Just as the selection of eyeglass frames has advanced and expanded, so have the options available for eyeglass lenses. What used to be a simple choice between glass or plastic now involves a number of different features to consider.
To assist you as you decide between all the various eyeglass lenses and their features, here is a detailed explanation of the available lenses:
High Index Lenses for a Thinner Look and Greater Comfort
Lightweight and ultra-thin, high index lenses will enhance every pair of eyeglasses. These lenses are especially helpful for strong prescriptions, yet they will create a noticeable difference in almost every degree of vision correction lenses. High index lenses are thinner because they need less lens material to sharpen your vision, due to the material’s ability to bend light more efficiently than standard plastic or glass lenses.
Lenses with a higher index of refraction (also called “refractive index”) will generally be thinner and more costly than lenses with a lower index. Regular plastic lenses have a refractive index of 1.50, while high index plastic lenses range from 1.53 to 1.74. What this means is when high index lenses are between 1.53 and 1.59, they are about 20% thinner than regular plastic lenses. Once you reach numbers like 1.74 high index lenses, they are approximately 50% of the thickness of regular plastic lenses! Rule of thumb is that the higher the index of refraction, the thinner and more comfortable the lenses will be.
High index lenses reflect a greater quantity of light than regular lenses. So when it comes to high index lenses, it’s strongly recommended to add an anti-glare (AG) component to the lenses.
The vast majority of lenses are available in high index materials, whether you need single vision, progressive, or photochromic eyewear. Ask your eye doctor or optician which specific lenses are available in your prescription. Bifocal and trifocal are also available, yet the array may be more limited.
Go Flat with Aspheric Lenses
Typical lenses have a rounded, spherical curve on the front surface. In contrast, aspheric lenses are curved in a way that the center of the lenses is flatter and changes gradually towards the periphery. The effect is to appear significantly flatter, giving your eyeglasses a more attractive lens profile. Note that this flatter lens may also result in more noticeable reflections, which is easily resolved with an anti-glare (AG) component.
Aspheric lenses aesthetically enhance all eyeglass prescriptions, yet they are especially valuable when you have farsightedness. They will diminish the magnified, bulbous look of regular lenses for farsightedness, and your lenses won’t bulge out of the frame as much. The slimmer lenses are naturally more lightweight, providing additional comfort. An additional bonus is that they enhance peripheral vision.
Polycarbonate and Trivex Lenses for Tough Performance
Polycarbonate and Trivex lenses are lighter, thinner and safer. Up to ten times more impact resistant than regular plastic lenses, they are both perfect choices for children. They also provide top function for safety eyewear and for adults who engage in sports or lead active lifestyles.
Polycarbonate lenses are about 25% thinner than standard plastic eyeglass lenses, with a refractive index of 1.59. They are up to 30% lighter than regular lenses. Anyone who doesn’t want to feel weight on their nose will find this feature particularly appealing!
While Trivex lenses may be a tad thicker than polycarbonate, they offer a similarly high level of impact resistance. With 100% protection from harmful UV rays, both materials are great outdoor options.
Anti-glare (AG) component: See and Look Better
Reflective glare bounces off all eyeglasses lenses, thereby affecting the quantity of light that enters your eye when viewing any images. This impacts your quality of vision, particularly in low light conditions, such as night driving. The amount of light that gets reflected is directly related to the type of lens material.
Conventional plastic or glass lenses reflect approximately 8% of light, so only 92% is left to enter your eyes for effective vision. With high index lenses, up to 50% more light is reflected by the thinner material. To allow more light to enter your eyes and solve this problem, anti-glare (AG) component of lenses is essential and recommended. No matter what material lenses you’re wearing, the AG transmits over 99% of available light to your eye for clear vision.
Anti-glare basically erases surface reflections, which makes your eyeglass lenses almost invisible. Your eyewear therefore looks better and gives others a better view of your beautiful eyes, instead of seeing just the reflections in your glasses.
Proper care of anti-glare involves using specialized products, as advised by your optician. AG do not hide any tiny scratches that would normally be less visible due to reflections, so it’s important not to scratch your lenses.
Scratch-Resistant Coatings Create Solid Lenses
Although no eyeglass lenses are totally impenetrable to minor scratches, a scratch-resistant coating will strengthen your lenses so that the occasional fall or rough wipe with a towel won’t etch the surface with little lines. Almost all high index lenses come with a scratch-resistant coating applied in the factory. This coating, added to the front and back of your lenses, is a wise investment for any adult or children’s eyewear. Only glass lenses will not benefit greatly from a scratch-resistant coating, as glass possesses this feature naturally.
When your eyeglasses are not on your face, a hard, protective case will preserve them well from scratches. For cleaning, proper care and handling of your lenses entails rinsing them first in water or a cleansing solution. Using a cloth or towel to rub dry lenses can scratch the surface.
Ultraviolet (UV) Treatment for Ultimate Safety
UV treatment in eyeglass lenses blocks the same harmful sunrays that sunscreen keeps from damaging your skin. In eyeglasses, this treatment provides targeted protection for your eyes and the delicate tissues surrounding them. Overexposure to UV light is associated with a higher risk of retinal damage and cataracts, among other eye conditions.
High index lenses generally have 100% UV protection incorporated into the lenses. Standard plastic lenses though need a special lens treatment, which doesn’t alter the appearance of your eyeglasses and is relatively inexpensive.
Photochromic Lenses Adapt to the Environment
Photochromic lenses darken automatically in response to outdoor sunlight and return quickly to their clear state when you go indoors. They are a convenient solution for eyewear that provides comfortable vision both outside and inside. With 100% protection from UV rays, they also promote eye health.
Photochromic lenses are available for a diversity of vision correction eyeglasses, including bifocals and progressive lenses. They come in a large array of designs and lens materials, and the degree to which they darken depends upon the level of exposure to UV radiation. However, photochromic lenses don’t darken sufficiently for driving because the windshield acts as a barrier to much of the sun’s UV rays. A pair of prescription sunglasses for driving or a sunglass-clip with your photochromic glasses is typically the best solution.