Ophthalmic Products and Materials 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 Ophthalmic Products and Materials flashcards as text
Which lens material has the highest Abbe value among commonly used ophthalmic plastics?
Answer: CR-39 (Allyl diglycol carbonate)
CR-39 has an Abbe value of approximately 58, the highest among common ophthalmic plastic materials, indicating the least chromatic aberration.
A patient reports their anti-reflective coated lenses show a persistent colored sheen even after cleaning. This most likely indicates:
Answer: A delaminating or deteriorating AR coating
A persistent or irregular colored sheen after cleaning suggests the AR coating is delaminating or degrading and the lenses should be replaced.
What is the primary purpose of a hard coat applied to plastic ophthalmic lenses?
Answer: Improve scratch resistance
Hard coats are applied to plastic lenses to improve scratch resistance, since most plastics are inherently softer than glass.
Which frame material is most commonly associated with nickel allergy reactions in patients?
Answer: Monel
Monel, a nickel-copper alloy widely used in eyewear frames, is the most common source of nickel contact dermatitis in optical patients.
High-index lenses with an index of 1.74 compared to CR-39 (1.50) will produce lenses that are:
Answer: Thinner but heavier
While high-index 1.74 lenses are significantly thinner, the denser material makes them heavier than CR-39 lenses of equivalent prescription.
A progressive addition lens (PAL) is ordered with a +2.00 add. What is the purpose of the 'corridor' in a PAL?
Answer: To create a gradual transition zone between distance and near powers
The corridor in a PAL is the progressive zone through which power gradually increases from the distance prescription to the full near addition power.
Which lens treatment blocks wavelengths below approximately 380nm to protect against UV radiation?
Answer: UV400 treatment
UV400 treatment blocks all ultraviolet light up to 400nm wavelength, providing comprehensive UV protection for the eye.