeglasses take their cue from the eyes of moths. They work in a similar way, using a super-thin layer of metal oxide to reduce reflection by matching a reflected wave of light with an equal and opposite “incident wave” (roughly oversimplified, an interfering wave), which causes the two waves to cancel each other out.

Reflective light diagram | Zenni Optical

You don’t have to be a scientist, or even an accomplished graph reader, to see that the red wave of the reflection is equally matched by the black incident wave of the AR coating, which blocks the reflection on the lens as effectively as Jerry Kramer blocked Jethro Pugh in the Ice Bowl. (What? Ask a football fan or Google it.)

Jerry Kramer Ice Bowl Block | Zenni Optical

AR coatings are highly recommended for eyeglasses. They’re especially useful with high-index prescription lenses, because high-index lenses are thinner, lighter, and flatter than standard- and mid-index lenses, and therefore tend to reflect more light than lower index lenses do.

Before and After Anti-Reflective Coating for Glasses | Zenni Optical

But all lenses, even non-prescription lenses, benefit from AR coating, especially sunglasses.

Sunglasses with anti-reflective coating | Zenni Optical

However, one of the most important uses of AR coating will not involve sunglasses, unless you’re this guy.

Corey Hart in Sunglasses | Zenni Optical

For most people, who, unlike Corey Hart, don’t wear their sunglasses at night, AR coating is a must-have for driving glasses, prescription or non-prescription sunglasses, or clear prescription lenses. AR coating is great for reducing glare from streetlights, stoplights, taillights, and oncoming headlights. It’s especially good at decreasing the “halo” effect.

Model dressed as an angel with a halo | Zenni Optical

Wait, not that halo effect – that one should only be increased! Multiplied, even, at every possible opportunity. Here is the halo effect you want to reduce:

Halo effect | Zenni Optical

AR coating has daytime and indoor uses, too. It’s great for people who spend a lot of time on the computer, since it reduces glare from the monitor, which can cause eyestrain.

A woman who needs protection from glare | Zenni Optical

AR coating performs a great cosmetic function, too. It greatly decreases the reflection on eyeglasses’ lenses from external indoor and outdoor light sources. With AR coating, people looking at you while you’re wearing glasses will see your eyes rather than what’s reflected on the lenses. This is an excellent feature to have, unless you’re acting in Alfred Hitchcock’s Strangers on a Train.

Strangers on a Train still - Glasses with glare | Zenni Optical

If you haven’t seen that movie, check it out. It’s one of Hitchcock’s best.
 
In a minute we’re going to examine the three main types of AR coatings available for eyeglasses’ lenses: standard, hydrophobic, and oleophobic. They all work the same way, by blocking reflection and reducing glare with one or more layers of metal oxide that (remember the moth) allow more light to pass through the lens.

Before & after glasses anti-glare | Zenni Optical

But first, let’s dispose of the most common misconception about AR coatings: that they tint the lens. This is not true. AR coatings are clear and colorless and invisible on the lens.

Zenni Optical Eye Glasses with invisible AR coating

But there is a color-based way to tell if your lenses have AR coating. Sometimes people will think that, because reflections on the lenses are not entirely eliminated, their glasses don’t have AR coating, even though they ordered it.
 
To see if your eyeglasses have AR coating, hold the glasses parallel to the ground, with the temple arms (the stems that go behind your ear) up or down. Angle the glasses so you can see reflections on the lenses. If the reflections look green or purple, your lenses have AR coating.

High power lenses | Zenni Optical

Here’s why: The reflections will look green or purple, or both green and purple, because AR coating blocks waves that are in the green-to-purple wavelength of the spectrum of visible light. That’s why these colors are reflected on the lenses. If that’s not confusing enough, here’s a chart that will really have you scratching your head, unless you’re an optics geek:

Optics diagram for antireflective coating | Zenni Optical

Now that your brain has recovered (we hope), let’s look at those three main types of AR coatings: standard, hydrophobic, and oleophobic. Standard AR coating, which is $4.95 at Zenni Optical, and which can cost north of $100 at other optical retailers, does a great job of reducing reflections on eyeglasses lenses.
 
