Which are the best lenses for your glasses?
Lenses come in many variations and at times can be confusing. But don’t worry, we are here to explain them all in detail so that you can understand and choose the best lens option for you.
Firstly lenses can be made in two materials Organic (Plastic) or Mineral (Glass). Most lenses sold today are of the Plastic variety as they are far lighter than glass and safer due to strength and shatter resistence. Most people think that when we say a 1.6 lens that this means it is going to be 1.6mm thick, this is wrong. Basically the higher the number the thinner the lens will be.
Standard Plastic CR39 (1.56)
Ideal for most prescriptions (Prescriptions with powers stronger than +3.00 and -3.00 will start to look thick, powers between the two will look fine).
An ideal option for prescriptions up to +5.00 and down to -5.00. 1.6 lenses are 23% thinner than standard plastic. Prescription outside this range will start to look thick.
Probably the most popular of the thinner lens options. 15% thinner than the 1.6 and 25% flatter. Ideal for prescriptions up to +7.00 and down to -7.00 prescription outside this range will look thick.
The thinnest plastic lens available on the market. 50% thinner than the 1.56 standard plastic and 30% lighter than the glass equivalent. Great for mid to high prescriptions.
An ideal budget thin lens for “-“ power prescriptions up to – 10.00. However, they will be heavier than plastic
There are also many different styles of lenses. Lenses for single vision correction e.g., distance or reading to Bifocals and Varifocals for the correction of both distance and reading within one pair of glasses.
Varifocals blend gradually from your distance prescription trough your intermediate prescription in to your reading prescription. This means that the lens has to be set at exactly the correct height in the frame to start with. The crucial measurement required to align varifocals is the height in millimetres from the centre of your pupil to the bottom of the new frame, this measurement cannot be taken online.
Bifocals are basically distance glasses with a reading segment in the bottom. Unlike Varifocals Bifocals are commonly sold online as the height measurement is far less crucial and averages can be used with great success. Due to the fact that there is no gradual phase from distance into reading and they are just distance with a reading segment Bifocals have a far wider corridor for reading than Varifocals but have no intermediate correction.
“Single Vision” lenses can be used for Just distance, just intermediate or just reading hence the name “single vision”. However, many people who are short sighted “-“ Power SPH prescriptions will be able to read with their distance glasses. Single vision lenses are available in both materials and all indexes.
Tints, Photochromic’s & Anti reflective coatings.
Tint’s can be used to make “Plastic” lenses in to sunglass lenses and are available in many colours. However, 1.67 and 1.74 lenses cannot be tinted as they already contain an antireflective coating to reduce “Power rings” which I will explain later.
Photochromic’s are usually referred to as “Reactolite” which is a brand name for the glass variety or “Transitions” which is a brand name for the plastic variety. Basically they do the same thing. These are lenses which are clear indoors but then “react” to UV (Sunlight) and “transform” into sunglasses.
NOTE: As photocromic lenses require UV to change, using them behind a car windscreen will not work as effectively as normal due to the windscreen filtering out some of the UV. However, we have found that the glass reactolite works better than the plastic behind a car windscreen, but not as good as the plastic in normal conditions.
Usually an anti reflective coating is referred to as an “MAR” (Multi Anti Reflective Coating). There are many benefits to an MAR. Firstly they are far more aesthetically pleasing as they reduce the amount of light reflecting off of your lenses especially when having your photograph taken.
Other benefits include:-
• Reduced glare when driving at night
• People can see your eyes and not a patch of light
• Filters out radiation from computer screens
• Reduces “Power rings” visible rings on the lens in high prescriptions which is caused by light constantly bouncing back and forth within the lens due to total internal reflection.
• Provides UV protection
• Antistatic aiding lens cleaning
We hope this guide has helped to give a better understanding about the various types of lenses available. If you found this guide helpful, please vote 'yes' below.
Designer Eyewear 4u Team