Lens materials, coatings, and dispensing terminology tested on optician certification exams.
34 cards · basic cards · AI-written, checked twice. Edit anything.
- What is the refractive index of CR-39 plastic?
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1.498- Define a high-index lens.
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A lens material with a refractive index above 1.53, allowing thinner lenses at the same power.- What is the primary advantage of polycarbonate lenses?
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High impact resistance and safety, ideal for sports and children's eyewear.- What material is Trivex?
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A urethane-based plastic lens material with high impact resistance and excellent optics.- What is the main disadvantage of glass lenses?
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Heavy weight and poor impact resistance, creating a safety hazard.- What does an anti-reflective coating do?
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Reduces light reflection from lens surfaces, improving light transmission and reducing glare.- What type of coating protects against ultraviolet light?
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UV-protective coating or UV blocker.- What does a scratch-resistant coating prevent?
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Surface scratches and abrasion damage to the lens.- What is a photochromic lens?
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A lens that darkens in sunlight and clears indoors due to light-activated chemical changes.- Define a progressive lens.
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A multifocal lens with a gradual change in power from distance at the top to near at the bottom, with no visible lines.- What is a bifocal lens?
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A lens with two distinct optical powers, upper for distance and lower for near vision, separated by a visible line.- What is a trifocal lens?
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A lens with three zones of power: distance (top), intermediate (middle), and near (bottom), separated by visible lines.- What is a single-vision lens?
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A lens with uniform power throughout, designed for one focal distance.- What is an aspheric lens?
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A lens with a non-spherical surface shape, reducing spherical aberration and providing thinner profiles.- What is prism in an optical lens?
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The lateral displacement of light rays produced by an unequal change in power across the lens surface.
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