1.67 vs 1.74 High Index Lenses
When you order prescription eyeglasses or sunglasses online, you’ll typically be presented with the opportunity to get high index lenses. Two of the most common options for these are 1.67 and 1.74. What are high index lenses and what is the difference between these choices? Should you get them at all? Here are answers to these and other lens questions:
What Are High Index Lenses?
High index lenses are eyeglass and sunglass lenses that has an improved ability to bend light. This ability is technically referred to as the lenses’ “index,” hence the name of this class of lenses.
Why You Should Care
High index lenses offer a couple of big benefits: They’re thinner, lighter, and reduce the change in how your eyes look to others.
Thinner lenses are very beneficial to those who have strong prescriptions. With standard lenses, these prescriptions result in a thick “Coke bottle” look that is unsightly and gives the impression that the wearer is elderly. Such lenses are also heavy, so the glasses quickly become uncomfortable. High index lenses allow even strong prescriptions to be made with thin, lightweight lenses.
Standard lenses have another drawback: They change how your eyes look. Glasses that magnify what you see also make your eyes look bigger to others, while those that shrink what you see will make your eyes seem smaller to onlookers. The strength of the effect depends on the strength of your prescription and the type of lenses you use.
What are the Differences Between 1.67 and 1.74 High Index Lenses?
Lenses that are 1.74 are thinner – and more expensive – than those that are 1.67. However, this doesn’t mean that the thinnest ones are automatically better for you. It turns out that your prescription strength determines whether or not you will notice the difference between the two, and in fact, whether it’ll be worth it to get high index lenses at all.
- Very low prescriptions, such as less than 2 diopters either way, work fine with standard plastic lenses, also known as mid-index lenses. These lenses are often rated at 1.57 or less.
- People with prescriptions in the area of 5 diopters will see a benefit in upgrading to a 1.67 high index lens. At this prescription strength, standard lenses can include fatigue-inducing visual distortion as well as being thick and heavy.
- At 8 diopters and above, it’s worth it to go for the 1.74 high index option.
There are a few other key differences between the strengths of high index lenses. One is the cost: 1.74 lenses can be significantly more expensive than their 1.67 brethren. Perhaps because of this, and the corresponding higher demand for 1.67s, there are more options available for the 1.67s. There are often more colors available for sunglasses tints, and the popular Transitions brand of color-changing lens is only available in the 1.67 form.
Despite this, those with very high prescriptions will find 1.74s to be the better bet. They’re best at preventing distortion of the appearance of the eyes and are lighter in weight.
Are There Other High Index Options?
Yes, but these come with drawbacks that the popular options eliminate. One of the biggest ones is material: Extra-high index lenses, such as those at 1.9, are typically made of glass. While actual glass is excellent for visual clarity, it is also quite heavy even when thin. It is also very easy to break, and in high index form, this can quickly become a highly expensive trait.
What Are Popular High Index Lenses Made From?
They are typically made of polycarbonate, which is a form of plastic that can withstand high impacts. Other forms of plastics are sometimes available, as well.
Should You Get High Index Lenses if Your Prescription is Low?
There is no real benefit to getting this type of lenses if you have a low prescription. In fact, you may see more clearly if you do not. However, there is one circumstance that can force you to do so despite this. That is if you want Transitions lenses.
Transitions lenses change from clear to tinted and back depending on exposure to UV light. This means that when you’re inside, they’re clear, but after you wear them in the sunlight for a couple of minutes, they turn dark. This capability is very enticing to those who don’t want to have to keep switching between regular prescription eyeglasses and sunglasses. The catch? They’re only available as 1.67 high index lenses. In this case, go ahead and get them even if you could actually use standard lenses. It won’t hurt your eyes to have high index lenses when you don’t “need” them for the usual reasons.
What Add-Ons Exist for High Index Lenses?
At most online eyeglass sites, all of the standard options are available. These include anti-reflective coatings, tints, mirroring, anti-scratch coatings, polarization, and possibly more. Ordering them is as easy as checking off which ones you want on the online order form.
Where Should I Get High Index Lenses?
To the dismay of those who run physical optical shops, the fact is that it’s best to buy your glasses online. You have a wider selection of frames, and the frames are often far less expensive than those from an eye doctor’s store. When prices seem equal, which you may see when you compare a discounter’s least-expensive options with online offerings, you’ll find that the online versions have better quality.
Glasses that you buy online are often produced better, as well. Many people complain about having to go back to an optical shop for several “remakes,” while complaints of this sort are low when talking about online sources.
Finally, online stores are less likely to gouge you when you get add-ons. A coating that even a big-box discounter charges $20 for can sometimes be gotten for $5 at an online shop. Basic upgrades like anti-reflective coating and scratch protection tend to show the biggest price differences.
Do I Need a Prescription to get High Index Lenses?
If you want custom prescription glasses, you always need a prescription. That said, it is technically possible to get prescription-free high-index lenses, which you may decide to do if you want Transitions lenses without any vision correction included. Despite this, if you don’t need a prescription, you’re better off just getting sunglasses with standard, non-Transitions, lenses.
Do High Index Lenses Change my Prescription?
No, the prescription itself remains the same no matter what type of lenses you use. The thickness, weight, and visual appeal of your glasses are all that change.
Where Can I Get a New Prescription for Eyeglasses?
Unfortunately, there is no way to check the health of your eyes online. Therefore, we must recommend that you get a comprehensive eye exam at the physical office of an optometrist or ophthalmologist. There is a service for testing your visual acuity online, but it does not test for eye health. If you have a strong prescription, it’s a good idea to make sure that nothing serious is going on.
Do I Have to Get Glasses from My Eye Doctor if I Let Him Examine My Eyes?
No, you do not. Doctors generally aren’t eager to advertise this fact, but by law, they must give you your prescription even if you don’t buy their glasses. Online stores sell tens of thousands of pairs of prescription glasses every year, so it is no longer rare for people to just get prescriptions from their doctors and buy their spectacles elsewhere.
What About my PD (Pupillary Distance)?
This is where some optical shops try to get you. They don’t have to tell you your PD after you see their doctor, and may not give it up unless you buy a pair of glasses. This is legal – and it can also be worked around. Our site offers tips for measuring your own PD, so you don’t need a professional to do it. Alternatively, you can get the cheapest offline glasses option just to get the PD from the optician, and then buy online for every other pair you ever get. Of course, if you do it yourself, you don’t have to buy even one pair of overpriced glasses.
Ordering High Index Lenses Online
Online optical shops like Rx-safety make it easy to order new, high index, prescription glasses online. All you need to do is fill out some forms on the site to get your order started. These forms will collect the needed information on your prescription, desired add-ons, frame style choice, and other necessary details. Then, just enter your address and payment information. Within a couple of weeks or so, you’ll have your new pair of glasses – at a fraction of the cost that you’d pay at a physical store.
To learn more about high index lenses and all of their possible applications, just check out the rest of our site or contact us. We’ll be glad to tell you all you want to know about these excellent options for your vision correction needs.
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