Eye Care Blog

What Are Zeiss Progressive Eyeglass Lenses All About?

Added 13/4/2010

In the pase, it is often happened that our parents would make choices for us, if we want eo buy a pair of glasses. They don’t trust we can make choices by ourselves. But now thanks to the development of technology, we have more chioces to opt and parents give the rights to ourselves.And if I will buy glasses, I would choosezeiss progressive eyeglass lenses.

Conversations with your eye care doctor will assure you receive the specific type of progressive lenses needed. So be sure to ask some of the questions mentioned here to ensure you get the correct information for your particular situation.

There are some distinct advantages to choosing progressive lenses.

They are often known as no-line bifocals as the visible line is now no longer visible and help to disguise the fact that you're now that certain age where reading glasses are now necessary. You can simply appear to be the fashionable and trendy person you've always been.

They allow comfortable viewing at your computer keyboard and monitor enabling you to work as efficient as you need to.

Measurements are taken of each eye to ensure that the correct vision corridor is prescribed for your progressive lenses. You will not experience image jumping that is so common in trifocal or bifocal glasses. The reason for this is that the lens power is designed to be seamless allowing you to change focus comfortably both near and distance viewing.

As with any new eye wear there may be a short adjustment period. That holds true for progressive lenses as well; which is usually a couple of days. In the beginning you may experience slight occasions of objects appearing slightly blurry but as your eyes adjust your vision will correct itself.

Lens manufacturers devise compact designs that allow for larger reading zones within the short corridor design which translates into smaller, more comfortable and more fashionable frame choices. Progressive lenses are the most popular lenses for correcting nearsightedness. They are designed mainly for computer use that offer a wider intermediate zone.

The adaptation to modern progressive lenses is made easy as the corridor of vision is vertically down each progressive lens.

Anyway, zeiss progressive eyeglass lenses are designed to provide lens power for all viewing distances both near and at a distance. No more peering over or under your lenses as your vision will remain clear in any direction you turn your head.

Firmoo.comis the fastest growing online community selling affordable yet high quality prescription eyeglasses, prescription sunglasses and other eyewear. Firmoo’s return and refund policy makes your purchase with Firmoo risk-free. Check out our $8, $20 and $10 eyeglasses frames to fit your budget and vision needs.

Category : bifocal progressive | Comments (0) | Write a comment |

Tips For Buying Varifocal Glasses Online

Added 13/4/2010

If you are someone who needs a new pair of glasses or who alreadywears prescription glasses then you may want to consider taking a lookat varifocal glasses when you make your next purchase. You will enjoy a lot of discounts online.

Over the last three years thousands of people have been turning tothe internet looking for online suppliers of prescription glasses. Theprices of prescription eye wear online is at an all time low andsavings of up to 75% of the normal retail price is not unheard of.

HOW TO CHOOSE A FRAME THAT SUITS

There are certain face shapes that suit certain lens shapes and manyguides to this are floating about the internet. The general guide islisted here:-

Triangular Faces

This shape is defined by a broad forehead and narrow mouth and chin.Frames with a thin rim and vertical lines will help balance the bottompart of the face. Frames should not sit too high on the face. Avoidlarge frames, heavy nose bridges, bold colours and square shapes.

Oval Faces

More frames look good with this face shape than any other, as long as the size of the frames is in proportion to the face.

Round Faces

To play down the roundness, select frames with straight or angularlines. Deep colours such as black or tortoise also minimizes fullness.

Oblong Faces

Long narrow faces are similar to square faces in that the chin andcheek are of nearly the same width. Facial length, however, is fargreater than the width. Frames should cover as much of the centre ofthe face as possible in order to minimize the length.

Square Faces

Compliment a square face with frames that are slightly curved. Thetop of the frames should sit high enough on the face to downplay thejaw line.

HOW TO CHOOSE A FRAME THAT FITS

You can use this as a guideline by comparing them to your own glasses

HOWEVER, this is NOT the BEST way to obtain a good fitting frame. Atspex4less there are two further measurements that are FAR easier tounderstand and ensure a much better result.

Frame sizes are usually in the format "50 - 20 - 140". In thisexample this means that the lens diameter is 50mm the bridge distanceis 20mm and the arm length is 140mm. This can usually be found on theinside arm or on the back of the bridge.

Each of the frames on the website includes the total frame width inmillimeters and total frame depth in millimeters, compare these to yourown frames for a good fitting frame.

COMMON ABBREVIATIONS

Plano, 0.00, Infinity - All mean the same thing nothing! Or No correction is needed.

DS - "Dioptre Spheres" Usually appears under the CYL box indicatingthat there is no astigmatism (No CYL value). However, this can sometimeappear after a reading addition.

OD - Means your right eye.

OS - Means your left eye.

PD - "Pupillary Distance" is the distance between the centre of onepupil to the centre of the other in millimeters. I would like to take amoment to talk about your "PD" as this has caused much debate indispensing glasses online.

