There are many different types of spectacle lenses, each designed to suit a particular vision problem. Features such as anti-reflective coatings and lens tinting can add extra functionality to your lenses to suit your lifestyle. All of our spectacle lenses are manufactured in Australia by CR Surfacing Laboratories, Australia's premium lens laboratory. This allows us to offer patients the benefits of the very latest technology in lens design and manufacture. See the state-of-the-art lens production process at CR Surfacing in this video:
Single vision lenses are the most commonly prescribed type of vision correction in spectacles. These have the same focal power over the whole lens and can be used to correct a variety of vision problems. These come in spherical and aspherical designs, the latter more often used in higher prescriptions to reduce distortions and lens thickness.
Bifocal lenses are prescribed when vision correction is needed for both distance and near/reading. The sections are clearly defined, with the reading portion looking like a half-circle towards the bottom of the lens. There is no correction for intermediate vision. Bifocals are less commonly used with the invention of multifocal lenses.
Trifocal lenses provide three viewing distances: near, intermediate and distance. The three sections are clearly defined on the lens. These are also less common now that modern-day progressive lenses can provide the same range of vision.
Multifocal lenses, also known as progressive lenses, allow you to see near, intermediate and long distances without needing to change spectacles. The top area of the lens is used for distance vision and the bottom area is used for close vision. The area half-way between the top and bottom of the lens is used for intermediate viewing, such as at a computer screen. Multifocal lenses can be more appealing as there is gradual change between viewing the distance and reading parts of the lens. As there is no visible line separating the different areas, these lenses are the most cosmetically appealing. The field of view in a multifocal lens is narrower than in a single vision lens or bifocal, and there is some distortion outside of the central corridor of the lens. Most patients adapt to this very well after a few weeks by learning to move their eyes and head together to keep their gaze through the 'sweet spot' of the lens.
Occupationals solve the problem of a pair of reading glasses not providing clear vision on computers and intermediate objects. Because of this, some optometrists refer to them as 'modern-day reading glasses!' Occuptionals are a variety of multifocal lens designed to give a wider field of view for intermediate and near focuses. These lenses do not provide clear vision for distance but are great for anyone in an office environment, as the top of the lens gives a customised focus for distances further away than your habitual reading point.
The refractive index helps to reduce the volume of the lens material, resulting in a thinner lens. The higher the refractive index, the more dense the plastic. The benefit of this is that we can use the refractive index to improve the comfort and appearance of your glasses.
If you wear a minus lens (for nearsightedness), your lens will be concave in shape - thinner at the middle and thicker at the edges. The edge thickness can be reduced with a higher refractive index. With a plus lens (for farsightedness) the lens shape is convex – thinner at the edges and thicker at the centre. The central thickness will be reduced as the refractive index increases.
Depending on your spectacle script and frame selection, you may want to consider a higher index in order to make your lenses feel more comfortable, more durable and thinner. Ask our friendly staff about the refractive index.
There are a number of different coatings available for your lenses which aim to improve their performance. Such coatings include an anti-reflective (AR) coating (also referred to as a multi-coat), scratch resistance coating and UV coating. Our lens supplier CR Surfacing provides state-of-the-art coatings for your lenses.
Your glasses are constantly exposed to conditions causing wear and tear. A scratch resistant coating helps to improve the durability of the lens, helping your lenses to last longer.
Anti-Reflective (AR) coatings help to prevent glare and reflections. These can be particularly important for higher prescriptions, computer use and night driving. They are cosmetically appealing, allowing people to see your eyes rather than reflections from the lenses. The Satin UV AR coating from CR Surfacing provides superior UV protection, glare reduction, durability, anti-scratch, anti-fog and water-repellent properties.
Hardcoats are designed to provide optimum scratch-resistance properties. Because of the way the Satin AR Coating reduces reflections, any grease or oils from your skin may show up more easily on the lens surface. Hardcoats do not show up these marks as easily and thus are easier to keep clean, making them ideal for outdoor, messsy or dusty work. The Synergy hydrophobic hardcoat from CR Surfacing is a premium quality hardcoat with anti-scratch, anti-fog and water-repellent properties.
It is important to consider UV protection if wearing your spectacles outdoors or even while driving to protect you from the sun's harmful rays.
All types of lens, including multifocals, can be permanently tinted toprovide glare protection when in the sun.
Driving and watersports especially can be improved with the use of polarised sunglass lenses - these eliminates unwanted reflections from road surfaces and water.
To give more functionality to your normal spectacles you can choose to have them made with a transitions lens. Transitions are activated by UV light, darkening when outside and lightening to a completely clear lens inside. This process often takes less than a minute, making them suitable for full-time wear without having to worry about carrying an extra pair of sunglasses.