|MARTERIAL REFRACTIVE INDEX=1.499 TOOLING INDEX=1.530|
Bifocals in General
1. The wearers can see the near things by the round shape and see the distance things by the rest of the lenses.
2. The wearers don't need change two different visions glasses when they both reading book and watching TV.
3. The wearers can keep the same posture when they look both the near thing or far thing.