Eyeglass Lens Materials: KOC vs. MR Series – How to Choose?

When selecting lenses for eyeglasses, the base material—optical resin—plays a decisive role in the wearing experience, alongside design and functionality. Among the mainstream high-performance materials, KOC and the MR series are two key options.

Their core difference lies in the balance between refractive index, Abbe number, and toughness.

1. KOC Material (Korea Kuraray)

KOC refers specifically to a polyurethane-based optical resin produced by Kuraray of Korea. Its standout feature is high toughness.

Key Advantage: Superior Impact Resistance. Known as a "bulletproof material," lenses made from KOC are highly resistant to drops, scratches, and breakage, offering exceptional safety.

Main Drawback: To achieve high toughness, its Abbe number is relatively low (typically between 33–36). The Abbe number measures the lens’s dispersion coefficient; a lower value means a higher likelihood of chromatic aberration (rainbow-colored edges), especially in high-Prescription Lenses, which may affect visual clarity and comfort.

Best For: Ideal for sports glasses, children’s eyewear, safety glasses, or any application where extreme durability and safety are priorities. For low-prescription wearers, chromatic aberration is less noticeable.

2. MR Series Materials (Mitsui Chemicals)

The MR series is a range of thiourethane-based optical resins developed by Japan’s Mitsui Chemicals , with several subtypes (e.g., MR-8, MR-7, MR-174). It is the mainstream choice for mid- to high-end lenses today.

Key Advantage: Excellent Optical Balance. MR materials successfully combine high refractive index with a high Abbe number. For example, MR-8 (refractive index 1.60) has an Abbe number as high as 41, meaning it provides thinner lenses while minimizing chromatic aberration for clearer, more realistic vision.

Properties: Offers good surface hardness (scratch resistance), moderate toughness, and excellent UV absorption.

Best For: Considered the gold standard for daily-wear glasses. Particularly suitable for moderate to high myopia / hyperopia patients who want thinner, more aesthetically pleasing lenses without compromising optical quality. MR-7 (1.67) and MR-174 (1.74) provide even thinner solutions for high-prescription users.

3.Summary of Core Differences

4.How to Choose?

If durability and safety  are priorities, especially for active use or children’s glasses → choose  KOC.

If visual clarity, comfort, and thinness are priorities for all-day, everyday wear → choose the MR series (especially MR-8).

Ultimately, consulting with a professional optician—considering your prescription, frame size, habits, and budget—will help you select the most suitable lens material.