If you thought that fashion was fast-changing, then you might be in for a shock; spectacle lens design is no different. New materials, designs and coatings are announced by laboratories to the optical profession almost weekly.
One of the biggest changes over recent years have been the introduction of higher index materials. These are materials with a refractive index higher than 'standard' glass or plastic lenses. Using such material in spectacles leads to a thinner lens.
One area of lens technology where there is ever-continuing development and improvement is the design of progressive addition lenses (also known as multifocals or vari-focal lenses). Patients are often amazed at the number of different progressive lenses available. Most manufacturers make a whole series of designs; from ‘budget’ lenses (often based on older designs) to highly customised
lenses with far superior optics. Progressive lenses start life as a complex set of equations plotting the constantly varying changes in curvature over the surfaces of the lens. It was the advent of computer-controlled surfacing equipment that led to the improved optics of the modern progressive lens. This is area of development where the mathematicians develop new designs before the technology exists to turn the equations into reality! Although most people need a progressive lens to cover all distances from infinity to close-up, this isn’t necessarily the best solution. Some of the latest research has led to types of lenses known as ‘occupational’ progressives. These are specifically aimed at intermediate and near use, and some of these can be the perfect solution for those of us who spend most of our time using computers, offering a much wider field of view than regular progressive lenses.
The very latest spectacle lens advance has been the ability to ‘tailor’ the optics of your spectacle lens to an incredible level of accuracy. One of our latest pieces of equipment is a device that enables us to take highly detailed facial measurements, also taking into account the way your frame fits, and the way your eyes rotate behind the frame of your choice. This enables lenses to be made to an incredible level of customisation resulting in extremely accurate vision.
Like any precision-made optical device, your lenses will need to be looked after correctly if you are to get the best from them. A little time spent looking after your lenses can add years to the ‘life-expectancy’ of your spectacles! Click here for some advice about looking after your lenses.
Further information about modern lenses can be found at the various manufacturers' sites on our links page... just remember that manufacturers can find it hard to be unbiased about their own lenses. It's always worth checking with an independent optician before making up your mind about that new pair of hi-tech lenses!
With continuing research into lens design, the use of carefully calculated aspheric surfaces in conjunction with higher index materials makes a lens even thinner, flatter and lighter. Most quality lens laboratories now use both methods, sometimes in conjunction to create lenses that not only correct vision more effectively, but look more attractive also.
Another way to improve the optical performance of any lens is to incorporate an anti-reflective coating. These coatings have been available for several years, but recently the quality has improved dramatically - many are now more durable than a basic lens and are much easier to clean than previous types. These coatings are used on spectacle lenses for the same reason that they are used on cameras, binoculars and other pieces of optical equipment; they improve the transmission of light by reducing front and back surface reflections.
This leads to a 'crisper' image with a higher image contrast and much reduced reflection from the lens surface. The improvement in vision is noticeable in nearly all situation but the most dramatic improvement occurs at night when annoying reflections and 'ghost-images' from lights can be a real distraction with uncoated lenses - particularly when driving. You won't find many opticians wearing lenses without an anti-reflective coating!