2. PROGRESSIVE LENSES VS. OTHER TYPES OF LENSES:
Alas, the inevitable progressive lenses vs bifocal debate.Fortunately, it can be broken down easily.
1. PROGRESSIVE LENSES VS. BIFOCALS
No lines across the lenses, and cosmetically more appealing: bifocals have a visible line on the lens between the different settings which can cause an image jump when refocusing your eyes from the distance correction to the reading section. They can also only correct two strengths – distance and reading.
HOW DO PROGRESSIVE LENSES DIFFER FROM ORDINARY BIFOCALS?
Bifocal lenses provide a distinct near and far viewing area, but no intermediate area (3-20 feet away). The different viewing areas are separated by noticeable lines that can be awkward, abrupt, and frustrating to the wearer. Progressive lenses have no image jump, featuring a continuous field of vision.
With the rise in computer usage, most people need intermediate correction as well as distance and reading.
Progressive lenses are the only ones that can offer three corrections within one lens. Other benefits include a wider field of vision and an easier adaptation. So, bifocals tend to be more of an alternative or second-best option.
Varifocal lenses, also known as progressive lenses, are used when you have two prescriptions, one for distance and one for reading. Varifocal lenses work by having a gradual change in strength from the top of the lens to the bottom and multiple focal points in between.
The upper part of the lens contains the distance power, the middle of the lens has the intermediate ranges and the lower portion, the reading part.
2. PROGRESSIVE LENSES VS. TRIFOCALS
Almost all progressive lenses are trifocals with no line.
The line is eliminated by a more natural transition and a better optical experience. There is also a lens known as the blended bifocal which is the equivalent of a progressive lens.
What most people need to know is that it corrects distance and near, not intermediate. As for anyone wondering if progressive lenses are the same as varifocals, this is a European term used to describe progressive lenses. They also offer two corrections.
WHAT DO PROGRESSIVE LENSES LOOK LIKE?
To the naked eye, progressive lenses look like most other lenses. Only trained optical technicians and opticians will be able to identify them.But even though they might look like any other lens, some big differences set them far apart.
They are multi focal lenses used to correct distance, near sight and intermediate sight for when you’re using the computer or looking at a screen.
Most progressive lenses will have laser etchings in the lens that are virtually invisible to the wearer and can only be seen using a special “identifier.”
These laser etchings will notify the optician of the added power (which is the strength needed to correct for reading), the starting point of the additional power, and the lens material and the manufacturer of the lens.
WHAT CAN PROGRESSIVE LENSES HELP WITH?
To answer who needs progressive lenses or who should get this type of lenses in one short sentence isn’t possible. They help with so many things and there are also many optical conditions treatable with the incredible engineering of these lenses!
Most people could benefit from a little “boost” in near vision, it can increase dependence on the magnification and most doctors would recommend waiting until presbyopia has begun.
You don’t have to be diagnosed with a condition to take advantage of the technology-infused into progressive lenses. If your vision is blurry when focusing on something, PAL's could be all you need.
It comes down to whether you need sight correction for distance, intermediate or near, and what you do. Let’s see:
NO LINE BIFOCAL SUNGLASSES
Why have several pairs of glasses for different activities – reading, computer use, distance, television watching, etc, when you can have progressive glasses?When the sun is up, you need a good pair of progressive sunglasses to block UV rays and also take care of your vision.
Progressive lenses are often prescribed for people suffering from presbyopia, which usually affects people over 40.
Presbyopia usually occurs at around age 40, when people experience blurred near vision when reading, sewing or working at the computer. You can’t escape presbyopia, even if you’ve never had a vision problem before.
Nearsighted people will notice that their near vision blurs when they wear their usual eyeglasses or contact lenses to correct distance vision.
This is why progressive lenses are ideal for patients who have presbyopia – a vision condition marked by a decrease in the ability to focus sharply on nearby objects. As we age naturally, our ability to see nearby objects and objects in the distance can decrease.
Progressive lenses address separate visual needs in one lens. And it is also why progressive lenses are ideal for patients who have presbyopia.
Rather than a line separating these areas, they are “blended” together within the progressives, often with the middle portion of the lens serving as intermediate vision correction when necessary.
However, as this study reveals, progressive lenses are also used to reduce the progression of myopia.
Progressive lenses can correct astigmatism but are not solely used for astigmatism correction. Astigmatism is when the eye is no longer spherical, but more football-shaped.
That sends light to different parts of the eye instead of at the center. It is fairly common with most glasses-wearers but is not dependent on any other factors (like myopia, hyperopia, or presbyopia).
HOW DO PROGRESSIVE LENSES WORK WITH HIGH PRESCRIPTIONS?
Patients with higher prescriptions can still benefit from progressive lenses. It’s usually not the design that will determine the type of lens that will work for the patient, but the lens material.
The industry standard has mostly moved away from using glass lenses because they are significantly heavier than more modern materials and can make wearing glasses uncomfortable.
CR-39 Plastic works well for low prescriptions and has an optical clarity comparable to glass.
Polycarbonate has become the industry standard for lenses.
It’s thinner, lighter, more scratch-resistant, and shatter-resistant, as opposed to CR-39 and glass. Patients with higher or more complex prescriptions will benefit more from hi-index
(which is available in multiple indexes, 1.67 is what we use, but the highest index is 1.74 and is the thinnest material available).
Hi-index lenses have a higher optical clarity than polycarbonate and are high-tensile, which is great for drill-mounted or rimless frames.
The difference in thickness between 1.67 and 1.74 is marginal, but the price difference is significant. However, the availability of lenses in certain prescriptions may limit which material a patient can get. Someone with a -12.00 may only be able to get a 1.74 in a certain lens type