Chapter 12: Fundamentals of Practical Opticianry Flashcards
Opticianry
Specialized area of eye care that includes the making of corrective lenses from refractive prescriptions and the fitting of both the lenses and the eyeglass frames for proper visual correction
Types of Corrective Lenses
1) Single-vision Lenses- typically only correct for a single distance point (either distance or reading)
2) Multifocal Lenses- correct for multiple distance points (distance and reading)
Bifocal Lens
A lens that has 2 powers: usually one for correcting distance vision and one for correcting near vision
Trifocal Lens
One that has 3 powers: one for correcting distance vision, one for correcting intermediate vision, and one for correcting near vision
Segment
The portion of the bifocal or multifocal lens that provides correction for near vision
Also called Segment or Near Add
Executive
Refers to a bifocal lens consisting of a top distance band and bottom near band that divides the entire width of lens into 2 parts
Also called lined bifocal
Advantage: very clear which portion of the lens a patient needs to use for certain tasks
Round-Top Segments
A portion of a circle fused or ground into a distance lens for near vision; may be used in bifocal or trifocal
D Segment
A portion of bifocal or trifocal lens; so called because it is shaped like the letter D lying on its side
Progressive Addition Multifocal Lenses
A spectacle lens with multiple areas of different focal points with no discrete visible lens dividing the various segments; rather, the optical power is added progressively in a transitional manner
Advantages: clear vision at all distances, more fashionable
Invisible Bifocals
A bifocal lens with a softened or blended transitional zone between the segment and the distance portion
These are not the same as Progressive bifocals
Double-D Segment
A multifocal lens with the distance correction in the middle, a traditional near-power D segment at the bottom, and an intermediate-power inverted D segment at the top, commonly used by individuals with vocational needs for intermediate correction in upgaze such as mechanics and boaters
CR-39
A common plastic lens material with an index of refraction
Polycarbonate
A common plastic safety lens material that is resistant to shattering
Photochromic Lenses
Refers to a lens specially manufactured to be sensitive to ultraviolet light, so that it darkens in sunlight and lightens when not in sunlight
Polarized Lenses
A specialized lens that reduces glare from a horizontal reflecting surfaces and protects against UV rays
Antireflective Lens Treatments
A treatment that reduces or eliminates reflections from the surface of a lens
Interpupillary Distance
The distance from the center of one pupil to the center of the other pupil
Optical Center
The point of optimal vision; the single point of a lens through which light may pass without being bent or changed
Vertex Distance
The distance from the back surface of the lenses to the front surface of the eye
Measured by a distometer
Base Curve
The curve of the lens surface, usually the outer or front side of the lens, from which the other curves necessary for sight correction are calculated
Orthophoric
Refers to the absence of strabismic deviation; normal
Distance between Optical Centers
The distance between the optical center of the right eyeglass lens and the optical center of the left lens; Corresponds to interpupillary distance
Prismatic Effect
An optical distortion in which images are displaced from their normal position. This can occur if the distance between optical centers does not correspond to the interpupillary distance
Digital Corneal Reflection Pupillometer (DCRP)
An instrument that monocularly measures interpupillary distance
Distometer
An instrument that measures the vertex distance
Geneva Lens
An instrument for measuring the base curve of an eyeglass lens
Pantoscopic Angle
The angle of an eyeglass frame by which the frame front tilts from the vertical plane when the glasses are worn
Retroscopic Tilt
The tilt of an eyeglass frame adjusted so that the lower rim tilts away from the face
Segment Height
The distance between the lowest part of an eyeglass rim and the top of the multifocal lens segment
