Lens Materials: CR-39, Polycarbonate, Trivex, and High-Index — What to Choose?
Comparing CR-39, Polycarbonate, Trivex, and High-Index lenses: pros and cons, who suits which material, and the relationship with refractive index — lens selection advice at the store.
Optometrist Vũ Văn Tiệp
March 28, 2026
Choosing lenses is not just about selecting a brand or price — the base material determines thickness, weight, impact resistance, and partly the optical quality you experience daily. The most common materials on the market are CR-39 (the "standard" optical plastic), polycarbonate, Trivex, and various high-index (1.60, 1.67, 1.74…). This article helps you understand each group, compare based on needs, and avoid choosing incorrectly just because you heard "higher numbers are better". Combine reading more about what lenses are and thin high-index lenses.
CR-39: Traditional "Optical Plastic"
CR-39 (allyl diglycol carbonate) has long been the gold standard for low to medium prescriptions due to its stable optics, affordable price, and ease of processing. Disadvantages: with high myopia, the lens edges can be thick unless you choose edge-covering frames or higher refractive index. CR-39 also falls short compared to polycarbonate/Trivex in impact resistance — not the first choice for active children or contact sports. Suitable for those with light prescriptions, office work, prioritizing natural images, and budget.
Polycarbonate: Safe, Lightweight, Popular for Kids
Polycarbonate is light, impact-resistant, and thinner than CR-39 at the same prescription — hence often recommended for students, safety glasses, and some sports eyewear. The optics may be slightly inferior to CR-39 in some edge designs, but users typically notice little difference at normal prescriptions. A quality coating is needed to reduce reflections as the surface easily interacts with the environment. For a deeper comparison with Trivex, see polycarbonate or Trivex.
Trivex: Safe Group, Many Prefer the Optics
Trivex also belongs to the light, safe group, sometimes described as having "pleasant optics" compared to poly for some sensitive eyes — the price is usually higher than polycarbonate. Suitable when you want to balance between safety and visual quality, or when the optician suggests based on prescription / frame thickness.
High-Index (1.60, 1.67, 1.74…): Thin Edges, High Myopia
High refractive index makes lenses thinner at the same diameter and prescription — important for high myopia or rimless / thin metal frames. However, it is not always “the higher, the better”: 1.74 is more expensive, sometimes has color aberration or curvature that requires adjustment; for moderate myopia, 1.60–1.67 with regular frames is already aesthetically pleasing. Read lenses for high myopia and which brand of lenses to choose.
Quick Selection by Priority
- Safety + Kids + Sports → Polycarbonate or Trivex.
- Budget + Light to Medium → CR-39 or 1.56 depending on the catalog.
- Thin Edges + High Myopia + Visible Frame → suitable high-index (usually 1.60–1.67, depending on prescription).
- Progressive / Multifocal → still need the corridor and lens height correct — see what multifocal lenses are.
Materials and Coatings: A Twin Pair
With CR-39, the quality of AR coating can greatly affect the glare experience. High-index lenses usually should have AR to reduce edge reflections. Don’t compare prices just by “1.67” — you need the line name + coating on the invoice.
Questions to Ask the Optician
"With this prescription and frame, which material provides the thinnest edges within budget X?" and "What coatings are included, and how long is the coating warranty?"
Materials and Lens Shape: Closely Related
With the same refractive index, full round lenses and oval / square lenses can give different thickness perceptions due to effective diameter and center offset. Full rim frames covering edges help CR-39 handle high myopia better; rimless frames expose edges, so they often push towards high-index or reduce diameter (smaller DAO). When you hear “1.67 but still thick”, common reasons are too wide frames or large PD causing the lens to be off-center cut significantly — not due to “poor brand”.
CR-39 vs Poly/Trivex: When Does Work Safety Decide?
In mechanical, construction, contact sports environments, the shatter resistance criterion is more important than absolute clarity. Polycarbonate and Trivex are often categorized as impact-resistant, making them more suitable than CR-39. Conversely, if you experience few impacts, work in an office, and have moderate prescriptions, CR-39 remains a balanced choice regarding price–image. Don’t confuse surface hardness with shatter resistance: some "hard" lenses can still shatter when dropped if the base material is not in the safety group.
High-Index: Read the Catalog Instead of Just the Numbers
1.60, 1.67, 1.74 are refractive index labels; within the same level, the line name (Aspheric, double aspheric, depending on the brand) affects distortion, center thickness, and coating adhesion. An entry-level 1.67 lens can sometimes be thicker than a premium 1.67 lens at the same prescription due to optical design and blank size. Therefore, comparing prices “1.67 A vs 1.67 B” should inquire about the expected thickness on specific frames or check for simulations if the store has them.
Children, Sports, and “All-Day Wear Glasses”
Children often throw glasses, run, and collide on the playground — poly/Trivex are often prioritized. Adults wear glasses for 10–14 hours/day need to consider weight: high-index too thick at the center (farsighted) or too heavy at the edges (high myopia + thin metal frames) can cause slipping frames and nose fatigue. Combine nose pads, proper fit, and frame adjustment advice after fitting — see more about the lens cutting process.
Photochromic, Polarized, and Pressure on Materials
Photochromic or polarized lenses are functional layers on base materials: poly/Trivex/CR/high-index can all be made, but thickness, base color, and color change speed vary. If you need indoor glasses plus outdoor in low light, don’t just choose the material — choose the right color-changing technology and suitable dye color; read photochromic and polarized.
Common Mistakes When Drawing Your Own Conclusions About Materials
- “Light myopia means 1.74 for thinness” — often wasteful, edges are already thin.
- “Poly is bad, so never use it” — with many prescriptions, the perceptual difference is smaller than the safety benefits.
- “CR-39 is outdated” — still the economic standard for simple single vision lenses.
- “Just buy an expensive blank, a careless shop will still look good” — lens center, edges, coating, and frame fitting determine 30–40% of the experience.
Conclusion
CR-39 suits light to moderate prescriptions and budget; polycarbonate / Trivex suits safety; high-index suits high myopia / edge aesthetics. The final decision combines measurements, frames, and lifestyle needs. Continue choosing lenses · contact · articles.
Loading comments...
Leave a comment
Note: Comments are moderated before they appear. Please keep your comment respectful and appropriate.