But there’s a big difference between standard AR coating and hydrophobic, which is $8.95 at Zenni, and oleophobic, which is $14.95 at Zenni. These AR coatings can cost as much as $200 at other optical retailers.
 
The hydrophobic AR coating is called that because although it blocks reflections the same way the standard AR coating does, it’s also water (hydro) resistant (phobic). It puts a slick surface on the lens that resists the buildup of water-based moisture, which is important to have when you’re watching a tearjerker like The Best Man Holiday for the 87th time.

The hydrophobic and oleophobic AR coatings make your eyeglasses’ lenses easier to clean than lenses with the standard AR coating. You can do this experiment yourself. If you have a pair of glasses with standard AR coating and a pair with hydrophobic or oleophobic AR coating, clean each pair with the cloth that comes with your Zenni glasses. It’s much easier to clean the hydrophobic or oleophobic pair than the standard pair, right? The cloth slides right across the surface of the hydrophobic- or oleophobic-coated lenses, while on the pair with the standard AR coating there’s a little drag on the lens.

Rupaul again! | Zenni Optical

Stop it! Behave. It’s not that kind of flame and not that kind of drag.
 
The oleophobic AR coating is called that because in addition to resisting water the way the hydrophobic AR coating does, it also resists oil and grease (that’s the “oleo” part, as in “oleomargarine,” which is what margarine used to be called).

Magarine | Zenni Optical

The oleophobic AR coating has a slick surface on the lens that, like the hydrophobic AR coating, resists the buildup of water moisture on the lens and makes the lenses easier to clean than lenses with the standard AR coating.
 
But it also protects against smudging from fingerprints as well as facial oils. This is useful when you don’t want to use your superpowers to clean your glasses, which would give away your secret identity.

A couple kissing | Zenni Optical

Zenni also offers special mirror-finish oleophobic AR coatings for sunglasses. These come in gold, silver, and blue, and each is $19.95. The back of the lens has the AR coating, and the front of the lens has the reflective mirror-finish coating. The gold mirror finish looks great with frames that are gold, red, brown, or tortoiseshell, such as frame A10102114.

Gold mirror finish sunglasses | Zenni Optical

The silver mirror finish looks great with any frame color or style, especially A10102412.

Silver mirror finish sunglasses | Zenni Optical

The blue mirror finish looks great with silver, black, gray, blue, or gold frames, such as 521814, and is especially good at reflecting harmful blue light.

Man wearing sunglasses with blue mirror finish | Zenni Optical

Or check out this beauty in the blue mirror finish. The frame (A10161222) looks great, too.

Woman wearing sunglasses with blue mirror finish | Zenni Optical

Speaking of reflecting harmful blue light, soon we’ll be launching our newest AR coating, which is specially designed to block blue light. Keep checking the Zenni Blog – and website – for details!
 

Friday, March, 14 2014 by

Which Prescriptions Go With Which Lenses?

You’re ordering glasses online.


You enter your prescription and your pupillary distance. (The pupillary distance, abbreviated PD, is the distance from the center of one pupil to the center of the other pupil. It’s as necessary as your prescription to get glasses online.)

The website reads these items then recommends a lens for your eyeglasses.

 


How does it know which lens is right for you?


Here’s how. Each optical lens we offer, from standard index to high index, from single vision to multifocal, accommodates a particular prescription range. The website is configured to choose the thinnest lens for your eyeglasses.


Let’s take a look at the lenses we offer, the various prescription types, and the prescriptions within those types the lenses cover.

Zenni Prescription Rx

The two broad prescription categories are single vision and multifocal. Multifocal prescriptions comprise bifocals and progressives.
 
Nearsightedness and farsightedness are corrected according to the numbers in the Sphere (SPH) section of a prescription. For single-vision prescriptions, we can cover prescriptions for nearsightedness that go up to -20.00, for farsightedness up to +12.00.
 
If you have an astigmatism, this will be indicated on your prescription by numbers in the Cylinder (CYL) and Axis (sometimes abbreviated “X”) fields. For single-vision prescriptions, meaning those with no numbers in the Near-Vision Reading ADDition section (NV-ADD or just ADD), we can fill prescriptions in the CYL section up to + or – 6.00. The numbers in the Axis or X section just refer to the angle at which the CYL, an actual cylinder that’s invisible to the wearer, is placed on the lens.
 
