When you first look at your optical prescription it can be confusing. What do all of the components mean? How do you know whether you need single vision, bifocal or progressive lenses? Lens coatings – do you need them or not?
These are a few of the questions that we are commonly asked and we will try to answer each of them and a few more in this blog article.
When you are ordering prescription safety glasses firstly you need a current prescription, preferably less than a year old. This means that the date on the prescription should be less than a year from today’s date. If in doubt it is best to get a new prescription completed by visiting your friendly local Optometrist.
Once you have the all-important optical prescription you need to be able to transpose the information contained on the prescription into our order form. Most prescriptions look like this:
Right +2.00 / -0.50 x 180
Left +1.00 / -1.00 x 180 ADD +1.50
Optometrists’ Name and provider number
Occasionally they may recommend a lens type like bifocal or multifocal/progressive lens. If the Optometrist has done this it is easier for you to make the lens type selection as you could choose to follow their directions.
Understanding your prescription:
Referring to the prescription above the Right lens has a Sphere component of +2.00 and a Cylinder component of -0.50 with an Axis of 180. The Left eye prescription is made up of Sphere +1.00 with a Cylinder component of -1.00 and an axis of 180.
This prescription has an ADD which tells me that John Smith needs a bit more assistance with reading, so the Optometrist has added magnification on to the prescription, so that his distance and near prescriptions are different.
When a person has an ADD on their prescription, they generally require either bifocal or progressive lenses in their glasses, as they would not be able to walk around or see in the distance with reading glasses.
People that do not have an ADD on their prescription have the easiest time only having the option of Single Vision Lenses. People that do not have ADD in their prescription do NOT need progressive or bifocal lenses.
Now if you happen to have an ADD in your prescription then you will probably need to have either bifocal or progressive lenses. Now, this is an easy decision if you happen to have had either of these lens types before – as you can just choose the same lens type. Now if you haven’t had a bifocal or progressive lens previously then this decision is a bit more difficult.
For those of you that have been getting by with your reading glasses and wearing over-specs or just your general glasses, this information is for you. If you need to keep your safety glasses on for work and you have to move around then reading glasses are not suitable, as you cannot see clearly in the distance.
Bifocal lenses are easily recognizable as they have a line in the lens to delineate the reading area from the distance portion of the lens. These lenses are great for people who need peripheral vision in their safety glasses. As the whole top portion of the lens has the distance prescription contained.
It should be noted that there is no area in a Bifocal lens to make an arms length clear. They only have the 2 prescriptions available in the lens. Distance and near.
Progressive lenses are handy for people who need every distance from the horizon to reading distance clear in one lens. These lenses rely on corridors of clear vision and the distance prescription is in front of your eyes normally and the prescription changes as your eyes move down the lens to the bottom of the frame. The reading prescription is near the bottom of the frame.
You do not get the peripheral vision in a progressive lens. You need to turn your head to point your nose in the direction that you wish to see. Stairs and ladders need practice and holding on to the rail until you are used to this type of lens.
The progressive/multifocal/varifocal lenses all come with a 3 month adaption warranty. If you cannot get used to your new progressive lenses then the manufacturer will change them to bifocal or single vision under warranty.
Now that you have the lens type sorted, you may want to consider lens coatings and extras like transition/photo-chromatic lens types.
Most people that have had glasses for awhile will have come across a multi-coat or anti-reflective coating. This coating does just that it reflects the light away from the lenses, making the lenses clearer to look out of and actually lets 6% more useful light through the lens. This is important for people that want to have Transition or photochromatic lenses, as it means that the lenses change colour quicker.
This coating is also helpful for people that drive at night as it reflects the oncoming headlights away. The coating is also helpful for people that use computers and have overhead lighting as it reflects the glare from these lights away.
Anti-Fog coatings do just what is stated help reduce the chances of the lenses fogging up.
Mirror coatings are available on most Eyres products and they can look spectacular. They are available in gold, silver and blue mirror lens coatings.
These are great sunglass lenses, as boaties and fisherman have known for years. They really cut down the glare reflected off the water, snow, sand, concrete or bitumen. These lenses are tinted all the time.
Transition or Photochromatic Lenses:
Everyone probably knows how these lenses work – you expose the lens to sunlight and the lens goes dark. You go inside or take the sunlight away and the lenses go back to clear. Transition is the most well-known brand of this type of lens and it is available for all of the different lens types and frame styles.