When buying spectacles, one usually spends a lot of time in choosing that right frame which sits well on the face, suits one’s style, etc. However, vision correction happens through the lenses which we finally choose. Therefore, understanding the basic characteristics of lenses for our vision correction is an imperative for spectacle wearers.
There are a lot of factors that need to be considered while choosing the lenses for your glasses and can influence your look, comfort, vision and safety. Take time to figure out your needs and accordingly make a wise choice in terms of lens design, material and coatings that offer suitable features. The following guide that explains various types of lens materials and coatings should help you pick the most suitable ones:Types Of Lens Materials:
- Glass- Glass lenses offer great vision but can break and are heavy. This makes them less friendly to use.
- Plastic- They are much lighter in weight than glass lenses and offer excellent optics. As a result, they are widely used today.
- Polycarbonate- This is another light weight lens option but comes with a higher impact-resistance. It is mostly preferred for safety and sports eyewear.
- Trivex- It comes with similar impact-resistance like that of a polycarbonate but has a higher Abbe value.
- High index plastic- A demand for lighter and thinner lens led to the making of these lenses. They come with a higher index of refraction and are lighter and thinner than CR-39 plastic lenses.
- Index Of Refraction A lens material is said to have a high refractive index if light passes slower through it, resulting in higher bending (refracting) of light rays. The more efficiently it bends light, the higher the index of refraction. Lenses with higher refractive index need less lens material and are thinner than those with a low index. So, CR-39 lens will be the thickest lens while high index plastic that has a reflective index of 1.74 will be the thinnest.
- Abbe Value Depending on the ability of a lens material to widely disperse different wavelengths of light as it passes through it, the Abbe value is determined. If a lens has low Abbe value it will result in an optical error where a coloured halo is seen around objects and lights. Crown glass lens has higher Abbe value than polycarbonate which has as low as 30.
- Aspheric Design Aspheric design lenses are slimmer in size and offer high index of refraction. Since, these lenses cause less magnification of the eye when worn, they make a better choice if your criteria is appearance. They are also known to provide better peripheral vision.The eye glass frame you pick will also determine the thickness of your lens irrespective of the lens material you choose. So, for a slimmer and lighter lens, pick a thin rimmed, petite frame.
The following coats and treatments become necessary, depending on your lifestyle and usage of your spectacle. Once you have decided which lens material and frame to choose, go for one or a combination of available coats for increased comfort, durability and aesthetics:
- Scratch resistant coat- Almost all the lens materials are prone to scratches, even from dust abrasion. Therefore, it is essential to give them a scratch resistant coat for durability.
- Anti-reflection coat- It is an ideal coat that is essential for all eyeglasses as it reduces glare, reflections and halos. It is beneficial for using digital screens and also while driving at night.
- UV-blocking- UV rays are known to cause age-related eye problems like cataracts and macular degeneration. A lens with UV protection like Vision Express UV Blue Shield helps block the harmful UV rays from affecting the eyes. <https://www.visionexpress.in/spectacles-lens>
- Photochromatic - These lenses adapt to lighting conditions indoors and outdoors. They darken when exposed to UV rays and get back to normal when indoors. They are ideal for people who do not want to opt for prescription sunglasses and want their spectacles to act as shades, when out in the sun.
Along with this guide, your optical retailer will also help you choose the best lens for your glasses after evaluating what best benefits you. Schedule a visit to your nearest Vision Express store to get a new pair frame fitted with the best lenses around for you!