The Top 5 Things You Should Consider When Getting Eyeglasses

A prescription for glasses is similar to a prescription for medication. It must be written by a licensed doctor, it has an expiration date, it’s specific to the patient, and it can be filled anywhere. So where should you get your prescription filled? Does it matter? Does it matter who takes the necessary measurements (not specified on the prescription) and do you need those measurements at all? Take a look at some things you might not have known about glasses, and then you decide.

What Are Eyeglass Lenses Made Of?

Lenses are rarely, if ever made of glass anymore. It’s too heavy and the safety profile of other materials is much better. Weighing half as much as glass, the most basic of lenses are made from a plastic material, referred to as CR39. It was first used to reinforce fuel tanks in the B-17 bomber in World War II, but is now the least expensive material used to manufacture eyeglass lenses. So why not use CR39?

Polycarbonate and Trivex are yet lighter weight materials used to makes lenses, and they are shatter-resistant. For children and adults with a more active lifestyle they are a must. And for those with a weak eye (a lazy eye or an eye with reduced vision due to injury or disease), the use of these protective lens materials is imperative. Although both polycarbonate and trivex create thinner and lighter lenses, the optics and therefore vision can vary with them. An optician (a professional who makes and fits glasses) will preferentially choose one over the other to provide the most comfortable vision, depending on the type of prescription a patient wears.

And then there are the high index lenses that are yet thinner and lighter than all of the other materials. These typically come at a greater cost, but the optics and reduced weight are superior to other options.

So how do you know which material to choose? You don’t really, without the experience and training of an optician to guide you. Opticians also take into consideration the type of frame you’ve chosen and the lens treatments and coatings you’ll need when selecting a lens material.

Lens Treatments and Coatings…. What’s All of That About?

• Glare from street lights and headlights with night driving• Glare from fluorescent lights in a school or grocery store• Glare and tired eyes from using a computer monitor all day• Glare off the front of your lenses to prevent your colleagues from making eye contact with you• Glare with your cataracts that aren’t quite ready for surgery

These are all reasons why no eyeglass lenses should ever be made without an anti-reflective coating. Some coatings peel (the bad ones) and thus create a bad name for these lens treatments, but the good ones provide infinitely better vision and visual comfort. They also provide a scratch warranty. There are many anti-reflective products on the market. Some are designed for computer users, filtering out the near-blue wavelength of light emanating from the screen, to protect your eyes from this light, thought to play a role in macular degeneration and sleep cycles. Others coatings are great for driving or problems with smudging. Experience tells an optician which one is best for a patient. Other lens options include UV coating, tint, anti-fogging, polarization, photochromic features and scratch protection. And not all options are available in all materials and lens designs.

What About Lens Designs?

A lens is a lens is a lens, right? Wrong. A single vision lens (i.e. for someone who is near-sighted only) can be digitally enhanced for better vision, particularly for large prescriptions and when used in frames that are wrapped or have a curve to them. There are many types of bifocals, trifocals, and progressives. Selecting the appropriate lens design is perhaps the most important decision that will have the greatest impact on how well you see in your new glasses. The distance to and position of your computer monitor on your desk, whether you use a laptop or a desktop computer, how much time you spend driving, how tall you are, and whether you have any issues with vertigo or motion sickness are all deciding factors as to the appropriate lens design.

The Magic Measurements

If you’ve ever gone online to peruse the montage of available eyeglass options, you’re probably familiar with the term Pupillary Distance or PD. Your PD is the number that determines where the horizontal center of a lens is placed in your glasses. Since we’re all unique, some of us with eyes closer together than others, this is not a one-size-fits-all kind of number. What happens if your PD is mis-measured? Well it depends on the prescription: You could be looking through increased astigmatism and a stronger or weaker prescription than prescribed by your doctor. The end result: Eye strain and blurred vision. This is why it’s best not to become your own optician, measuring your own PD, as is often the case when ordering your glasses online. So why doesn’t the optician in your eye doctor’s office give you this measurement? The company or person making your glasses is responsible for taking this measurement. It’s a part of lens design. Providing this measurement makes the optician responsible for the outcome of your glasses, a process over which he has no control.

Other measurements like where the bifocal should start in your lens (not too high as to interfere with your driving vision, and not too low as to be uncomfortable for reading) are critical to your success in a bifocal.

One more thing about lens measurements as it relates to your frames; Big is in. People love big frames, a trend largely started by Ray-ban, but popular throughout the industry. Very rarely does a large frame sit on your nose such that your pupil is in the geometric center of the frame (usually most of the lens sits below your pupil and you look through the upper third of the lens). These larger frames make assessing the vertical position of your pupil imperative to good comfortable vision, especially those with larger prescriptions, astigmatism, and prism. This is a measurement easily and frequently made by an excellent optician sitting across from you, while you wear the frame.

And At Last…Your Frames

The shape and size of a frame will affect how your lenses will look in it and how you will see with it. Smaller, round frames are best for prescriptions with a lot of near-sightedness. Large frames in general are not ideal for single vision lenses. They create more distortion in the periphery of the lens and they often result in thicker, heavier lenses despite the use of thinner materials. A larger frame (but not too large) is ideal for a bifocal or progressive lens. It insures there is enough room for each of the prescriptions your doctor has prescribed for you (distance, your computer, and/or reading).

What about frame design? A completely rimless frame, where the lenses are drilled and mounted to the temples (arms) of your frame is a nice option for a "barely there" look, but if not done with the proper lens material, your lenses will crack. Additionally, this design is not ideal for larger prescriptions, whereby a full plastic frame better hides the thickness of the lens.

What about nose pads? If you wear anything other than a single vision prescription, nose pads can be your best friend, as they allow the optician to adjust your glasses more readily, to insure that you’re looking through the appropriate part of your lens for the task at hand. There is little room for adjustment of a frame’s position on your nose, in a plastic frame without nose pads.

That’s a lot to think about for a simple pair of glasses! The good news is that a trained optician, sitting in front of you, able to assess your prescription, the activities you do on a daily basis, the history of your eye health, the fit of the frame you’ve chosen together, the position of your eyes in the lenses, and able to take accurate measurements can do all of the thinking for you. So why, if all of these things matter, didn’t you have to make these decisions when ordering online or at a large retail optical? Because someone likely made them in a one-size-fits all manner for you, at a corporate level. This is also why you can find glasses online for next to no cost; there is no optician employed to make these important decisions. As you can see, one-size DOESN’T fit all, and your glasses should be custom-tailored to you.

Last thing: The American Optometric Association conducted a study to look at the accuracy of glasses that were ordered online. Prescription, material, measurements, and safety standards were assessed. An astounding 44.8% of the glasses ordered failed inspection and were made incorrectly. Furthermore, 29% of children’s glasses failed impact testing. Any parent with a child in glasses, should find this alarming, considering the number of times their child has come home with broken frames. The last concern you should have is that the lenses designed to protect your child’s eyes were the cause of injury when they shattered.

Trust your eye doctor and your local optician to help you make the important decisions when it comes to your eye care and eyewear and enjoy clear, comfortable and safe vision for years to come!

Please visit our office for an eye exam or to fill your eyeglass prescription. We have a large selection of frames for adults and children, and our staff is knowledgeable in the many different lens and frame designs available to meet your needs. We offer convenient evening and weekend hours and a convenient location for those looking for eye care and eyewear in Wellington, Lake Worth, and the surrounding areas.