A tiny portion of eyeglasses wearers have prism corrections on their prescription. We can fill these for single-vision (not multifocal) prescriptions up to 5.00 in any base direction (base up, base down, base in, or base out).

Eyeglasses Rx

For people who have numbers in the NV-ADD section of their prescription and want to get the type of multifocal glasses known as bifocals, which are eyeglasses with a lined reading-addition segment at the bottom of the lens, we can fill prescriptions for nearsightedness up to -9.00 and for farsightedness up to +6.00. We can go up to +3.50 on the NV-ADD.

Bifocals

The type of multifocal eyeglasses known as progressives are glasses with no visible line between the three different focal segments, which are distance (driving and watching TV) vision at the top of the lens, intermediate (computer) vision at the middle of the lens, and near (reading) vision at the bottom of the lens.
 
We can fill prescriptions with higher corrections for progressives than we can for bifocals. Our progressives go up to -10.00 for nearsightedness and up to +8.00 for farsightedness. Just like with bifocals or single-vision glasses, the CYL correction goes up to + or – 6.00. And just like with bifocals, the NV-ADD goes up to +3.50.
 
Here are our specific single-vision lenses, with the prescriptions they accommodate.

65mm Lens

For the mildest of single-vision prescriptions, those ranging from -2.00 to +1.00 or lower on the SPH and +/- 2.00 or lower on the CYL, the recommended lens is the 1.50 standard-index lens, which is free at Zenni Optical.
 
This lens is made of CR-39 plastic. CR-39 plastic is a polymer (a polymer is a large molecule composed of many repeated subunits, known as monomers) that gets its name because it was the 39th formula of a plastic developed by the Columbia Resins (hence “CR”) project in 1940. The first use of this plastic was to help create glass-reinforced plastic fuel tanks for the B-17 bomber in World War II.

 


CR-39 plastic has an index of refraction of 1.498, rounded up to 1.50 in the optical world.
 

Also free with single-vision prescriptions is the 1.57 mid-index lens. This lens is often described as “polycarbonate composite,” because in addition to polycarbonate the lens is composed of other polymers and resins that keep the lens thinner than the 1.50 lens. Its range is -4.00 /+2.00 or lower on the SPH and +/- 6.00 or lower on the CYL.

 
These are the two free lenses that come with single-vision glasses at Zenni if your prescription qualifies you for these lenses.
 

Yes-Its-Free
The 1.53 mid-index Trivex lens is a polymer lens that is the most impact-resistant lens available. It covers the same range as the 1.57 mid-index lens: -4.00/+2.00 or lower on the SPH and +/- 6.00 or lower on the CYL. It’s recommended for rimless, children’s, and sports eyeglasses because of its unequaled impact resistance. However, unlike the 1.50 and 1.57 lenses that are free with single-vision glasses, it’s $29.95. Also unlike the 1.50 and 1.57 lenses, it cannot be tinted.

 

Lens
If $29.95 is more than you would want to spend on an impact-resistant single-vision lens, the 1.59 pure polycarbonate lens, for $9.00, may be preferable. It covers the same prescription range as the 1.57 polycarbonate composite and 1.53 Trivex lenses, -4.00/+2.00 or lower on the SPH and +/- 6.00 or lower on the CYL. Also, it’s the second most impact-resistant lens available, just down a notch on impact resistance from the 1.53 Trivex lens, making it a good, less-expensive alternative for rimless, children’s, and sports eyeglasses.

 

polycarbonate-lens
However, like the 1.53 Trivex lens, it cannot be tinted, although it is available in glare-reducing polarized sunglasses and photochromic “auto-tinting” lenses, which turn dark in the bright sunlight and become clear again when you are out of the sun.

 

Occasionally, some people who have ordered rimless or half-rim glasses with 1.59 pure polycarbonate lenses have reported some chromatic aberration, meaning rainbow-like reflections, around the outer edge of the lens.

 

chromatic aberration
In addition, the 1.59 pure polycarbonate lens tends to scratch more easily than the 1.50, 1.57, and 1.53 lenses, because it’s a softer lens material.

