Thinner Lens Options

Our standard thickness lenses are made of a plastic known as CR39, which has been the standard lens material for glasses for many years. CR39 lenses are half the weight of glass lenses. Also, high quality coatings, such as Crizal Forte UV, applied to plastic lenses offer scratch-resistance equivalent to glass.

Thinner lenses, known as high index lenses, are thinner and lighter than regular CR39 plastic. For a given prescription and frame design, the factor which determines lens thickness is the refractive index of the lens material. Material with a high refractive index bends light more than material with a lower refractive index. CR39 material has a refractive index of 1.5. Material with a refractive index above 1.5 is considered a high index material. Our high index plastic lenses are available as 1.67 and 1.74 index. We also offer polycarbonate lenses (1.59 index) which are 10 times more impact resistant than regular plastic lenses.

In addition to the refractive index of a lens, final lens thickness is determined by a number of factors including:

• Your prescription
• Your pupillary distance (PD)
• The shape of the lenses
• The size of the lenses (both vertically and horizontally)
• The bridge size of the frame
• The lens design

Please contact us with your prescription, PD and preferred frame if you would like us to calculate the maximum thickness of your lenses.

The majority of single vision lenses we fit are pre-moulded to a specific prescription. These are known as “stock” lenses, and our glasses prices reflect the value that these lenses offer. However, stock lenses are not suitable for certain prescriptions in rimless and semi-rimless frames as the resulting edges are too thin ( a minimum edge thickness of 2mm is required for these types of frame). In such circumstances, specially made lenses, known as “surface” lenses are required. Surfaced lenses are priced differently to stock lenses due to the additional work involved in their manufacture. Surfaced and stock lenses are of equal visual quality.

We only recommend surfaced lenses where stock lenses are not suitable, as we always discuss the options with our customers prior to processing orders. Our surfaced lens supplements are as follows:

^*Surfaced lenses include Crizal Easy UV, anti-reflection, scratch-resistant coating as standard. The 1.74 index lenses include the Crizal Forte UV coating as standard.