Most people (96%, according to one lens supplier) choose plastic (organic CR39) lenses these days as they are half the weight of glass and less likely to break. If the plastic lens breaks it forms smooth edges and does not produce sharp splinters which can enter the eye. Where extra toughness is required polycarbonate lenses are the lens of choice and are suitable for most sports and steam up less than the other materials. According to one large UK optical supplier, single vision lenses account for 68% of all lens types, 17% progressive (varifocal) lenses and 13% bifocals.
Thinner lenses are available now for everyone and are advisable particularly for patients with strong prescriptions. The use of high index materials can reduce the edge or centre thickness of the spectacle lenses and thus improve the cosmetic appearance. It is usually better to have an anti-reflection coat as well as the denser materials tend to reflect light more.
An anti-reflection coat is an almost invisible film applied to the surfaces of spectacle lenses to reduce those annoying reflections from the surfaces. The thickness of each layer of a multilayer anti-reflection coat is 1/1000th the thickness of a human hair. An anti-reflection coating not only improves the appearance of the spectacles as well as enhancing the wearers looks, it actually enables you to see better by eliminating the unwanted reflections which may be particularly noticeable when driving at night. White lenses are those which transmit more than 99% of light. Some high index lenses can look tinted even from the surface reflections. Lenses of refractive index of 1.5 reflect 4% from each lens surface while lenses of refractive index of 1.9 reflect 9% from each lens surface. An anti-reflection coating allows more light through but cuts out reflections when the light source is behind the wearer such as if the sun is behind the wearer.
Progressive lenses used to be called varifocal, varilux, progressive power lenses or progressive addition lenses. Progressive lenses are special lenses which have your distance correction at the top of the lens, the close reading part at the bottom which are linked together seamlessly by the intermediate or arms length distance. As you look down the lens progressively nearer objects come into focus due to the progressive change in lens power. Today there are many progressive lenses available but among the best progressive lenses are the Rodenstock Individualised lenses which started with the Impression ILT (Individual Lens Technology) progressive spectacle lens. Rodenstock Impression® lenses use the prescription and also take into account the anatomical structure of your face and the actual chosen spectacle frame and compute how these two aspects interact with each other in the position of wear, combine to improve vision quality and comfort. In order to achieve this we need to take extra measurements of your face and the frame you have selected. This information is put into the computer and a lens is calculated to provide wider intermediate and near zones, smoother transition from central to peripheral zones allowing faster adaptation. Rodenstock's full range now comprises the following:Impression® Mono (Single Vision), Impression® Mono Sport (Single Vision Sport), Impression Ergo® (Near vision comfort), Impression® (Progressive), Impression FreeSign® (Progressive), Impression® Sport (Progressive Sport), Impression® FashionCurved. Please ask us about any of these designs for a fuller explanation.
D & J Brower Opticians are qualified specialist advisers on the Rodenstock Impression ILT progressive spectacle lens the first progressive lens to be individually designed for you. Rodenstock lenses are of a very high quality and are very popular with many patients. Rodenstock lenses include progressives (varifocals) as well as bifocals and single vision types. Rodenstock lenses are amongst the easiest to get used to and Rodenstock lenses have a guarantee so you can be confident in Rodenstock lenses.
For computer users the Office lens not only corrects vision but allows for correct head and body posture when viewing through the correct zone of the lens. This lens is suitable for all age groups providing the prescription is within the range available. It is untrue that VDU screens emit harmful UV radiation though like anything warm they do give out a bit of IR.
The easiest way to get used to progressive lenses is to switch to the lens which is the easiest to get used to the Rodenstock Impression ILT progressive spectacle lens. If you are having trouble getting used to your new progressive lenses try the following.
The upper part of the lens is used for long distance seeing so simply move your head to face the object you wish to look at and drop your chin slightly if things look blurred.
The middle part of the lens is used for middle distances at around arm's length. Just point your nose at what you want to see and raise your chin slightly to ensure you are looking through the right part of the lens.
The lower part of the lens is used for near vision such as for reading print. Raise your chin and look through the lower part of the lens.
If you find something is out of focus just point your nose at it and move your head up and down slowly until things come into focus.
If after trying all of the above it may be that your prescription is the cause of your difficulty. For example, if there is a big difference betwen the prescriptions for right and left lenses there ay be an image size problem. If you have a one dioptre (1.00DS) difference in power between the two there is approximately a 1% difference in image size, a 2.00DS difference gives a 2% difference and so on and the average brain is said to tolerate up to 4%.
LOW VISION PATIENTS
Low vision patients can benefit from the use of tinted overspecs, which are designed to fit over your own spectacles and provide protection from visible and ultra-violet light. They have wide side-shields and a top ridge to prevent light entry from all angles. There is a very large range available, including clip-on and sunglass styles.
Please click the Overspecs link to view the full range and advise us of your requirements.
SLOW RATE OF SHORT-SIGHTEDNESS
An Australian research team have developed the Myovision™ lens which it is claimed can delay short-sightedness (myopia) progression by 30%. Instead of a child needing 6 dioptres of correction with the Myovision™ lens used for a number of years around ages 7 8 they will require only four dioptres of correction. The lens works by ensuring that peripheral (side) rays of light fall on or in front of the peripheral part of the retina and not behind the retina as is the case with other types of lenses.