 

The 1.61 high-index polymer single-vision lens provides a thinner lens for stronger prescriptions than mid- and standard-index optical lenses do. It is suitable for SPHs of -6.00/+3.00 or lower and, like all the others except for the 1.50 standard-index lens, CYLs that go up to +/- 6.00.

 
A high-index lens reduces the edge thickness for nearsighted (-) prescriptions and the center thickness for farsighted (+) prescriptions. In addition, it has a flatter, aspheric lens surface, which improves the visual quality the wearer experiences while reducing distortion of their eyes when others are looking at you.

High-Index-Lenses

Next comes the 1.67 high-index polymer single-vision lens. It provides a thinner lens for stronger prescriptions than the 1.50 standard-index, 1.53 Trivex, 1.57 mid-index, 1.59 polycarbonate, and the 1.61 high-index lenses. It covers SPHs of -20.00/+10.00 or lower and CYLs of +/- 6.00 or lower.

eyeglass lenses

Just like the 1.61 high-index lens, the 1.67 lens reduces the edge thickness for nearsighted (-) prescriptions and the center thickness for farsighted (+) prescriptions. Just like the 1.61 high-index lens, its aspheric lens surface improves the visual quality the wearer experiences while reducing distortion of the wearer’s eyes as seen by others.

 

The highest index single-vision lens we offer is the 1.74 high-index polymer lens. It’s for nearsighted (-) single-vision prescriptions only. It provides a thinner lens for SPHs of -8.25 to -10.00 or lower and covers CYLs of +/- 4.00 or lower.

prescription lenses
Just like the 1.53 mid-index Trivex and 1.59 polycarbonate lenses, the 1.74 lens cannot be tinted. It’s unavailable as a polarized or photochromic lens. Like the 1.61 and 1.67 high-index lenses, it has an aspheric surface, improving the wearer’s visual quality while reducing distortion of the wearer’s eyes as seen by others.

Bug Eye Specs

 

Anti-reflection coatings are good for any optical lenses, but they are especially recommended if you’re getting high-index lenses. They reduce glare and reflection and allow more light to pass through the lens, improving contrast, which improves visual acuity.

 
That covers our single-vision lenses.
 

For bifocals, we offer two lenses. Both come with the flattop 28 D-style near-vision reading segment lens. What that means is that the top of the bifocal segment lens is flat and the bottom is curved, making the bifocal lens appear like the capital letter D laid on its side. It’s called “flattop 28” because the widest part of the bifocal segment lens is 28 millimeters (mm) across.

normal bifocal lens
One of the bifocal lenses we offer is the 1.50 standard-index bifocal lens in CR-39 plastic. It’s just like the 1.50 standard-index single-vision lens, except it has the bifocal segment. This lens is good for SPHs of -3.00/+1.50 or lower with CYLs of +/- 6.00 and an ADD of +3.50 or lower.
 
The bifocal segment line is located 2 mm below the center of the lens. So if you get a lens that is 30 mm high, the minimum lens height for a multifocal lens purchased at Zenni, the bifocal segment will be at 13 mm up from the bottom, 2 mm below the 15 mm center line.
 
We also carry a 1.61 high-index aspheric bifocal polymer lens that provides a thinner lens for prescriptions with SPHs of -9.00/+6.00 or below with CYLs of +/- 6.00 or lower and an ADD of +3.50 or lower.
 
As with single-vision high-index lenses, an anti-reflection coating is recommended for high-index bifocal lenses.
 
Now let’s look at our progressive lenses.
 

Our progressive (no-line multifocal) glasses follow the same pattern as the single-vision lenses in terms of the index of the distance portion of the lens. They deviate a bit from the bifocals regarding the near-vision reading segment. Our progressive lenses are the style called “free-form,” which has a reading corridor of approximately 14 mm, roughly half the width of the bifocal lens.

 

progressive-lens-design
The 1.50 standard-index progressive CR-39 plastic lens covers SPHs of -2.00/+1.00 or lower with CYLs of +/- 6.00 or lower, and an ADD power of +3.00 or lower. The 1.57 mid-index progressive polymer lens covers SPHs of -4.00/+2.00 or lower, CYLs of +/- 6.00 or lower, and an ADD power of +3.50 or lower.

