Lens Coatings and Treatments Flashcards
7 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Lens Coatings and Treatments flashcards as text
A patient reports that their anti-reflective coated lenses look smudged almost immediately after cleaning. What is the most likely cause?
Answer: The patient is using a silicone-based cleaner incompatible with AR coating
Silicone-based or alcohol-based cleaners can break down the hydrophobic top coat on AR lenses, making them attract oils and smear more easily.
Which property of a photochromic lens determines how dark it becomes in sunlight?
Answer: The concentration and type of photochromic molecules embedded in the lens
The darkening depth of photochromic lenses depends on the density and chemical nature of the silver halide or organic photochromic molecules within the lens.
A scratch-resistant coating is best described as:
Answer: A hard surface treatment that reduces but does not eliminate lens scratching
Scratch-resistant coatings increase surface hardness to reduce scratching but cannot make a lens completely impervious to abrasion.
What is the primary purpose of a hydrophobic (water-repellent) top coat applied over an AR coating?
Answer: To make the lens surface easier to clean by causing water to bead and roll off
Hydrophobic top coats reduce the surface energy of the lens so water beads up and rolls off rather than spreading, keeping the lens cleaner.
When dispensing AR-coated lenses to a patient who works in a kitchen, which additional coating property is most important to recommend?
Answer: Oleophobic (oil-repellent) properties
Kitchen workers are frequently exposed to cooking oils and grease, making an oleophobic coating critical to maintaining lens cleanliness.
A patient's photochromic lenses do not darken adequately when driving. What is the most likely explanation?
Answer: Automotive windshields block most UV light, which is required to activate photochromic lenses
Standard automotive windshields are laminated with UV-blocking interlayers, preventing the UV light needed to trigger photochromic darkening from reaching the lenses.
Which statement about mirror coatings on sunglass lenses is TRUE?
Answer: Mirror coatings are thin metallic films vacuum-deposited on the front lens surface
Mirror coatings are applied via vacuum deposition (sputtering) as a thin metallic or dielectric film on the front surface of the lens to reflect light away.