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Your Prescription Explained

Your Prescription Explained

When you obtain your Prescription from your optician it will look something like these types below:

Figure 1: A Standard Prescription example

Figure 2: Another Standard Prescription example

Figure 3: A Prescription containing a prismatic correction

SPH (Sphere) This is the value that corrects your vision for long or short sightedness. The values have either a + or – in front or above the value you require. The values for this go up in 0.25 steps ie: 0.25, 0.50, 0.75, 1.00, 1.25 and so on.

CYL (Cylinder) This is the value that corrects the astigmatism in your prescription if you have any. Astigmatism is the irregular curvature of the front of your eye and is very common amongst the world population. The values have either a + or – in front or above the value you require. The values for this go up in 0.25 steps ie: 0.25, 0.50, 0.75, 1.00, 1.25 and so on.

AXIS (Axis) This is the axis that the astigmatic correction needs to be set at. There are no + or – values in this part of the prescription. The values for this go up in 1’ intervals from 0 to 180.

PRISM (Prism) This part of the prescription is for people requiring a wedge shaped piece of plastic or glass in their prescription to make their eyes work together as one or both of their eyes deviate away from their correct optical line. These values go up in 0.50 steps and generally don’t go over 6.

BASE (Base) This is the direction the prism is to be set at in your lenses. The direction will either be UP, DOWN, IN or OUT.

ADD (Addition) or NEAR This is the additional required power for you to be able to read without straining your eyes that is ontop of your distance prescription(If you have one) Most people over 40 require a reading addition.

Other values:

Plano Infinity } Theses values mean there is no required prescription in that field. O or Zero

DS (Diopter Sphere) This can be written in the CYL box meaning you only need a Spherical Correction.

If you require distance spectacles then please do not include the ADD or NEAR value.

If you require reading spectacles then please include the ADD or NEAR value. You may also have an INTER value on your prescription. This is generally used for computer glasses or specialist glasses for reading at a certain distance. Please contact us for advice if you have this value that needs to be made up.

Pupillary Distance (PD)

This measurement is the distance between the centre of your pupils that is measured in millimetres. Opticians do not tend to give out this measurement as it encourages patients to buy their spectacles them. It is usually written as one measurement such as 60 (60mm) but can also be shown as R 29 L 31. When written like this it is the individual distance from you right and left pupils to the centre of your nose. When Varifocals, High Prescriptions or Prisms are ordered the measurement is usually split individually. For most Single Vision prescriptions it is written as one value. If you do not know this measurement and don’t want to measure it yourself then we will make your PD the national average (63) for men and (60) for women.

Measuring your Pupillary Distance (PD):

Asking a friend to help you:

Download our PD Ruler and instructions PDF here to aid with measuring your PD.

This is the easiest method for measuring you PD. With your friend sitting opposite you at the same height ask them to place a ruler across your forehead just above your eyes with the millimetre side facing upwards. Next ask your friend to close their right eye and you then look directly into their left eye. Ask your friend to slide the ruler so that the zero value is in the centre of your right pupil and to keep the ruler very steady across your forehead. Then ask your friend to close their left eye and for you to look directly into their right eye. Your friend will then read off the measurement to the centre of your left pupil. And that’s it! It really is that easy! Please see the diagram below to help you further.

Using your current glasses to measure you PD with help from a friend:

Put your glasses on so that they are comfortable and steady. Ask your friend to stand opposite you and mark on your lenses the position of your pupils with a non permanent marker.

You should now see two lines directly infront of you whilst wearing your spectacles. Take off your glasses and measure the distance between the two markings. And that’s it! If the measurement reads 6cm the PD distance will be 60. If the measurement is 6.3cm then your PD will be 63.

For Varifocal Measurement simply measure from your right eye to the middle of your nose and then from the middle of your nose to your left eye to obtain the required individual readings for your right eye and left eye.

Download our PD Ruler and instructions PDF here to aid with measuring your PD.

Lens Types:

Single Vision:

Single Vision Lenses can be used for either Distance, Computer / Music or Reading vision. The lenses contain the same prescription throughout the lens and they are the most commonly used lenses in the optics Industry. They can be personalised with many different parameters. Please see below for further information.

Bifocals:

Bifocals are used for when people need two prescriptions: one for reading and one for distance. For people wishing not to have two pairs of glasses for these puporses bifocals are used to have both prescriptions in one lens. The top of the lens is used for distance and the bottom of the lens is used for reading. They have a visible line on the lenses as shown below:

Varifocals:

Varifocals are lenses that combine your distance, reading and intermediate prescriptions into one lens. They look exactly like Single Vision lenses and have no visible lines on them. People who use Varifocals have an advantage over people using Bifocals as they have an intermediate distance in them aswell. This is used for computers or for anything that is at arms length away to be seen without having to move closer to the object they are viewing. Varifocal lenses have some slight distortion on the lenses because of the way they are made. This means you have to move your head more when using Varifocals so not to catch some of the distorted areas. There are hundreds of types of Varifocals and they differ by some having more distortion on the lenses than others.

Optional Extras:

Hard Coating or Scratch resistant coating:

This is a hard resin layer applied to you lenses to help resist scratching of your lenses. At specsuperstore.com we supply all our lenses with a FREE scratch resistant coating.

MAR Coating or Anti Reflective Coating:

This coating eliminates glare from car headlights, computer screens, fluorescent lighting and stops noticeable reflections on your lenses. Please see below how Anti-Glare eliminate car headlights:

Without Anti Reflection Coated Lenses

 

With Anti Reflection Coated Lenses

Tints:

Tints are used for filtering bright light from your eyes. They can be purely cosmetic or can be needed for people that are sensitive to light. They are also used for sunglasses.

UV Coating:

UV Coatings filter out harmful rays from the sun that can damage the lens inside your eye.

Transitions or Light Sensitive Lenses:

These lenses have a self adjusting tint that can go from a very pale tint in slightly sunny conditions to going to a very dark tint when it is very sunny. These lenses protect your eyes from harmful UV rays of the sun and are perfect for all the seasons. Please note that these lenses do not work as well inside a car as they do outside due to car windscreens being laminated. Specific sunglasses will work better inside a car.

Polarised Lenses:

Polarised lenses are tinted lenses that cut out horizontal glare produced by the sun. They filter out the unwanted rays and enable viewers to see things a lot crisper in bright sunlight.

 

 

Thin and light lenses or high index lenses:

High index lenses are used to make your lenses lighter and thinner. They are compressed lenses that offer better optical viewing through them. For higher prescriptions they not only reduce the weight by up to 50% but also reduce the thickness by up to 60% making them more attractive cosmetically. High index lenses are usually in the following form: 1.56 index, 1.59 index, 1.61 index, 1.67index and 1.74 index.

The higher the index, the thinner and lighter the lenses.

Safety lenses:

These lenses offer very high impact resistance to moving particles and are used in Safety Spectacles. They are usually in the form of 1.59 index Polycarbonate lenses. The lenses are soft and can significantly reduce the risk of eye damage when using machinery.

Occupational lenses:

These are specific lenses designed for a particular use in spectacles.

Swimming Goggles:

We are able to offer prescription swimming goggles in a variety of colours, sizes and design. The lenses sometimes do not have your exact prescription in but it will be very close for what you need when swimming.

Diving Masks:

We are able to offer diving masks made to your prescription in many different styles, colours and sizes. Some of these goggles can have your exact prescription put in whilst others use standard prescription ranges that will be very close to your prescription.

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