 

The 1.53 mid-index Trivex progressive lens has, like the single-vision Trivex lens, the highest impact resistance of all the lenses we carry. Also like the single-vision Trivex lens, this lens cannot be tinted. It’s a little thinner than the standard-index 1.50 index lens. It covers SPHs of -4.00/+2.00 or lower, CYLs of +/-4.00 or lower, and an ADD power of +3.00 or lower. It’s recommended for rimless and sports eyeglasses, but unlike the single-vision Trivex lens, it’s not recommended for children, who are prescribed multifocal glasses only in rare instances.

 

The features of the next progressive lenses, the 1.59 mid-index pure polycarbonate progressive lens, and the high-index 1.61 and 1.67 lenses, follow the same pattern as the single-vision lenses. The 1.59 progressive lens, which, like the Trivex lens, cannot be tinted (although it can be ordered as polarized, glare-reducing sunglasses or with photochromic, “auto-tinting” lenses), covers SPHs of -4.00/+2.00 or lower, CYLs of +/- 4.00 or lower, and an ADD of +3.00 or lower.

 

The high-index 1.61 progressive polymer lens covers SPHs of -6.00/+3.00 or lower, CYLs of +/- 6.00 or lower, and an ADD of +3.00 or lower. The high-index 1.67 progressive polymer lens covers SPHs of -10.00/+8.00 or lower, CYLs of +/- 6.00 or lower, and an ADD of +3.00 or lower.
 
As with single-vision lenses, anti-reflection coatings are recommended with high-index lenses.
 
Now you know all the features of all the prescription lenses Zenni carries!

ladycomputer

Friday, February, 21 2014 by

How To Get The Thinnest Lenses For Your Prescription

Unless you’re going for a look that says, “Kick me, I’m a nerd,” you probably want a pair of glasses with the thinnest lenses possible.
 
Nerd Glasses

 

But if you have a strong prescription and you’re ordering your glasses online, figuring out how to get the thinnest lenses possible can be perplexing.

Thick Glasses Lenses
Not to worry!
 
We’re going to make it easy for you.
 
All you’ll need is your prescription and a handy online tool that will estimate how thin your lenses will be.
 
This handy online tool is the Lens Thickness Calculator. It can be found here, at the OptiCampus website.
 
Before we talk about how to use the Lens Thickness Calculator, let’s look at the factors that can thin your lenses:
 
1)    Your prescription. This you cannot change to get a thinner lens. Doing so would be counterproductive, in that you would not be able to see well if you take it upon yourself to lower your prescription below what your eye doctor has prescribed.
 
silver frame eyeglasses
As a general rule, single vision prescriptions result in thinner lenses than multifocal prescriptions, all things being roughly equal. Multifocal prescriptions are those with an NV-ADD (Near Vision reading ADDition). Having an NV-ADD, or just an ADD, as it’s usually written, enables you to get bifocals and progressive glasses.
 
In addition, prescriptions with astigmatism corrections – if you have this, there will be numbers in the Cylinder (CYL) and Axis (sometimes abbreviated X) fields – generally result in thicker lenses than those without astigmatism corrections.
 
2)    Your lens index. The lens “index” is short for the lens’s “index of refraction.” That means how much the lens bends the light that enters it. That’s what refraction is. Bending the light focuses it right into the middle of your visual sweet spot, the retina, so you can see well.

Contact Lenses Diagram

You can change the index to thin the lens, up to a point. After that point, the law of diminishing returns kicks in. The lens that is recommended for your prescription will be the thinnest lens. Choosing a lens index that’s higher than the recommended lens index won’t make the lens thinner, and you’ll end up paying more for no improved result.
 
If this is confusing, don’t worry. We’ll clearly explain where the point of diminishing returns shows up when we look at the various lens indexes. In addition, you’ll be able to see it too, when you start playing with the Lens Index Calculator.
 
3)    Your lens width. This can have a considerable effect on your lens thinness. Once you have settled on the correct lens index, having determined that going to a higher lens index number won’t result in a thinner lens, the lens width – also known, weirdly, as the “eye size” – will be the last, and in some situations, the most important – factor in thinning your lens.
 
OK, are you confused enough yet?

Black Frame Eye Glasses

Yes? Let’s fix that right now.
 