Opticians generally will not give this to you as they will probablyfigure that you wish to buy your glasses online and not from them. Inmost cases, except for those with particularly high prescriptions, wecan calculate this usually within a millimeter using experience andcertain order criteria such as your gender and the size of frame youhave chosen etc.

HOWEVER, it is very simple to measure your own "PD". The best way isto have a friend help you. Look at a point in the distance whilst yourfriend takes the measurement in millimeters, if you wanted to be superaccurate measure the left side of the left pupil to the left side ofthe right pupil.

Outside UK prescription format = EG: +1.25 (-1.00) x 180° Althoughit looks different it's the same. The first value is the SPH, thesecond in brackets id the CYL, and the x180° is the Axis in this case180.

HOW TO CHOOSE THE BEST LENS

Lenses come in many flavours and again, at first, things can becomea little confusing. But don't worry. I am here to explain them all indetail so that you can understand and choose the best lens option foryou.

Firstly lenses can be made in two materials Organic (Plastic) or Mineral (Glass).

Most lenses sold today are of the plastic variety as they are farlighter than glass. In some rare occasions when extremely thin lensesare required for very high prescriptions glass can be the best option.

Each lens will also have what we call a "Refractive index" The wayin which the refractive index is calculated is not important at thistime. What is important is what it means to the thickness of the lens.

Most people think that when we say a 1.6 lens that this means it is going to be 1.6mm thick, THIS IS WRONG.

Basically the higher the number the thinner the lens will be. Thisis because materials that bend light more than others have a higher"Refractive index" and hence a shorter or longer focal length. Thismeans that the same correction and focal length can be achieved from"less" lens (material) making them thinner.

Here is a key to choosing the best lens.

Standard Plastic CR39 (1.5) We use 1.56 on all standard lenses Idealfor most prescriptions (prescriptions with powers stronger than +3.00and -3.00 will start to look thick, powers between the two will lookfine).

Plastic (1.6) An ideal option for prescriptions up to +5.00 and downto -5.00. 1.6 lenses are 23% thinner than standard plastic.Prescription outside this range will start to look thick.

Plastic (1.67) Probably the most popular of the thinner lensoptions. 15% thinner than the 1.6 and 25% flatter. Ideal forprescriptions up to +7.00 and down to -7.00 prescription outside thisrange will look thick.

Plastic (1.74) The thinnest plastic lens available on the market.50% thinner than the 1.5 standard plastic and 30% lighter than theglass equivalent. Great for mid to high prescriptions.

Glass (1.7) An ideal budget thin lens for "-" power prescriptions up to - 10.00. However, they will be heavier than plastic

Glass (1.8) Rarely used but good for high power prescriptions. Expensive option.

Glass (1.9) Rarely used but excellent for high power prescriptions. Expensive option.

YOUR PRESCRIPTION AND AVOIDING COMMON MISTAKES

"*Please pay particular attention here*"

Your prescription may seem a little confusing at first glance but it really is quite simple to understand.

Firstly, every prescription follows the same format wherever you arein the world. There may be a few variations and abbreviations, but Iwill explain them later.

Let's describe what it all means first.

Each prescription will have a left and right value for the correction of your vision within the following boxes:

"SPH" (sphere). The correction for long or short sightedness.

"CYL" (cylindrical). The correction for an Astigmatism.

"AXIS" The axis that the correction for the Astigmatism needs to be set at.

Sometimes an Add or Addition, always "+" value is included for us todecipher your reading prescription, but only if you require glasses forboth distance and for reading.

In some rarer cases Prism and Base is used for the correction of double vision.

On our website and most of the others out there you can select yourprescription from drop down boxes so that you can simply copy thedetails you have on your written prescription.

HOWEVER, as many people know there are always exceptions to any rule!

My advice is to use this guide if you have never worn glassesbefore. Many people who are already wearing glasses know which shapessuit them and which don't.

Choose a pair of glasses similar to the ones you have at the moment,OR, if you are trying to find a new look why not go for a rimless orsemi-rimless frame with the same lens shape as your current glasses, orvice versa.

*VERY IMPORTANT - Do not fall for the most common mistake!*

The single most common mistake when entering prescriptions online is selecting a " +"value instead of a "-" value or vice versa.

Your prescription may consist of both "+" AND "-" Values. For example:-

SPH (Spherical) will consist of a + or - power (unless 0.00) in 0.25 steps. EG, -0.25, -0.50, -0.75, -1.00, -1.25 and so on..

CYL (cylindrical) may consist of a + or - power in 0.25 steps. EG, -0.25, -0.50, -0.75, -1.00, -1.25 and so on..

Axis will consist of a numerical value from 0 to 180, BUT, only when you have a CYL value.

Note: Usually opticians will write the "-" and "+" signs above the value.

ADD / Addition Will only consist of a + value as is it is what itsays on the tin, an "addition". We add this value to your distanceprescription if you need reading glasses as well as distance or forbifocals.

