High-index plastics (1.60, 1.67, 1.74) bend light more strongly so lenses for strong prescriptions can be thinner and lighter. Most high-index monomer comes from Mitsui Chemicals' MR series; lens casting is concentrated in Japan, Korea, Thailand and China.
Varieties (worldwide)
1.60 index lenses1.67 index lenses1.74 index lensesHigh-index aspheric lensesHigh-index progressive lensesHigh-index lenses for rimless framesMR-8 and MR-7 monomer lenses1.90 index glass lenses