Spectacles lenses:

When it comes to buying lenses, there are a variety of brands and lens material available in the market. With this understanding of lenses, it will be really easy for you to make a correct decision on what lenses are best suited for your prescription. Choose wisely to make your glasses cosmetically appealing and comfortable to use.

We will explain the different types of eyeglass lenses and any add on for prescription eyeglasses:

 

Standard Lenses – Conventional Lenses

Aspheric Lenses – Thinner and Flatter Lenses

Thin and Light Lenses – Also known as Hi-index Lenses.

Light Weight Polycarbonate Lenses – Special Safety Lenses

Bifocal Lenses – For Multiple Vision Correction.

Progressive Lenses – For Multiple Vision Correction Upgrade.

Transition Lenses – Special Lenses with Enhanced Performance. Can be used as Sunglasses and Regular Glasses.

Polarized – Special Lenses for Sun Protection

 

Add On:

Anti-Scratch Coating – Also referred to as Hard Coating

Anti- Reflective Coating – Also referred as Anti-Glare Coating

Tinting – Colored Prescription Eyeglass Lenses for Sunglasses

 

Standard Lenses:

Standard lenses are made of plastic CR39 and has an index of 1.50. These lenses are most suited for all prescriptions. Plastic lenses as these are lighter and safer. These lenses are highly recommended for standard prescription up to +/- 3 SPH and CYL up to +/- 2.

 

Aspheric Lenses:

These lenses are the next step and the design is an important upgrade to that of the standard lenses. This provides better vision and more clarity. As compared to standard lenses, these lenses are designed to be thinner, flatter, which as a result offers aesthetic and cosmetically appealing glasses. Aspheric lenses are available from 1.56 index and all hi-index lenses are aspheric in nature.

 

Hi Index Lenses:

A prescription lens requires two properties - the refractive index of the lens and the curvature. When the lens has a higher refractive index, it can bend more light and thus curvature can be minimum leading to thinner lens.

High index lenses are now made using glass or plastic depending on the need. When the material has high index of refraction, the composition of the lens will be dense which means material used to make the lens would be significantly less which ultimately leads to thinner lenses. The higher the refractive index of the material, the thinner is the lens made out of it.

 

Below are the lists of Index available:

1.60 Hi-Index lenses: are up to 30% thinner than conventional plastic lenses. These lenses are beneficial for people who want thinner, flatter and lighter lenses for cosmetically appealing eyeglasses. 1.60 Hi-index lenses offer superior quality of vision due to its aspheric design which will reduce peripheral distortion.

These lenses are recommended for prescription above -3.00 and below -6.00 for thinner and lighter eyeglasses.

 

1.67 Hi-Index Lenses: are up to 40% thinner than conventional plastic lenses. These lenses are beneficial for people who want thinner, flatter and lighter lenses for cosmetically appealing eyeglasses. 1.67 Hi-index lenses offer superior quality of vision due to its aspheric design which will reduce peripheral distortion.

These lenses are recommended for prescription above -5.00 and below -11.00 for thinner and lighter eyeglasses.

 

1.74 Hi-Index Lenses: are up to 50% thinner than conventional plastic lenses and are the thinnest lenses available in plastic lenses. These lenses are highly beneficial for people who want thinner, flatter and lighter lenses for cosmetically appealing eyeglasses. 1.74 Hi-index lenses offer superior quality of vision due to its aspheric design which will reduce peripheral distortion.

These lenses are recommended for prescription above -8 for thinner and lighter eyeglasses.

Higher index like ultra thin 1.9 index lenses are also available in glass so that they can be made thinner. But due to its fragile nature glass lenses are not recommended for prescription eyeglasses. Generally plastic lenses are more suitable as these lenses are lighter and safer as compared to glass lenses.

 

Light weight polycarbonate lenses: are 1.6 index lenses which are thinner and lighter than conventional lenses. These lenses are 12 times more impact resistant than conventional plastic CR39 lenses and 40 times more than conventional glass lenses. Due to its impact resistant properties these lenses are highly recommended for children, sports person and with rimless frames.

 

Bifocal Lenses: provide clear vision for two different ranges, usually for distance and near vision but can also be made intermediate (computer vision) and reading. There are different varieties of prescription bifocal lenses available and below are the different designs and its name for bifocal eyeglasses available.

 

Executive bifocal eyeglasses: Executive bifocal has a prominent line running across the lenses which divides the lenses into two halves. The upper portion of the lenses is completely dedicated for distance vision and lower half of the lenses can be used for reading.

 

Kryptok Bifocal Eyeglasses: Unlike executive bifocal where there is a line dividing the lenses, kryptok bifocal has a 28mm semi-circle at the bottom of the lenses. Theses lenses are more cosmetically appealing as compared to executive bifocal as the reading portion of the lenses are not completely visible due to its design thus the onlookers will not notice the reading portion easily.

 

Flat Top Bifocal Eyeglasses: Flat top bifocal eyeglasses are similar to Kryptok bifocal eyeglasses in terms of design but the only difference is instead of a complete semi-circle at the bottom of the lenses the upper portion of the semi-circle are cut straight thus the reading portion of the lenses look like a rectangle with curved sides. As compared to kryptok bifocal lenses the reading portion of the lenses are clear visible.

 

Progressive Lenses: Unlike other lenses, which offers mono vision correction or bi-focal correction (Distance and Reading), progressive glasses are designed to offer three different vision zones. They are categorized as near, intermediate and far vision. Thus these lenses are not restricted to specific zones like other lenses which make the person's vision smooth. These different vision zones are embedded on the lenses and the design may vary according to the manufacturer.

Progressive eyeglasses are much more cosmetically appealing as compared to bifocal eyeglasses. Bifocal eyeglasses have an uncomfortable dividing line separating the distance and reading zone, thus the onlookers can easily identify that your glasses are multi-focal. With progressive lenses the lines do not exist on the lenses and the glasses appears as a single vision glasses.

 

Transition lenses: also known as photochromatic lenses are almost clear when indoors and automatically darken when exposed to sunlight. These lenses have silver chloride or silver halide embedded in them which undergoes a chemical process when exposed to direct sunlight or UV rays (please note that these lenses do not change color while sitting behind car windshield and the windshield are coated with UV filters).

The main advantage of theses lenses is that you do not have to carry a separate pair of sunglasses to protect your eyes against harmful UV rays.

 

Polarized Lenses: has thin laminated surface attached on the lenses that helps eliminate glare from reflective surfaces such as the surface of a lake or the hood of a car. Polarized glasses are generally used by sailors and fishermen to reduce glare from the water. Recently it has gained its popularity among people who drive, who are actively participating in outdoor activities and sports enthusiasts. Thus polarized lenses are available in different colors, lens materials and lens types.

 

Add On:

Anti-Scratch Coating: is a coating that can be applied to the surface of the lenses. This coating doesn't affect how the lenses functions and doesn't interfere with your vision, but helps protect your lenses from getting scratches easily. No lenses, even glass lenses, are scratch proof thus it is important that you follow the instructions on "how to clean eyeglass lenses?"

 

Anti- Reflective Coating: is a coating of several ultra-thin layers applied on the surface of the lenses. Normal eyeglass lenses causes reflection. These reflections create hazy, fuzzy, ghost image, and halos that interfere with your vision. The reflection of the lenses make it harder to see – especially while driving, working on the computer, watching TV or working under florescent lights. Anti-reflective coating eliminates lens reflection so you can have a clearer and crisper vision that is not possible with standard lenses. This coating also makes your lenses more transparent and your spectacles more conspicuous and more attractive.

 

Tinted Lenses: 

Date: Nov 20th 2010