What Exactly Are High-Index Lenses?
High-index lenses bend light more efficiently than standard lenses, so they need less material to correct the same prescription. The result? Noticeably thinner, lighter eyeglass lenses.
Think of it like thread count in sheets — a higher number means finer, more refined material doing the same job. The 'index' refers to the lens's refractive index, or how effectively it redirects light. Here's how the scale breaks down:
- Standard (1.50): The baseline. Works well for mild prescriptions.
- Mid-index (1.56–1.61): A slight step up in thinness.
- High-index (1.67): Where the real difference kicks in for moderate-to-strong prescriptions.
- Ultra-high-index (1.74+): The thinnest option available, ideal for very strong prescriptions.
Most optometrists recommend considering high-index prescription lenses once your prescription reaches +/- 2.00 diopters or above. (Diopters are simply the unit used to measure your prescription strength — a +/- 2.00 is considered moderate, and anything beyond that is where lens thickness really starts to show.) Below that threshold, standard lenses handle things just fine.
How Much Thinner Are High-Index Lenses, Really?
Great question — and the answer is more dramatic than you might expect. At a -6.00 prescription, a 1.74 high-index lens can be up to 30% thinner than a standard 1.50 lens. That's a visible, tangible difference you'll notice every time you put your glasses on.
Beyond thinness, there's weight. Thinner lenses mean lighter frames on your face, which matters when you're wearing them eight, ten, twelve hours a day. And here's a style bonus: high-index lenses eliminate those thick, visible edge rings that stronger prescriptions create with standard lenses — what some people call the 'coke-bottle' look.
That matters if you love fashion-forward frames. Oversized glasses, thin metal frames, cat-eye frames, even rimless designs all look sharper with thin prescription lenses that don't add bulk. When your lenses work with your frames instead of against them — say, in acetate frames or sleek metal styles — you get the full style impact of designs like BonLook's 100+ Montreal-designed collection.
High-Index vs. Polycarbonate vs. Trivex — Which One's Right for You?
This is one of the most common (and least answered!) questions we hear. Each material has a sweet spot, and finding your perfect frame size matters just as much as the lens you choose:
| Feature | High-Index (1.67/1.74) | Polycarbonate | Trivex |
|---|---|---|---|
| Best for | Strong prescriptions | Impact resistance, kids, active lifestyles | Optical clarity, lightweight comfort |
| Thinness | Thinnest option | Moderate | Moderate |
| Abbe value | ~32–33 | ~30 | ~43–45 |
| Weight | Light | Light | Lightest |
What's Abbe value? It measures optical clarity — specifically, how much color fringing (chromatic aberration) you see at the edges of your vision. Higher is better. Trivex leads here, while polycarbonate sits at the bottom. High-index 1.67 lenses land just above polycarbonate, and for most wearers, the difference is negligible with a properly fitted frame.
One important note: high-index lenses naturally reflect more light than standard materials, so an anti-reflective coating is essential. BonLook includes premium anti-glare coating on every pair, so you're covered from the start.
Your best pick depends on three things: your prescription strength, your lifestyle, and the frame style you love. For moderate-to-strong prescriptions paired with fashion-forward frames, high-index is almost always the right call.
Do High-Index Lenses Have Any Downsides?
We believe in honest answers, so yes — there are a few trade-offs to know about:
Cost. High-index lenses cost more than standard options. But the gap might be smaller than you think. BonLook's Very Thin (1.67) lenses start at $269 — that's only a $30 upgrade over the standard lens tier, with scratch-resistant coating, premium anti-glare, and 100% UV protection all included.
Glare. Because high-index materials reflect more light, AR coating goes from 'nice to have' to 'must have. The good news? Any quality provider includes it. (BonLook does, on every pair.)
Optical clarity. The slightly lower Abbe value means you may notice minor color fringing at the very edges of your lenses. In practice, with a well-fitted frame and proper centration, most people never notice it.
Not always necessary. If your prescription falls below +/- 2.00, standard lenses are perfectly fine — no need to spend extra when your current lenses are already thin and comfortable.
How Much Do High-Index Lenses Cost?
Pricing for high-index lenses varies wildly depending on where you shop. Here's what you can expect:
- Online retailers (1.74): $80–$150 for the lenses alone
- Local opticians (1.74): $350–$600, sometimes more depending on coatings
- BonLook Very Thin (1.67): Starting at $269, with scratch-resistant coating, premium anti-glare, and 100% UV protection already included — only a $30 lens upgrade from standard
What affects your final price? The lens index level, which coatings you add (blue light filtering runs +$50 at BonLook; polarizing filters +$80 with Rx), prescription complexity, and frame type. See the full breakdown on BonLook's lenses and pricing page.
Worth noting: many vision insurance plans and FSA/HSA accounts cover high-index lenses as a medically necessary upgrade. Check with your provider — you might be pleasantly surprised.
Ready to See the Difference?
If your prescription is +/- 2.00 or stronger, high-index lenses can transform both the look and comfort of your glasses. Explore BonLook's frame collection with Very Thin lens options, try them on virtually with our try-on tool, or find a glasses store near you for personalized guidance from our team. Your perfect pair is closer than you think.
