Ophthalmic Lens Materials, Abbe Value, Chromatic Dispersion & Substrate Physics
• 16 min read
CR-39 vs Polycarbonate vs Trivex vs MR-8 vs MR-174: The Definitive Ophthalmic Polymer Engineering Comparison
EXECUTIVE CLINICAL SUMMARY
Selecting the optimal ophthalmic lens material requires balancing refractive index (), chromatic dispersion (Abbe value ), specific gravity (density in ), and mechanical tensile strength. While retailers often blindly push the highest index, optical physics dictates that material selection must be tailored to the patient's prescription magnitude, frame architecture, and visual task demands.
ELLASUV Polymer Optical Metrology Division
Polymer Physics & Optical Dispersion Engineering Group
ISO 8980-3 / ANSI Z80.1 Metrology
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Updated: 2026-09-07
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✓ Peer-Reviewed
The Master Ophthalmic Polymer Engineering Matrix
Below is the empirical material property matrix for all major ophthalmic lens substrates:
| Material | Index () | Abbe () | Density () | Impact (ANSI Z87) | Tensile (kgf) |
|---|---|---|---|---|---|
| CR-39 (ADC Resin) | 1.498 | 58 | 1.32 | Standard | 15 |
| Trivex (Polyurethane) | 1.530 | 45 | 1.11 | High-Velocity | 65 |
| Polycarbonate | 1.586 | 30 | 1.20 | High-Velocity | 35 |
| 1.60 MR-8 (Thiourethane) | 1.600 | 42 | 1.30 | High-Yield | 80 |
| 1.67 MR-7 (Thiourethane) | 1.660 | 32 | 1.36 | Standard | 50 |
| 1.74 MR-174 (Epithio Resin) | 1.740 | 32 | 1.47 | Standard | 30 |
The MR-8 Sweet Spot: Why 1.60 Outperforms Polycarbonate
Developed by Mitsui Chemicals, MR-8 thiourethane resin represents the ophthalmic industry's gold standard for balance. While polycarbonate has a marginally lower index ( vs ), its horrific Abbe value () and poor tensile strength make it prone to cracking in rimless drill-mounts. MR-8 delivers high Abbe (), high heat resistance ( glass transition temp), and an astonishing tensile strength.
Prescription Matching Rules of Thumb
Prescription thresholds for material recommendation:
- Plano to : Standard 1.50 CR-39 or 1.53 Trivex (purest optics).
- : 1.60 MR-8 (ideal balance of thinness and zero color fringing).
- : 1.67 MR-7 (thinner edges with anti-reflective coating).
- : 1.74 Ultra-High Index (maximum cosmetic edge reduction in small acetate frames).
RECOMMENDED CLINICAL OPTIC
Explore BluePro Sharp Focus 1.60 Ultra-Thin
Precision-engineered optical coatings featuring multi-layer dielectric anti-reflection, selective spectral absorption, and ±0.01D prescription tolerances.
FREQUENTLY ASKED CLINICAL QUESTIONS
Expert Answers
Is 1.74 always better than 1.60 high index? ▼
Not necessarily! For prescriptions under -5.00 D, 1.74 is noticeably heavier (density 1.47 vs 1.30) and has lower optical clarity (Abbe 32 vs 42). 1.60 MR-8 gives clearer, crisper peripheral vision with minimal thickness difference.
Why is Trivex recommended over Polycarbonate for rimless glasses? ▼
Trivex has superior tensile strength (65 kgf) and does not crack around drilled screw holes, unlike polycarbonate which is prone to stress fractures. Trivex also provides a crystal-clear Abbe value of 45.
What is MR-8 resin? ▼
MR-8 is a specialized thiourethane polymer patented by Mitsui Chemicals in Japan. It is widely considered the highest quality optical lens material in the world for prescriptions between -2.00 and -6.00 D.
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