Type of ophthalmic lens and its properties
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Ophthalmic lens material
An Ideal Lens Should Have Following Properties-
1. High Degree of Transparency
2. Good Impact Resistance
3. Low Weight
4. Easy to manufacture
5. Inexpensive
Types of lens material
1️⃣ Glass Material
2️⃣ Plastic Lenses
Type of Glass lenses
1️⃣ Crown Glass lenses
2️⃣ Flint Glass lenses
Plastic Lenses : Here are the common types of plastic lenses:
Types of Plastic Lenses
1. CR-39
2. Polycarbonate
3. High-Index
4. Trivex
5. Acrylic (PMMA)
1. CR-39 (Allyl Diglycol Carbonate):
- Lightweight
- Impact-resistant
- Affordable
- Refractive index: 1.49
2. Polycarbonate (PC):
- High-impact resistance
- Lightweight
- Thinner than CR-39
- Refractive index: 1.59
- Suitable for children's lenses
3. High-Index Plastic (HI):
- Thinner and lighter than CR-39 and PC
- Higher refractive index (1.60-1.74)
- Suitable for high-power prescriptions
4. Trivex (Polyurethane-based):
- High-impact resistance
- Thinner and lighter than PC
- Refractive index: 1.53
- Suitable for rimless frames
5. Acrylic (PMMA):
- Lightweight
- Impact-resistant
- Lower refractive index (1.49)
- Less expensive than CR-39