Lenses

Single vision
This simplest type of lens, and the lowest cost, is often the best choice. Designed to bring vision into focus, single vision lenses correct myopia (short sight), hyperopia (long sight), astigmatism and presbyopia. For a person under the age of 40 with normal accommodation (eye focusing ability), a single vision lens is the common choice. An older person will need differing prescriptions to function for near (reading, sewing), intermediate (computer, music) or distance vision, making the choice of multifocal lenses attractive to avoid changing glasses.

Bifocal lenses
Combining different powers of lenses was Benjamin Franklin's invention. Modern bifocals have two lens powers moulded into them or two different refractive index glass materials fused together. By combining clear focus at two different distances, it isn't necessary for the wearer to change glasses when looking from reading to TV, or from the desk to the calendar on the office wall, but there is a small image jump as our vision crosses over the division line between the two lenses. Bifocal lenses give a wider field for reading, and better peripheral vision than progressive focus lenses.

Trifocal lenses
With another focus right in the middle, trifocal lenses give clear vision for distance, intermediate, and near. They're excellent for general vision when computers and music require good vision at arm's length. For librarians and others with similar needs, there are quadrifocals!

Progressive addition lenses (sometimes called graduated lenses)
Very complex curves on these lenses have been precisely generated to give continuous vision from distance to near. Though the reading section is limited in area, progressive addition lenses restore the most natural vision, with no image jump across the bifocal line. Though an adaptation period is required to learn to use these lenses, they are the best general purpose choice for most people who have lost their accommodation. There are many progressive addition lenses on the market. Some are excellent, some are poor, some are very specialized in their use and some newly designed lenses have increased the field of vision considerably. Our experience wearing progressive addition lenses will help guide you in the most suitable lenses for your requirements, and if progressives just don't work for you, we will change you to a bifocal at no additional cost.

Occupational progressive lenses (enhanced near vision)
These are specialized lenses designed to give a much wider field of vision for the computer and near vision. They are excellent in an office, or for music, and are often used as an additional pair of glasses for the person wearing a full progressive for their general vision. Occupational lenses should not be used for driving.

There is a vast range of lenses available in glass and plastic, thick, thin, single vision, multifocal, hardened, scratch resistant, multicoated; the list is endless.
Once we have identified the most appropriate lens for your special needs, we choose the best from the leading lens manufacturers in the world. We only use the highest quality lenses available, because your eyes deserve the best.

LENS MATERIALS and SPECIAL TREATMENTS

Many different materials are used for spectacle lenses, and each has its own benefits.

GLASS - still best for some prescriptions!

Though not used as widely now because they are heavier and can shatter in an accident, glass lenses have some excellent optical properties and are very resistant to scratching, though providing less UV protection. Special glass lenses are available with a very high refractive index, making them the choice for the thinnest possible lenses for high prescriptions. Hardening reduces, but doesn't eliminate, the risk of breakage.

PLASTICS - commonly used, with excellent UV protection. All our lenses are treated with scratch resistant coatings.

Standard plastic (CR39) is the most commonly used plastic material for low prescriptions. It is quite a hard plastic with excellent optical properties.

Mid to high index lenses are thinner, and increasingly the material of choice. Excellent optical properties combined with thinner lens profiles and lighter weight are much appreciated by our patients. Reflection free coatings are recommended on these lenses.

High index plastic lenses have taken a leap forward in recent years. Thin and light, they are ideal for high prescriptions, but must have reflection free coatings.

Polycarbonate material is very resistant to breakage, but vision isn't as good with higher prescriptions. It is damaged by certain cleaning chemicals. Useful for children and workers in eye danger industrial areas, but is not a preferred material for most patients.

Trilogy (Phoenix) is a new material combining the low breakage of polycarbonate with resistance to chemicals and reduced chromatic aberration. Ideal for rimless fitting!

Photochromic lenses change colour. In bright conditions they are quite dark, especially in colder temperatures, and are almost clear inside. Newer lenses by Transitions and Kodak change rapidly! Though widely advertised for use under all conditions, they have limitations.

Polarising lenses. Undoubtedly the best form of sunglass available. You will see much better through your car windscreen, and glare from water is reduced.

Multicoating (reflection free) puts a series of very thin metallic layers on the surfaces of a lens to reduce internal reflections. Not only do you see better through the lens, but other people see you better. The latest coatings are much improved, but as with camera lenses, they should be treated with care and not exposed to sudden changes of temperature. Always clean and rinse in luke warm water - never under the tap - to maintain the surfaces in good condition.

Hardening refers to a chemical or heat treatment to improve the breakage characteristics of glass, and is sometimes incorrectly used to refer to the scratch resistant coatings on plastic lenses.

Tinted lenses in many colours are possible for most materials.

Special lenses are available for particular requirements.
Our extensive knowledge of lenses assists matching available lenses to your needs.