Prescription glasses: about lenses

Prescription glasses

Lens type

Lens Materials

New Lenses

 

Reading your prescription

Cleaning

Common Questions

 

Choose prescription glasses lenses for your lifestyle

Your lifestyle and your preferences are the best guides for you to find the perfect lenses for your needs. You can make your own decisions about the various lens choices that are available to you when your buy prescription glasses. To read more about lens options, follow this link to eye glasses lenses.

You can start by considering your lifestyle, and thinking about when and how you use your eyes. Then, learn more about prescription lens features, options, and services. After that, you will be able to select from the menu of prescription lens options the characteristics that will most support your lifestyle. When you are ready, follow this link to our lens wizard which will guide you through the process.

PRESCRIPTION EYEWEAR LENS TYPES

Single vision lenses

Your eyes may need vision correction only for distance, only for reading, or for both. If you need correction only for distance vision, then you only need single vision lenses. With single vision lenses, you can look through all areas of the lens and see clearly.

If you need vision correction only for reading and you do not have astigmatism, then you can buy non-prescription reading glasses. If you do have astigmatism, you need prescription reading glasses. In either case, these are still considered single vision lenses.

Multifocal lenses

If you need vision correction for both distance and reading, then you can use two pairs of glasses, and alternate depending on what you need to see. Or, you can choose multifocal lenses (bifocal lenses, trifocal lenses, or progressive lenses). Many people find it inconvenient to switch to another pair in order to read something.

Multifocal lenses divide the lens so that part of the lens is for reading and part of the lens is for distance vision. Bifocal (two areas) and trifocal (three areas) lenses have visible lines that separate the different areas of the lens.

Progressive lenses

Advantages

Progressive lenses, which are sometimes called no-line bifocals, are actually trifocal lenses without the visible lines. Progressive lenses were developed because many people wanted the convenience of not having to change their prescription glasses to read, but they did not like other people to see the visible line. Progressive lenses do have another benefit however, which is that you feel a smooth transition when you move your eyes from distance objects to close up objects. With a lined bifocal, the transition between viewing areas can be somewhat uncomfortable.

Disadvantages

So progressive lenses offer the convenience of multifocals without the visible line. However, progressive lenses are much harder to use and to adapt to than bifocal or trifocal prescription glasses, and they are much more expensive.

In order to create a no-line progressive lens, there are two large areas of the lens that you cannot see through. Imagine what an hourglass looks like. This is the shape of the area of the progressive lens that you can see through. Objects seen through the areas of the lens to the left and right of the narrow middle section will be distorted and you cannot see anything there.

The bulge areas at the bottom and top of the lens are for near and distance vision, and the thinner corridor connecting them is for intermediate distances. On either side of the narrow portion of the hourglass objects will appear distorted. In general, more expensive progressive lenses like Varilux have a wider corridor, and less expensive lenses have a narrower corridor that can restrict the viewing area considerably.

On smaller lens sizes, it is necessary to slice off a portion of the bottom (reading section) of the lens in order to install the lens in the frame. As a result, the smaller the frame size, the smaller will be the reading portion of the lens. Follow this link to learn more about the features of eyeglass frames, and some of the restrictions regarding progressive lenses.

In order to use a progressive prescription glasses, you must learn to move your head to see things; you cannot just move your eyes because you will be looking through a blurry part of the lens. This is called adapting to the lens. Most people can adapt within a month, but some people never adapt. It is common to experience dizziness and headaches during the time that you are adapting. Getting accustomed to progressive prescription glasses can be difficult, and you must have proper instruction by an eyecare professional.

Sometimes, people who try progressive prescription glasses for the first time have a difficult time learning to look through the appropriate portion of the lens at the right time. Often a simple fitting adjustment to your prescription eyewear by your local optical professional can make all the difference. For more information, follow this link to read about progressive lenses.

Prescription reading glasses

If you need vision correction only for reading and you do not have astigmatism, then you can buy non-prescription reading glasses. If you do have astigmatism, you need prescription reading glasses. In either case, these are still considered single vision lenses.

Non-prescription reading glasses simply magnify objects that are close to us, like the letters in a book. Your eye doctor can determine the magnification power that is best for you, or you can figure it out by yourself through trial and error. A doctors prescription is not required in order to select a reading lens. Drugstore reading glasses are simply eyeglasses frames with magnifying lenses pre-loaded in a range of powers with stock lens powers. It is usually less expensive to purchase reading eyeglasses this way, but stock lens powers rarely provide a optimal vision correction. For best results, reading lenses with magnification customized to your needs can be installed in any pair of eyeglasses frames.

PRESCRIPTION EYEWEAR LENS TYPES

Once you have determined the best lens type for your lifestyle, preferences, and budget, you can then choose the lens material. There are three basic types of lens material for prescription eye glasses--hard resin plastic, polycarbonate plastic, and high index plastic.

The rule of thumb

If your prescription is lower than +/-4.00, then hard resin is the best choice for you. If it is above +/-4.00, then high index plastic is best for you. If you are a child or an active adult and need some eye protection, then polycarbonate is best for you.

