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Lenses & Prescriptions

Lenses:

We know that the optical world entails a variety of different lenses available to you, which can be confusing. Not sure which lenses you are looking for? No need to worry, please refer to the descriptive list that follows:

Single Vision Distance Lenses – these lenses will aid you with seeing and sharpening objects and print that are far away

Single Vision Reading Lenses – these lenses will aid you with seeing and magnifying text, or, in other words for just reading books, magazines, the newspaper, etc. Remember, you are not able to see things in the distance with this type of lens.

Progressive Lenses – these lenses will be worn at all times to accomplish your daily activities. They are a blended lens mixing both your distance and reading prescriptions together. Most people who wear these lenses have an ADD on their prescription from their optometrist or ophthalmologist. The Progressive lens gradient starts with your distance prescription, at the top of the lens and reaches your maximum addition power, or the full reading addition, at the bottom of the lens; creating an hourglass shape. It is also referred to as an “Invisible Bifocal Lens” and you should keep in mind that there will be minor distortion on each side of the lenses due to the blending of the different prescriptions; however a High Definition lens will reduce distortion. A rule of thumb is to point with your nose in the direction you want to see clearly and slightly move your head up and down to experience the different viewing distances in these lenses.

High-Definition Lenses – This type of lens will reduce the distortion found in a progressive lens, also known as the invisible bifocal. This distortion is found on both sides of the lens and is caused from blending your distance and reading prescription together amongst the height of the lens. The fabrication of these lenses takes into account how they are positioned in front of your eyes when in the frame, to provide the most accurate lens power and the sharpest vision possible.

Bifocal Lenses - these lenses will be worn at all times to accomplish your daily activities. They are similar to the Progressive Lens as they contain your distance and reading prescriptions, however, they are not blended. In other words, a visible line will appear at the bottom inner corners of each lens, which will hold your reading prescription, and the rest of the lens will hold your distance prescription.

Computer Lenses - If you're experiencing eye strain or blurred vision during computer work it may be due to an inability of your eyes to remain accurately focused on your screen or because your eyes have trouble changing focus from your keyboard to your screen and back again for prolonged periods. These focusing problems often are associated with Computer Vision Syndrome (CVS).

Plano Lenses – If you don’t have a prescription but like to wear eyeglasses or want to change the appearance of their eyes using novelty (colored) contact lenses, then these lenses are for you. For this type of lens, no power or acuity correction is required. Another use for plano lenses would be for someone who may need a prescription in one lens in their spectacles, but not in the other. In this case the lens is simply a placeholder that does nothing, with equal parallel curved surfaces.

Transitions Lenses –Transitions are the lenses that go dark when you are exposed to ultraviolet (UV) rays. These lenses are designed to quickly adapt from clear indoors to fully dark in brightest sun. Remember, Transitions lenses continuously adapt to changing light so they’re always exactly the shade you need them to be.

Polarized Lenses – this type of lens will give you the ultimate protection from damaging UV rays from the sun. So, how does it work? When light bounces off of a surface, its waves tend to be strongest in a particular direction — usually horizontally, vertically, or diagonally. This is called polarization. Sunlight bouncing off a surface like water, a road, or metal will usually reflect horizontally, striking the viewer's eyes intensely and creating glare. Most polarized lenses in glasses are laminated with tiny vertical stripes that only allow vertically angled light to enter the wearer's eyes. Glare is eliminated because the horizontal light waves cannot bypass the vertical filter.

Mirrored lenses – a mirrored coating can also be applied to the lens. This type of lens is an alternative to polarization for UV protection. This mirrored coating deflects some of the light when it hits the lens so that it is not transmitted through the lens, making it useful in bright conditions; however, it does not necessarily reflect UV radiation as well. However, the color of the mirrored surface is irrelevant to the color of the lens. For example, a gray lens can have a blue mirror coating, and a brown lens can have a silver coating. A bonus of a mirror coating is that it does not get hot in sunlight and it prevents scattering of rays in the lens bulk.

High-Index Lenses – When it comes to having a high prescription the lenses will be thicker and more noticeable in your frame. If you want to eliminate the bulkiness, try lenses in a high-index material, which are made of plastic. They offer superior optics in a thinner, lighter lens. Aside from thinness of the lens, another advantage of high-index plastics is they’re strength and shatter resistance, although not as shatter resistant as polycarbonate.

Polycarbonate lenses - are lighter, thinner and more impact-resistant than regular plastic lenses, as they are shatter proof. They're great for safety glasses, sports eyeglasses and children's eyewear.

If you have any further questions please give us a call at 1 (888) 388-3334 or talk directly with one of our Customer Service Agents through our Chat Application.

 

Prescriptions

We know that reading a prescription can be hard at times. What do all those numbers on your eyeglass prescription mean? And what about all those abbreviated terms, such as OD, OS, OU, SPH and CYL? 

  • DV refers to distance vision
  • NV refers to near vision
  • OD refers to your right eye
  • OS refers to your left eye
  • OU refers to both eyes
  • SPH (sphere) refers to the amount of lens power, measured in diopters (D), and prescribed to correct nearsightedness or farsightedness.
  • CYL (cylinder) refers to the amount of lens power for astigmatism. If nothing appears in this column, either you have no astigmatism, or your astigmatism is so slight that it is not really necessary to correct it with your eyeglass lenses.

NOTE: The number in the cylinder column may be preceded with a minus sign (for the correction of nearsighted astigmatism) or a plus sign (for farsighted astigmatism) and it is crucial that you enter your prescription exactly how your doctor has written it. Cylinder power always follows sphere power in an eyeglass prescription.

  • Axis – Axis specifies the direction of the cylindrical power. The spherical (sphere) and the cylindrical (cylinder) are the power or amount of correction you require in order to correct your vision. Unfortunately, due to the complexity of the axis explaining the difference between them requires a course in optics, but we would be more than happy to answer any further questions by email or phone. In hind sight, the spherical is power in all directions of the lens and the cylindrical is additional power in only one direction of the lens. Lastly, the axis is defined with a number from 1 to 180.
  • Add - This is the added magnifying power applied to the bottom part of multifocal lenses to correct presbyopia (a description of presbyopia follows). The number appearing in this section of the prescription is always a "plus" power, even if it is not preceded by a plus sign. Generally it will range from +0.75 to +3.00 D and will be the same power for both eyes.
  • Prism - This is the amount of prismatic power, measured in prism diopters, prescribed to compensate for eye alignment problems. Only a small percentage of eyeglass prescriptions include prism.

NOTE: Due to the complexity of prisms Swift Eyewear will not fill any prescription with prism. We recommend that you talk to your local optometrist or optician.

If you have any further questions please give us a call at 1 (888) 388-3334 or talk directly with one of our Customer Service Agents through our Chat Application.