Note: Some opticians will write out your complete near prescriptionunderneath your complete distance prescription. In this case you willneed to call us to tell you what the "add" is.

Lens Types

There are also many different styles of lenses. Lenses for singlevision correction e.g. distance or reading, to Bifocals and Varifocalsfor the correction of both distance and reading within one pair ofglasses.

Varifocals

Firstly I would like to talk about Varifocals as there is muchdebate about whether or not they should be supplied online. AtSpex4less we do not feel that it is morally correct to supply theseonline just yet, UNLESS it is part of our Re Glaze Service and you havevarifocal lens in your glasses already.

Varifocals blend gradually from your distance prescription throughyour intermediate prescription in to your reading prescription. Thismeans that the lens has to be set at exactly the correct height in theframe to start with.

The crucial measurement required to align varifocals is the heightin millimeters from the centre of your pupil to the bottom of the newframe, this measurement cannot be taken online.

Although it is becoming common practice online to use averages andexperience along with other factors such as order information tocalculate some measurements such as the "PD" we spoke about earlier, itis not yet possible to do this with Varifocals. Some online companieswill still provide varifocals for you and you may get lucky. HOWEVER Iwould not advise anyone to do this until technology allows us to takethe accurate measurements needed.

We are currently working on a varifocal system that should allow usto supply Varifocals accurately. I will let you know when the resultsare in.

Bifocals

Bifocals are basically distance glasses with a reading segment inthe bottom. Unlike Varifocals Bifocals are commonly sold online as theheight measurement is far less crucial and averages can be used withgreat success. Due to the fact that there is no gradual phase fromdistance into reading and they are just distance with a reading segmentBifocals have a far wider corridor for reading than Varifocals but haveno intermediate correction.

There are also various types or "shapes" of the reading segment.

Typically the standard is the "D Seg" this one looks like the letterD on its side with the flat part it the top hence the name D Seg.

There is also a "round" segment in various sizes and executive or "EType" bifocal where the whole bottom half of the lens is dedicated toreading (Great for people who do a lot of reading at work using plansetc).

Bifocals are only available in standard plastic, standard glass and 1.6 plastic.

Single Vision

"Single Vision" lenses can be used for just distance, justintermediate or just reading hence the name "single vision". However,many people who are short sighted "-" Power SPH prescriptions will beable to read with their distance glasses. Single vision lenses areavailable in both materials and all indexes.

Lens Coatings

Tints

Tints can be used to make "Plastic" lenses in to sunglass lenses andare available in many colours. However, 1.67 and 1.74 lenses cannot betinted as they already contain an antireflective coating to reduce"Power rings" which I will explain later.

Photochromic

Photochromcs are usually referred to as "Reactolite" which is abrand name for the glass variety or "Transitions" which is a brand namefor the plastic variety.

Basically they do the same thing. These are lenses which are clearindoors but then "react" to UV (Sunlight) and "transform" intosunglasses.

NOTE: As photocromic lenses require UV to change, using them behinda car windscreen will not work as effectively as normal due to thewindscreen filtering out some of the UV.

However, we have found that the glass reactolite works better thanthe plastic behind a car windscreen, but not as good as the plastic innormal conditions.

Polarized

Light reflected from surfaces like a flat road or smooth water isgenerally horizontally polarized. This horizontally polarized light isblocked by the vertically oriented polarizers in the lenses filteringour glare and allowing you to see below the water line. Available ingrey or brown polarized lenses are ideal for fisherman and also fordrivers.

Anti Reflective

Usually an anti reflective coating is referred to as an "MAR" (MultiAnti Reflective Coating). There are many benefits to an MAR. Firstlythey are far more aesthetically pleasing as they reduce the amount oflight reflecting off your lenses especially when having your photographtaken.

Other benefits include:-

o Reduced glare when driving at night

o People can see your eyes and not a patch of light

o Filters out radiation from computer screens

o Reduces "Power rings" visible rings on the lens in highprescriptions which is caused by light constantly bouncing back andforth within the lens due to total internal reflection.

o Provides UV protection

o Anti static aiding lens cleaning

Spex4less provides MAR coated glasses for characters in CoronationStreet to reduce reflections from studio lights and reflections ofcamera men in the characters glasses.

SUMMARY

The internet is reaching further and further in to our daily lives as more and more products become available online.

Buying your glasses online is surely going to be an exciting andhassle free experience now that you have taken time to read this guideand you could also save yourself a small fortune.

This guide to help you avoid any pitfalls and decide upon a frameand lens that will suit, fit and work, so saving you valuable time andmoney!

Firmoo.com is the fastest growing online community sellingaffordable yet high quality prescription eyeglasses, prescriptionsunglasses and other eyewear. Firmoo’s return and refund policy makesyour purchase with Firmoo risk-free. Our collection of 8 and 10 dollar frames are the perfect choice for budget-conscious patients.

 

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