The Simple Guide to Confusing Lenses ….
Visiting your optician can sometimes feel a little confusing, especially if you are new to glasses or your vision has changed. The subject of Prescription lenses and what they even are is a broad one, so in order to make it easier we have explained each one in a little more detail. It’s our simple guide to confusing lenses!
In our opinion, lenses in your spectacles should do two things. Firstly, they should allow you to see clearly (the goal of clear sight is always important) and secondly, they should protect your eyes, providing comfort in each of the conditions that you use them.
Most patients (predominantly under 40 years of age) will only require Single Vision Lenses. A single vision lens is a lens which has the same power from top to bottom. Lenses are made in a variety of plastic materials, glass can be used, however in 90% of cases the advantages lie with plastic.
Terms used to describe these plastic materials are 1: Index. 2: Aspheric. 3: Surfaced.
This term relates to the density of plastic used. The higher the index, the thinner and lighter the lens will be, indexes used are 1.5, 1.56, 1.6, 1.67 and 1.74
This means that special curves are worked onto the surface of the lens to make the lens flatter and thinner, normally for long-sighters or plus prescriptions: therefore the 1.74 aspheric would be the thinnest, flattest plastic lens that you could get
This is where a standard lens is used, again a specially worked surface to keep the lens as thin looking as possible. They are generally less expensive than aspheric lenses and can be a good option for young children where small frames are used.
Over 40 years of age we tend to see that the lens inside our eyes can stiffen, meaning that a different strength of lens is required for distance and near vision. These lenses come in three main forms 1: Bi-focal 2: Tri-focal 3: Multifocal.
Bi-focal lenses are made up of two parts. The upper part is for distance and the lower part is for reading. There is a line separating these two parts. The width of the reading area can be varied to suit the task undertaken
The most popular form of lens as it covers all distances from near to far. The lens gradually becomes stronger the further down the lens you look through. The lenses are acting like your own lens inside the eye which bends to become stronger the closer objects are. These lenses can be of different index and aspheric just like single vision lenses.
Multifocal lenses come in many different variations, ranging from standard off the shelf to 100% bespoke. the better the lens, the easier they are to use.
The more the lenses are individually tailored to your needs, the more specific the lens becomes. Our experienced team of eye-health experts (Sandie, Kim and Ross) will be able to talk you through these choices and recommend what is best for you.
Not only should your vision be made better, your lens can also protect your eyes. Different coatings can be used on the surface of the lens to reduce glare, reflections and UV.
Coatings, Worth a Look
The following coatings are offered to our patients, as protection for their new lenses and their eyes:
1: AR Coating, Anti Reflection coatings allow more light to pass through the lenses giving better vision & appearance.
2: Hard Coating. Helping to protect against scratches and scrapes.
3: UV Block. Used to stop all UV light, this type causes ageing of the eye.
4: Multi Coat. This combines all of the above and come with a 2 year guarantee.
Questions or Concerns
We cannot stress enough the importance of your eye-health and are more than happy to book your free eyesight-MOT. Or for just £30 you will receive complete peace of mind including OCT and will be looked after by Sandie, Kim or Ross; who between them have over 30 years’ with all eye-health issues.
Colin Simpson B.Sc FBCO
Father of 3, Retired Optometrist, Grandpa, Blogger.