Ok, so this is going to be obvious for some of you, but I know there are plenty of people out there that need to know this – I get asked every day!
Know what you’re buying class #1 is in session, it’s time to get the basics right.
What type of lenses am I wearing?
Single Vision: Exactly as it states, these lenses have one prescription across the entire lens. There are no distortions, visible sections or marks on the lens. Singe Vision lenses are most commonly made up as reading glasses (near), Distance, or intermediate (computer distance), however your Optometrist can make them up for you at basically any specific distance you need – just make sure you mention it to them at the time of your eye exam.
Bifocal: Bifocal lenses have 2 distinct sections in them, traditionally Distance and Near. Bifocals can also be used as Near and Intermediate, or Distance and Intermediate. With Bifocals there is a visible section at the bottom called the ‘Seg’ (Segment). This section is clear, but visible due to a different thickness of lens on the bottom half, closer to the nasal side of the lens. The most common design of Bifocal is a ‘D-Seg’, because the Seg looks like a letter ‘D’ on its side. This Seg is available in different sizes, and you can also (with some prescriptions) get an ‘Executive Bifocal’ where the segment goes right the way across the lens. These lenses are now not being used as often as in the past, as all of the technology advancements have moved forward in multifocals lens designs instead. Basically, Bifocals are old technology, and while still useful, we rarely see new glasses wearers opting for them.
Vocational lenses: Vocational lenses are the step between a single vision and a full multifocal (See below). They look like a single vision lens with no visible sections, but act more like a bifocal in that they offer 2 different sections. Unlike a bifocal, vocational lenses have a soft and smooth graduation between the sections, which is hardly noticeable. These are widely used for students and office workers, so that they can view near objects such as books or paperwork and still see computer screens (most commonly set at an intermediate distance) with one lens.
Multifocal lenses (also knows as Progressive lenses): Multifocal lenses have three sections – Near, Intermediate and Distance. They do have some distortions out in the peripheral sections on both sides of the lens, however large advancements have been made over the last few years to eliminate this and it is much better than it ever used to be. The lenses physically look like a single vision lens, with no noticeable sections to be seen. The pro’s of this type of lens is once you find the right design, you should be able to put them on in the morning and do anything in them. The down side, is if you get motion sickness, or have someone dispense them incorrectly (happens WAY too often unfortunately) you may have issues adapting. But don’t let that dissuade you from trying them; there are non-adaption warranties with every lens manufacturer I have ever dealt with but of course, you will need to discuss this with your Optometrist before purchasing. Don’t give up, they’re worth adjusting to but also don’t keep quiet if you’re finding it difficult. There are plenty of options out there and your Optometrist can’t help if they don’t know there’s a problem.
So, that is a VERY basic run down of the main types of prescription lenses. On top of the above, each of these lens types come in different materials, with many coating options and most can be designed using many measurements of where your eye sits in the frame you have chosen and takes your unique prescription into account as well.
As mentioned earlier, this is your Know what you’re buying class #1, there will be plenty more with more info on everything, but please don’t hesitate to ask any questions below!