Trivia 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 Trivia flashcards as text
What are the two contemporary formats for writing prescriptions?
Answer: Plus-cylinder and minus-cylinder
Ophthalmic prescriptions for astigmatism can be written in two primary formats: plus-cylinder and minus-cylinder. These formats represent the same optical correction but use different conventions for specifying the cylinder power and axis. Minus-cylinder is more commonly used by optometrists and ophthalmologists, while plus-cylinder is sometimes used in manufacturing or older prescriptions, but both are valid and convertible.
What is the term of the measurement of a lens's optical clarity?
Answer: Abbe value
The Abbe value is a crucial measure of a lens material's optical clarity, specifically its chromatic aberration or ability to disperse light. A higher Abbe value indicates less dispersion, meaning colors are less likely to separate into fringes, resulting in sharper and more color-true vision. This value is essential for assessing the quality of a lens material.
The ________ lens at the 90th meridian always reads vertical imbalance error.
Answer: weaker
When checking for vertical imbalance error at the 90th meridian (which represents the vertical axis), the weaker lens is the one that will reveal the error. This is because the lens with less power in the vertical meridian has a reduced ability to compensate for any vertical deviation, making any existing imbalance more noticeable and problematic for the wearer.
Which two types of frame materials are available?
Answer: Metal and plastic
Eyeglass frames are broadly categorized into two main types based on their material: metal and plastic. Within these categories, there are numerous sub-types, such as titanium, stainless steel, acetate, and nylon, each offering distinct properties in terms of weight, flexibility, durability, and aesthetic appeal. These two classifications encompass the vast majority of frame constructions available.
What frame adjustment lowers the frame's front?
Answer: Spreading pads further apart
Spreading the nose pads further apart on a frame causes the frame front to sit lower on the wearer's face. This adjustment effectively increases the distance between the pads, allowing the frame to slide down the bridge of the nose. Conversely, bringing the pads closer together would raise the frame front.
What aspect of a lens makes astigmatism correction?
Answer: Cylinder power
Astigmatism is corrected by the cylinder power in a lens, which has different refractive powers along different meridians. This cylindrical component compensates for the irregular curvature of the cornea or lens in an astigmatic eye, ensuring light rays focus correctly onto the retina. Without cylinder power, astigmatism would remain uncorrected, leading to blurred or distorted vision.
What substance has the best optical qualities?
Answer: Crown glass
Crown glass is traditionally considered to have the best optical qualities among common lens materials, primarily due to its high Abbe value (low chromatic aberration) and excellent clarity. While heavier and more prone to breakage than plastic alternatives, its superior optical performance makes it a benchmark for visual acuity and color fidelity. Modern materials offer alternatives, but crown glass remains a gold standard for pure optical quality.