Ophthalmic Lens Materials - Optometry Topic

Ophthalmic Lens Materials Ophthalmic lens materials are chosen based on their optical properties, impact resistance, weight, durability, and cost. Understanding the different lens materials is essential for optometry and ophthalmology exams. 1. Types of Ophthalmic Lens Materials Ophthalmic lenses are primarily made from the following materials: A. Glass (Crown Glass) Composition: Silica (SiO₂), Sodium oxide (Na₂O), Calcium oxide (CaO) Refractive Index: 1.523 (standard), can go up to 1.9 for high-index glass Advantages: Superior optical quality with minimal aberrations Highly scratch-resistant Disadvantages: Heavy Brittle and can shatter easily Poor impact resistance, requiring tempering for safety B. Plastic (CR-39) Composition: Allyl Diglycol Carbonate (ADC) Refractive Index: 1.498 Advantages: Lightweight (about half the weight of glass) Good optical clarity Impact-resistant Easy to tint Disadvantages: Less scratch-resistant than glass (requires coating) Thicker compared to high-index materials C. Polycarbon…