Do i need high index lenses? Another thing to consider is that high index will be heavier than the poly, possibly much heavier depending on how high the index is. These are the most common lens materials found in prescription lenses.
Fletcher Opticians
That plus the index change from high index to.
When the refractive index is 1.7 or more, the lens is usually about 50% thinner than it’s glass or.
Polycarbonate lenses were introduced sometime in the 1980s by the gentex corporation. Most people can’t perceive the color distortion at these levels. It takes longer to manufacture these lenses, and because of this, the higher quality is reflected in the price. Polycarbonate lenses rose to critical acclaim due to its durable, and additional properties.
It looks as though the vsp one is physically bigger, and from zooming i can see from the measurements printed inside the temple that it's 2mm larger per eye (54 in the wp vs 56 for the vsp).
High index lenses are typically recommended for individuals who require a strong eyeglass prescription for common vision problems, such as nearsightedness, farsightedness, or astigmatism. However, it’s important to note that this blog post concerns itself primarily with lens thickness rather. There isn’t all bad news, however. High index lenses are more expensive than polycarbonate, but there are no polycarbonate high index lenses.
I have progressives in plastic, high index (1.67) and trivex.
High index plastic tends to have a greater visual clarity and, of course, a thinner profile than polycarbonate which only has a 1.59 index. The latter is simply thinner, and lighter, than the former. This new eyeglass lens material had a high index of refraction, making it to be the lightest and thinnest lens material available then. You wil also find that most high index lenses will be aspheric, my personal preference is for high index.
Polycarbonate lenses also provide you with protection from 100% of the harmful uv rays from the sun.
Polycarbonate lenses if you are looking for thinner, lighter lenses that are comfortable, high index is the way to go. At the same time, there is less need for high index, if you have a very low prescription. Polycarbonate abbe value = 30; Should you worry about abbe value?
1.67 high index lenses can offer the best of both worlds.
Trivex has a low index of 1.53, similar to standard plastic. Sometimes polycarbonate can be thinner than high index lenses because you can ask for a 1.0mm center thickness in a polycarbonate, whereas you have to have a 1.5mm center thickness in other. Lenses with a refraction index of 1.7 or higher are at least. There are a few factors here to consider.
As for the other questions, longevity of the lenses is not a major concern as they are only needed for the next 3 months or so.
As chip mentioned poly has a high amount of chormatic abberation. High index has less visual distortion, probably better cosmetic appearance. The higher that number, the thinner the lens will be even with the strongest types of prescriptions. So if you are looking for cheaper lenses, poly may be a good choice.
The absolute thinness of the lens is obviously one factor, but the clarity of your vision is also important.
High index plastic has similar scratch resistance to trivex. Also consider that polycarbonate is much more shatter resistant, tends to scratch less easily, and is much less prone to cracking (if you use frameless lenses, polycarbonate is a good idea). Crown glass abbe value = 59; Polycarbonate lenses have an index of refraction of 1.59, and will generally be about 20% thinner than standard plastic lenses.
The previous material worn was contact lenses.
And that is the basic difference between 1.67 and 1.74 high index lenses: The general range of refraction is around 1.53 to 1.74. Polycarbonate is used in 35% of all prescription glasses. Affordability was not an issue, there was only a $10 difference between the 1.59 polycarbonate and 1.61 high index.
This is due for a variety of reasons, but essentially, it comes down to the fact that 1.67 high index lenses are made of higher quality.
High index plastic’s index ranges from 1.67 to 1.74, making it considerably thinner and more lightweight than trivex, especially in higher prescriptions. As to thickness it would depend on individual application and design of asphericity. Trivex is more impact resistant than high index plastic, making it a much better choice. The trivex are my favorites, due to optics/general indestructibility.
High index plastic is much more scratch resistant than polycarbonate, so in normal glasses you can expect high index to have a longer life than poly.