Lens Material Sphere Range
0 to +/- 3.00
Sphere Range
+/- 2.00
to +/- 5.00
Sphere Range
+/- 4.00
to +/- 8.00
Sphere Range
+/ - 4.00
to +/- 8.00
Hard resin recommended      
Mid-high index 1.56   recommended    
High index 1.60     recommended  
Ultra high index 1.67       recommended
Polycarbonate recommended      
Polycarbonate aspheric   recommended recommended  

Hard resin lenses are good for most people. Polycarbonate lenses are virtually shatterproof, and are highly recommended for children and active adults. By active we refer to any activity that includes a possibility of receiving a blow to the face. For example, policmen, firemen, tennis and ball players, aggressive sporting activitiesjust to name a few. Wearing polycarbonate lenses may not save your eye, but they will certainly help, and a little added protection cant hurt!

In general, if the sphere on your prescription is at +/-2.00 or lower, you will not benefit from the more expensive thin high index lens types. Hard resin or polycarbonate lenses will be just fine for you. If the sphere on your prescription is higher than +/-2.00, you will benefit from the selection of a thin lens type. Thinner lenses have three advantages: they do not look thick, they do not magnify or minify your eyes when seen by others, and they are lighter.

In general, the thinner and lighter the lens, the more expensive it will be. High index is the most common thin lens material, and aspheric is the most common thin lens design. Polycarbonate lenses can be purchased as aspheric, giving you the advantage of polycarbonates strength together with aspherics thinness. The thinness of high index lenses is characterized by the index of refraction (IR). Mid-high index lenses are commonly around a 1.56, high index lenses are around 1.60, and ultra-high index lenses are 1.66 and above. All rimless eyeglasses must use polycarbonate, Trivex, or high index lenses to avoid cracking.

After you have selected the best prescription glasses lens material for your personal situation, you can choose among other lens features and options, like sun-sensitive, scratch coating, anti-reflective coating, and UV protection (UV protection is always inherent in high index and polycarbonate lenses). If you want sunglasses, additional options could include tint, polarization, and mirror coatings. Additional lens services would include a mounting fee (applies only for rimless frames), and rolling and polishing (applies only to higher power lenses being mounted in certain frame types). For more information on the various lens options, follow this link to eye glasses lenses.

How thin are the thin lenses? How thick are the thick ones?

The plastic used for lenses in prescription eyewear must have at least a 2.0 mm center thickness according to US law. The thickness at the lens edge depends on the strength of your prescription, your pupillary distance, the eye size of the frame, and the lens material. Because of all of these factors, it is nearly impossible to select a lens by its thinness. In general, the thinner and lighter the lens, the more expensive it will be. To make the optimal thickness/price choice for your personal situation, use the chart above as a guideline. You can choose to spend less money and have a thicker lens, or more money to have a thinner lens. Also, within the mid-high index, high index, and ultra-high index categories you can also choose an aspheric design for additional thinness.

NEW LENSES

Adjusting to lenses

You will need to learn how to adjust yourself to your new glasses, whether you get your new glasses from eyeglasses.com or any other optical store. The adjustment period could be very quick, or it could take a month, depending on you, your glasses, and your prescription. There are some ways to make the process easier, and to solve problems more quickly.

If your prescription is lower than +/-4.00, then hard resin is the best choice for you. If it is above +/-4.00, then high index plastic is best for you. If you are a child or an active adult and need some eye protection, then polycarbonate is best for you.

Common adjustment problems and solutions

It is very common to experience a feeling of disorientation while you adjust to your new glasses. If you are having trouble adjusting to your new glasses, work through this list in order:

  1. If your prescription has changed recently, your eyes need extra time to adjust to the new lens.

  2. If you are wearing multifocal lenses (progressive, bifocal, and trifocal lenses), you must learn to move your head, not your eyes.

  3. The center of the lenses must be positioned directly in front of your eyes. Make an adjustment to the positioning of the glasses on your face, and be sure the glasses stay in that correct spot.

  4. ) If you tried #1 through #3 and you still cannot adjust to your new glasses, it is possible that the pupillary distance measurement was taken incorrectly. It is also possible that your eye doctor gave you the wrong prescription (sometimes they do make mistakes!)

  5. If you tried #1 through #4 and still are not satisfied with your lenses, send the glasses back to us (if you bought them from us). We will double check to be sure that we made the lenses exactly to your specifications. We will then give you a full refund.

READ YOUR PRESCRIPTION

We strongly recommend that you fax your prescription to us. We can read your prescription and then help find the best prescription eye glasses lens for you. For multifocal orders, we require that you fax your prescription to us.

Your prescription

Prescriptions have a certain format that is typically followed. The first line of your prescription is always for the right eye, sometimes designated the OD. The second line is for the left eye, sometimes designated OS. The prescription for each eye is divided into Sphere, Cylinder, and Axis values. It is common to have no values for any one of these, in which case you might see the letters PL or plano, or to have values for all of these. Sometimes the prescription may say OU which means both eyes.