We’re going to look at a prescription to see how different index numbers can make the lenses thinner. We’ll change the lens width – remember, that’s also known as the “eye size” (even though it doesn’t refer to the size of your eye) – to see how this affects the thinness of the lens.
 
To do this, we’re going to use a fairly common prescription. Most eyeglasses wearers are nearsighted, which means that the number in the Sphere (SPH) section on the prescription will be minus.
 

 
Most people who have an SPH correction also have an astigmatism correction. So we’re going to create a common prescription, with an average Pupillary Distance (meaning the distance between your pupils measured in millimeters, PD for short), 63; an average lens width (all together now: also known as “eye size”), 50 mm; and an average bridge (that’s the part of the frame that goes over your nose), 18 mm.
 
Here it is:
 
SPH -2.00, CYL -1.00, AXIS 90, PD 63, Lens Width 50, Bridge 18.
 
(For the sake of simplicity, we’ll assume that the prescription is the same for both eyes.)
 
Let’s put these numbers into the Lens Thickness Calculator and see what we come up with when we use different lens indexes.
 
With nearsighted prescriptions, the lens is concave. With farsighted prescriptions, the lens is convex. A concave lens is thinner at the center, thicker at the outer edge. A convex lens is the opposite.
 

Vision Prescription

 
You will see then, that with nearsighted prescriptions, the Center Thickness of the lens will be a lower number than the Edge Thickness.
 
Here’s what our formula yields with the 1.50 standard-index lens, which comes free on an order of single-vision glasses:
 
Center Thickness (CT): 2.0 mm / Edge Thickness (ET): 4.4 mm
 
Nice and thin at the center, but maybe not as thin as it could be at the outer edge. Let’s try it with the 1.57 mid-index lens and see what we get:
 
CT: 1.5 mm / ET: 3.6 mm
 
That makes the lens thinner at both the center and edge, and the lens is still free. Now let’s try it with the 1.59 pure polycarbonate single-vision lens, which costs $9.00, and see what happens:
 
CT: 1.5 mm / ET: 3.5 mm
 
You’re spending $9.00 for this lens, which is not a huge amount, but this slightly higher index doesn’t make the eyeglasses lens perceptibly thinner than the free 1.57 lens does. Now we’re starting to see the law of diminishing returns come into play.
 
Brown Frame Eyeglasses
However, even if the lens would be just as thin with the 1.57 lens, it would be worth it to spend the $9.00 on the 1.59 pure polycarbonate lens if you’re getting rimless glasses or if you’re buying glasses for kids who can be expected to treat the glasses roughly.
 
That’s because the 1.59 lens is a more impact-resistant lens than the 1.57, which is still a fine lens for people who treat their glasses with care.
 
Now we’re really going to see the law of diminishing returns at work when we go up a notch, to the 1.61 high-index single-vision lens. Here are the results of this lens:
 
CT: 1.5 mm / ET: 3.5 mm
 
No change, and you’re now (theoretically) spending $19.95 on a lens that isn’t any thinner than the 1.59 pure polycarbonate lens that’s $9.00, and is only a tiny bit thinner than the 1.57 mid-index lens that’s free.
 
But even after you’ve selected the lens index that will give you the thinnest lens, you can still thin the lens further, if you narrow its width.
 
Let’s lower the lens width to 48 mm and see what happens with each lens. First, the 1.50 lens:
 
CT: 2.0 mm / ET: 4.1 mm
 
The Edge Thickness is a tiny bit better, 4.1 mm as opposed to 4.4 mm on the 50 mm-wide lens. How about the 1.57 lens?
 
CT: 1.5 mm / ET: 3.3 mm
 
Now we’re talking! We’ve shaved half a millimeter from the center and almost a whole millimeter on the edge, just by lowering the lens width.
 
How about with the 1.59 lens?
 
CT: 1.5 mm / ET: 3.2 mm
 
No change on the center, only one tenth of a millimeter on the edge. Stand and salute the diminishing returns on parade!
 
Let’s take a quick look at the 1.61 lens, just to make sure it doesn’t make the theoretical eyeglass lenses any thinner:
 
CT: 1.5 mm / ET: 3.2 mm
 
That would cost $10.95 more for no improved result.
 
