There are so many spectacle lens types around these days that it’s hard to know which are best for your own needs. Fortunately, all of the team at Julian May Opticians are well trained to guide you through the spectacle lens minefield and advise you specifically.
There are lots of different spectacle lens manufacturers: Essilor, Nikon, Zeiss, Norville, Rodenstock, Kodak, Hoya and various smaller lens laboratories. We select the best lenses from these suppliers and, in the vast majority of cases, fit them to your frames in our own on-site lab. In this way, we can ensure that your spectacles are finished to the highest standards.
In all aspects of the optical profession there is a lot of jargon and unfortunately this doesn’t stop with spectacle lenses! Below are some simple definitions of some of the more common terms used:
High Refractive Index (or High Index)
This refers to the material the lens is made from – generally speaking, the higher the refractive index, the thinner and lighter the lens becomes.
Often, spectacle lenses have surfaces that are spherical or are curved like a football. Aspherical lenses have surface curvatures that are elliptical or like a flattened football. This gives better peripheral sight when looking through the edge of the lens and makes the lenses thinner and neater looking.
Photochromic lenses go darker in the sunshine and become clear indoors. Transitions, Sensity, Photogrey, Photobrown and Reactolite are all makers’ names for photochromic lenses.
Bifocal lenses have two distinct sections – usually the top part of the lens is for distance use and the bottom section or segment is used for near.
Trifocal lenses have three distinct sections – usually the top is for distance, the middle section for intermediate (for computer use or reading music perhaps) and the bottom is for close work.
Varifocal lenses have a smooth change in lens power, usually with the top of the lens for distance and gradually changing to near towards the bottom of the lens. Early varifocal lenses suffered with a lot of distortion towards the periphery or edge of the lens but technology has improved this massively over the last few years.
Tints and coatings
Many lens types can be tinted in lots of different colours and to varying degrees of darkness. Certain colours are better for reducing glare or increasing contrast in different conditions and for different sports like cycling, fishing or golf.
Your lenses can be treated or finished with different coatings to make them more resistant to scratching, more transparent, easier to clean or to stop them fogging up.