Once you have had your eyes examined, if you need glasses or if you require a spare pair of glasses, Karen our expert dispensing Optician will explain all the different types of lenses available with their advantages and disadvantages. Broadly speaking there are two main types of lens materials:
1. Glass – also known as mineral
Advantages
- Don’t scratch
- Can be the thinnest lenses in high index material (n =1.9 for extremely high minus prescriptions)
Disadvantages
- Heavier than plastics
- Can break or chip more easily, therefore less safe
- Photochromics don’t have uniform tint and take much longer to fade
- Hard to tint
2. Plastics – also known as CR39 n=1.5, high index plastics n=1.6, n=1.67,n= 1.74 polycarbonate n=1.61, trivex™ n=1.53
Advantages
- Lighter in weight
- Can be made thin in higher refractive materials
- Can be made in rimless and supra (semi-rimless) frames
- Photochromics have uniform tint (in any prescription) eg Transitions®
- Safer – especially polycarbonate and trivex material
- Easy to tint
Disadvantages
- Easier to scratch (we recommend anti-scratch/anti-reflection coatings)
- More expensive in the very high index materials and photochromic materials
Single Vision Lenses
Advantages
- Relatively inexpensive
- Give the largest field of vision
- Can be made in virtually any prescription
Disadvantages
- Not good if more than one correction is required (e.g. distance and near or glasses for computer)
- Easier to lose or break because constantly taking them on and off
Multifocal Lenses
1 Bifocals and Trifocals
2 Varifocals (also known as progressive or PAL)
3 Occupational lenses
Advantages
- Can be used for all required distances
- Can be combined with tints or coatings
Disadvantages
- Can take longer to adapt
- Some prescriptions are not recommended (e.g. where the two eyes are very unequal)
Some of the companies we use at the Village of Optician Ltd and their websites are listed below
Essilor the worlds most famous varifocal lenses come from this company
BBGR quality lenses from a local company
Other useful websites
Transitions ® Photochromic plastic lenses