So unless you want a pure polycarbonate lens for its impact-resistance feature, you’re wasting your money by spending $9.00 to get a higher-index 1.59 lens that won’t be any thinner than the free, 1.57 mid-index lens.
 
But once you’ve confirmed which lens index that will result in the thinnest lens for your prescription, and you want to thin the lens even further, play around with the lens width on the Lens Thickness Calculator. Go as low as you can and still keep the lenses wide enough for a comfortable field of vision and attractive look.
 
For example, the 48 mm wide lens may be just as narrow as you can go without making the glasses look too small. But if you can narrow the lens even more, you will see that the lens will continue to become thinner.
 
If you do check out the Lens Thickness Calculator to see the estimates of different thicknesses that different lens indexes and lens widths yield, keep a few things in mind: When you are selecting the Lens Material Type, the categories listed on the Lens Thickness Calculator don’t exactly correspond to the lens index categories on our website, although they are basically the same.
 
For example, the Hard Resin lens is the 1.50 lens. The 1.56 mid-index is essentially the same as the 1.57 mid-index. The polycarbonate lens is the 1.59 mid-index lens. All of the 1.60 lenses on the Lens Material Type list are the equivalent of the 1.61 high-index lens.
 
So to recap, stick with the lens that our website recommends when you enter your prescription. That will get you the thinnest lens for your prescription, if you also select the lowest lens width that will also work well for your face size and shape.
 
Good luck!

 

Mens Eyeglasses

 

Thursday, February, 13 2014 by

Are Wood Eyewear Frames Right For You?

wood frames
 
Wood, as an eyewear frame material, can work on anyone as there are so many different colors and styles available. You don’t have to go for the super exotic pattern of zebra wood or create high drama in burgundy-stained, polished wooden eyeglass frames unless that’s your personal style. Both of these looks can be stunning if that’s who you are.
 
But, if the way you roll is more rustic or understated, then wooden eyewear frames are still going to be a good choice because you can also find subtler grain patterns and toned down, natural wood colors. Either way, the main advantage of wood eyewear frames, other than being super sturdy and eco-friendly, is to let your true personality stand out.
 

Be a Celebrity

 
Celebs such as Will Smith and Catherine Zeta Jones enhance their personal style with wooden frames and you can do the same. You may want to think of it as being your own dresser. No, you won’t be getting paid to make some movie star look fabulous, but it’s something great to do for yourself to be a star in your own life. Who knows, you may even end up getting paid back in compliments for the extra time you took to choose those flattering, new prescription glasses or sunglasses with wood frames for yourself. Your goal should be to choose wooden eyewear frames that you really love and that make you look your absolute best.
 
Before you settle on a specific wood eyewear frame, take the time to look at the different colors and textures available first. Chance are, if you really love a wood’s color and look, you’re going to be able to carry it off wonderfully. Don’t get distracted so much by the names of the different woods such as whether the eyewear you want will be zebra wood, birch, bamboo, ebony, pear or another variety, but instead keep an open mind as you browse wooden eyeglass frames and let your heart guide you as you react to each frame you see. If you fall in love with several different frames at once, just narrow things down later by picking the one that suits you best. You and your new wood eyewear frames are then destined to live happily ever after. Cue the cooing doves.
 

The Whole Enchilada

 
The overall style of your glasses is also going to make a difference in how the wood frames look on you such as whether you opt for a modern, vintage or classic style. Most of us are going to look good in more than one main style, so you may want to spice up your eyewear wardrobe and go for something different than the same basic lens shape and frame combination you usually choose. Keep it real and bring out your own personality though, or it’s just not going to work. We are not all Cee Lo Green or Tom Cruise, yet all still have the potential of looking amazing in glasses.
 
Another part of the whole to keep in mind when putting together a wood-framed eyewear look is the color of the lenses. This is going to be mainly a factor when picking sunglasses with wood frames, but you may want to consider tinted lenses for daily wear as well. If you’re still having trouble deciding on a wood frame and lens combination, try describing the overall look of the eyeglasses to yourself in one word such as “sporty,” “trendy” or “creative.” If the words “not me” come up in your brainstorming, then move on to another combination. The right wood eyewear frames are going to be out there for you.
 

Thursday, October, 31 2013 by