Products

Introducing SINGLE VISION

Single vision has the same optical focal point or correction over the entire area of lens.

Refractive Index

In the UK, the refractive index is generally specified with respect to the yellow He-d Fraunhofer line, commonly abbreviated as nd. Lens materials are classified by their refractive index, as follows:

Normal Index - 1.48 =nd < 1.54

Mid Index - 1.54 =nd < 1.60

High Index -1.60 =nd < 1.67

Ultra high index- 1.74 = nd

This is a general classification. Indexes of nd values that are = 1.60 can be referred to as high-index. Likewise, Trivex and other similar materials may be referred to as mid-index.

Advantages of higher indexes

  • Thinner and lighter lenses.
  • The higher the index, the lighter and thinner the lenses become.
  • Improved UV protection over CR39 and glass lenses.
  • Flatter lenses compared to 1.50 index.

Disadvantages of Increased Indices

The only disadvantage is that high index lenses have lower Abbe values meaning, amongst other things, increased chromatic aberration.

However with the advancement in lens treatments, this aspect can be taken care of.

Material Plastic

Index
ABBE
Specific Gravity (gcm3)
UVB/UVA
Reflected Light(%)
Minimum Thickness type/min (mm)
CR-39 Hard Resin 1.49 59 1.31 100%/90% 7.97 ?/2.0
Trivex
(Average)
1.53 44 1.11
100%/100% 8.70 ?/1.0
Mid Index 1.54 47 1.21 100%/98% 8.96  
1.56 1.56 37 1.23 100%/100% 9.52  
Polycarbonate 1.586 30 1.20 100%/100% 10.27 ?/1.5
Crown Glass 1.525 59 2.54 79%/20% 8.59  
photogrey Extra 1.523 57 2.41 100%/97% 8.59  
1.60 Glass 1.604 40 2.62 100%/61% 10.68  
1.70 Glass 1.70 30 2.93 100%/76% 13.47  
1.80 Glass 1.80 25 3.37 100%/81% 16.47  
1.90 Glass 1.893 31 4.02 100%/76% 18.85  

High-Index eyeglass lenses are the right choice if you want thin lenses or glasses that are as attractive and comfortable as possible.

Thinner, lighter high-index lenses are especially recommended if you have a strong prescription for nearsightedness, farsightedness or astigmatism.

Most of today's fashionable frames are made of plastic or metal with rims thinner than the lens itself. Rimless mountings are also popular and require that the edges of the lenses are completely exposed. In either case, the lens edges are highly visible and thicker edges can detract from the appearance of your eyewear.

Eyeglass lenses correct refractive errors by bending light as it passes through the lens. The amount of light-bending ability (lens power) that is needed to provide good vision is indicated on the prescription provided by your eye doctor.

Refractive errors and lens powers required to correct them are measured in units called dioptres (D). A typical nearsighted prescription might read -2.00 D. If you are highly myopic it might read -8.00 D. If you are far sighted, you need plus prescription lenses which are thicker in the centre and thinner at the edge.

AVAILABILITY IN SINGLE VISION

INDEX
Clear
Color
Power Range
1.74 Plastic Clear -18.00D/ +10.50D
1.67 Plastic Clear -17.00D/ +17.00D
1.60 Plastic Clear -12.00D/ +10.00D
1.59 Polycarbonate Clear -12.00D/ +9.00D
1.53 Trivex Clear -10.00D/ +7.00D
1.50 CR 39 Clear -10.00D/ +11.00D
1.50 Biconcave Clear -10.00D/ +16.00D
1.56 Biconcave Clear -10.00D/ -18.00D
1.50 Lenticular CR 39 Clear -16.00D/- 10.00D, +8.00D/ +4.00D
1.50 Omega CR 39 Clear +8.00D/ + 14.00D
Transitions
Clear
Color
Power Range
1.74 Plastic Grey/ Brown -18.00D/ +10.00D
1.67 Plastic Grey/ Brown -14.00D/ +8.50D
1.60 Plastic Grey/ Brown -12.00D/ +8.50D
1.59 Polycarbonate Grey/ Brown -10.00D/ +8.00D
1.53 Trivex Grey/ Brown -8.00D/ +8.00D
1.50 CR 39 Grey/ Brown -10.00D/ +8.00D
Transitions Xtractive
Clear
Color
Power Range
1.67 Plastic Grey -12.00D/ +7.00D
1.60 Plastic Grey -12.00D/ +8.00D
1.53 Trivex Grey -8.00D/ +8.00D
1.59 Polycarbonate Grey -10.00D/ +8.00D
1.50 CR 39 Grey -10.00D/ +8.00D
Polarised
Clear
Color
Power Range
1.67 Plastic Grey/ Brown -13.00D/ +8.00D
1.60 Plastic Grey/ Brown -13.00D/ +8.00D
1.53 Trivex Grey/ Brown -8.00D/ +8.00D
1.59 Polycarbonate Grey/ Brown/ Grey/ Copper -10.00D/ +8.00D
1.50 CR 39 Grey/ Brown -8.00D/ +8.00D
Drivewear
Clear
Color
Power Range
1.50 CR 39 Brown -10.00D/ +8.00D
1.59 Polycarbonate Brown -10.00D/ +8.00D
Sunlite
Clear
Color
Power Range
1.56 Plastic Grey/ Brown -12.00D/ +10.00D
Acclimates
Clear
Color
Power Range
1.50 CR39 Grey/ Brown -10.00D/ +8.00D
Mineral
Clear
Color
Power Range
1.90 Glass White -24.00D/ -4.00D
1.80 Glass White -24.00D/ -4.00D
1.70 Glass White -24.00D/ +8.00D
1.60 Glass White -10.00D/ +8.00D
1.60 Glass PGX/ photobrown -10.00D/ +8.00D
1.52 Glass White -10.00D/ +8.00D
1.52 Glass PGX/ photobrown - -10.00D/ +8.00D
MAX +6.00 CYL