Multifocal prescription

If your prescription is for bifocals or trifocals of progressive lenses, there may be additional information on the prescription that says for example Add +2.50. This is important information if you are ordering reading or multifocal lenses. The numbers are expressed in diopters (a universal value system) that tells the power of the lens.

On a prescription for multifocal glasses lenses, you will see information designated as add power. Your add power is simply the magnification that is added to your sphere value for distance vision, in order to create a field of view for reading. For example, if your sphere value for distance viewing is 3.00, and your add power is +2.00, then your near vision correction is 1.00. Or, if your sphere value for distance viewing is +1.00 and your add power is +2.00, then your near vision correction is +3.00.

Pupillary distance PD

An accurate PD is a required measurement in order to make prescription glasses, and you cannot purchase from eyeglasses.com without one.

Your PD is the distance in millimeters between your pupils (the centers of your eyes). Your adult PD never changes, and it averages 60 millimeters (mm) for women, and 64 mm for men. Sometimes your eye doctor will write your PD for each eye (for example 33/34, called a monocular pd). Or, the eye doctor may write the PD as 67/64. This means that your PD for distance vision (or DPD) is 67, and for near vision (or NPD, for reading eyeglasses or multifocal lenses) it is 64. Your near vision PD is almost always 3mm less than your distance vision PD.

CLEANING

Cleaning prescription lenses

The best cleaning method for eyeglass lenses and sunglasses, including lenses with anti-reflective coating always begins by moistening the lens. Lenses should never be cleaned dry, never with a piece of clothing or a paper towel or toilet paper or Kleenex containing moisturizer. To clean your lenses, start by putting your glasses under lukewarm running water. Get your finger tips soapy, and gently rub the lens. Rinse soap off the lenses, and then pat dry with a microfiber lens cleaning cloth. Never rub the lenses with any cloth, just dab them until the water droplets are gone.

Cleaning prescription glasses frames

Cleaning your glasses is also best done with soapy warm water. You can also take your prescription glasses to a local optical stores, which has a machine for cleaning eyeglass frames. However, if your frame has any inlaid gems, you should not have them cleaned by machine, only by hand.

COMMON QUESTIONS

Can I hurt my eyes with the wrong lenses?

There is no clinical evidence to suggest that looking through lenses with the wrong prescription or pupillary distance configuration can cause damage to your eyes. However, there could be other undesirable consequences (especially for people with stronger corrections), such as headache, dizziness, and vertigo. Some of these effects could cause a dangerous situation if you are driving, handling machinery, or otherwise reliant on your eyeglasses for your safety or the safety of others.

Can my new prescription eye glasses make me dizzy or give me headaches?

No. Prescription eyewear lenses cannot be separated from lens installation. Lenses must be purchased and installed by the same company. However, it is possible to buy prescription frames from one store and have the prescription glasses lenses installed at a different store.

You may experience some of these effects with a new pair of prescription eyeglasses, or a new prescription. The effects could fade over time, but we strongly suggest that you visit your local optical professional in order to determine the best course of action.

Can I buy prescription lenses from one store, and have them installed elsewhere?

No. Prescription eyewear lenses cannot be separated from lens installation. Lenses must be purchased and installed by the same company. However, it is possible to buy prescription frames from one store and have the prescription glasses lenses installed at a different store.

My frames are broken, but my lenses are still good? Can I reuse them?

Prescription glasses lenses can often be re-cut to fit new prescription frames, but there are some restrictions. The new prescription frame must either be the exact same frame model and size as the broken frame, or it must be smaller in every dimension (height and width). Your local optical retailer should be able to examine your prescription lenses and help you select a new prescription frame for them.

Does it matter which lens brand I choose?

Your choice of prescription lens brand is a personal decision, which is generally a tradeoff between price and quality. In general, better quality brand merchandise is more expensive. In prescription lenses, a more expensive lens usually means a better quality lens, or a lens with a wider viewing area (in the case of progressive lenses). In some cases however, it may be difficult or impossible for a consumer to notice the difference between a high quality prescription lens and a low quality lens. Anti-reflective and scratch-resistance coatings typically adhere better to the lens if they are applied by the lens manufacturer than if it is applied by a lens laboratory.

Prescription Safety Glasses

We do not sell safety glasses at eyeglasses.com. There are many different types of safety lenses and eyeglass frames depending on your job or your activity. Safety glasses should only be dispensed in consultation with your eye doctor and local optical professionals.

Childrens Glasses

We offer a selection of prescription glasses for children. The best way to begin fitting your child for prescription glasses is to get the childs PD measurement. When you have that, you should call our customer service department and discuss the needs of your child, and we can either find the perfect prescription glasses for your child or refer you elsewhere.

Prescription sunglasses

You can build prescription sunglasses the same way as prescription glasses. Begin by selecting a pair of eyeglass frames or sunglass frames that can hold a prescription. Lower quality sunglass frames are not designed to hold a prescription lens, and are called non-RXable. RXable sunglasses are sunglass frames that can accept a prescription lens. Follow this link to read more about prescription sunglasses.