There are many different options and materials that lenses are made from and all have different features and benefits depending on your needs and prescription.
This guide will help you to Choose The Best Lens for Your Prescription Glasses & Lifestyle:
Standard Lenses:
Are made from a plastic known as CR39. This is the type in which all inclusive frames are made with and are recommended if you have a low prescription typically less than +/- 2.00.
High Index Lenses:
Are made of a plastic material which bends light more than standard CR39 lenses and can therefore be made thinner and lighter allowing for more cosmetically appealing and comfortable to wear glasses.
There are three main high index lenses options called:
1.60 Index
1.67 Index
1.74 Index
The numbers are simply the names of the plastic and does not refer to the thickness of the lens as is often mistakenly assumed.
1.60 Index is on average 20% thinner than ordinary CR39 plastic.
1.67 Index is on average 35% thinner than ordinary CR39 plastic.
1.76 index is on average 50% thinner than ordinary CR39 plastic.
This example shows the difference in thickness for high index lenses.
Polycarbonate Lenses:
Are virtually unbreakable and offer a high level of shatter and scratch resistance and are used when a high degree of impact resistance is required such as for safety glasses, children’s glasses or for playing sport.
Photochromic Lenses:
Are often referred to by the trade name ‘transitions’ or ‘reactolights’.
Photochromic lenses react to light conditions. They are clear indoors but ‘react’ and turn dark into a sunglasses depth/shade when exposed to light or outdoors. They also offer a UV protection against harmful sun rays.
Polarised Lenses:
Are high-tech sunglasses lenses which block out horizontal glare and UV rays. They are excellent as sunglasses and can offer enhanced vision when driving or for sports such as fishing or skiing.
Visit the next chapter by clicking the link below:
Understanding Prescription Lens Coatings >>
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