NCLE basic contact lense design| 58 questions| WITH COMPLETE SOLUTION
optic zone Correct Answer: The central portion of a contact lens which contains the refractive
power and generally corresponds to the central corneal cap
Posterior Apecal Radius Correct Answer: this term is generally used in reference to spin-cast
soft lenses. the curvature of the posterior surface of the lens changes with the refractive power.
The radius of curvature is measured at the apex of the posterior surface.
Bicurve lens Correct Answer: A contact lens which contains two curves: one base curve and one
secondary curve. It is usually small (7.5 to 8.8 mm in diameter), relatively steep, and made with
narrow peripheral curves (about 0.2 mm). Bicurve rigid lenses are usually intrapalpebral lenses,
designed to fit within the palpebral fissure limits.
gas permeable lenses Correct Answer: Contact lenses that allow oxygen and carbon dioxide to
pass through them. Usually refers to a type of hard lens (RPG), although soft lenses are also gas
permeabler ewe] p
scleral (Haptic) lens Correct Answer: first successful contact lenses.
originally molded to conform to the shape of the cornea, newer lenses are lathe cut and made of
gas permeable materials.
very difficult to tolerate and are primarily used when other types of lenses would fail.
examples of cases where would be used are severe keratoconus, severe lid problems, and great
amount of astigmatism.
Corneal lens Correct Answer: most common design for rigid gas permeable lenses.
the diameter of the lens is less than that of the cornea.
Semi-Scleral Lens Correct Answer: a design typical of soft contact lenses
bridge the limbus and lie partially on the conjunctiva tissue overlaying the sclera adjacent to the
cornea.
Cosmetic Lens Correct Answer: Most Common lense used
used for people who don't want to wear glassses
can be used to cover an unsightly blind eye,
Hydrophobic lens Correct Answer: made if Material which, if not specifically treated will repel
water
, Wettig Angle Correct Answer: The angle that the edges of a bead of water make with the
surface of a given material.
The smaller the angle, the greater the wetting ability
Hydrophilic Lens Correct Answer: Made of materials which wil naturally absorb water
Base curve Correct Answer: centeral portion of the back surface of a contact lense.
also known as CenteralPosterior Curve (CPC) or Primary Base curve
Larger Circe of Sphere Correct Answer: Longer radius
Flatter Curve
Less Power
Centeral Posterior Curve (CPC) Correct Answer: Also known as Base Curve, or Primary Base
Curve.
Centeral Portion of the back surface of a contact lens
As Dipter power increases, MM distance ____ Correct Answer: decreases
Shorter Circle of Sphere Correct Answer: Shorter Radius of Curvature
Steeper Curve
More Power
rule of thumb Correct Answer: When the Power of curve changes by .50 dipters the radius of the
curvature changes aproximatly .10mm
radius of curvature Correct Answer: distance is the distance from the geometic center o the
circle to its perphery.
The size of diopter is ________ proportional to radius of curvature in mm Correct Answer:
Inversly
As the radius of curvature get longer the circle gets ________ Correct Answer: Larger
As the Radius Of curvature gets longer in MM The dipter power gets _____ Correct Answer:
Smaller, lower power
Sagittal Depth or Heights Correct Answer: The distance between a flat surface and the back
surface of the central portion of a lense.
A greater Saittal depth produces a greater _______ Correct Answer: Vaulting of the lens and in
effect the lens would be steeper.
optic zone Correct Answer: The central portion of a contact lens which contains the refractive
power and generally corresponds to the central corneal cap
Posterior Apecal Radius Correct Answer: this term is generally used in reference to spin-cast
soft lenses. the curvature of the posterior surface of the lens changes with the refractive power.
The radius of curvature is measured at the apex of the posterior surface.
Bicurve lens Correct Answer: A contact lens which contains two curves: one base curve and one
secondary curve. It is usually small (7.5 to 8.8 mm in diameter), relatively steep, and made with
narrow peripheral curves (about 0.2 mm). Bicurve rigid lenses are usually intrapalpebral lenses,
designed to fit within the palpebral fissure limits.
gas permeable lenses Correct Answer: Contact lenses that allow oxygen and carbon dioxide to
pass through them. Usually refers to a type of hard lens (RPG), although soft lenses are also gas
permeabler ewe] p
scleral (Haptic) lens Correct Answer: first successful contact lenses.
originally molded to conform to the shape of the cornea, newer lenses are lathe cut and made of
gas permeable materials.
very difficult to tolerate and are primarily used when other types of lenses would fail.
examples of cases where would be used are severe keratoconus, severe lid problems, and great
amount of astigmatism.
Corneal lens Correct Answer: most common design for rigid gas permeable lenses.
the diameter of the lens is less than that of the cornea.
Semi-Scleral Lens Correct Answer: a design typical of soft contact lenses
bridge the limbus and lie partially on the conjunctiva tissue overlaying the sclera adjacent to the
cornea.
Cosmetic Lens Correct Answer: Most Common lense used
used for people who don't want to wear glassses
can be used to cover an unsightly blind eye,
Hydrophobic lens Correct Answer: made if Material which, if not specifically treated will repel
water
, Wettig Angle Correct Answer: The angle that the edges of a bead of water make with the
surface of a given material.
The smaller the angle, the greater the wetting ability
Hydrophilic Lens Correct Answer: Made of materials which wil naturally absorb water
Base curve Correct Answer: centeral portion of the back surface of a contact lense.
also known as CenteralPosterior Curve (CPC) or Primary Base curve
Larger Circe of Sphere Correct Answer: Longer radius
Flatter Curve
Less Power
Centeral Posterior Curve (CPC) Correct Answer: Also known as Base Curve, or Primary Base
Curve.
Centeral Portion of the back surface of a contact lens
As Dipter power increases, MM distance ____ Correct Answer: decreases
Shorter Circle of Sphere Correct Answer: Shorter Radius of Curvature
Steeper Curve
More Power
rule of thumb Correct Answer: When the Power of curve changes by .50 dipters the radius of the
curvature changes aproximatly .10mm
radius of curvature Correct Answer: distance is the distance from the geometic center o the
circle to its perphery.
The size of diopter is ________ proportional to radius of curvature in mm Correct Answer:
Inversly
As the radius of curvature get longer the circle gets ________ Correct Answer: Larger
As the Radius Of curvature gets longer in MM The dipter power gets _____ Correct Answer:
Smaller, lower power
Sagittal Depth or Heights Correct Answer: The distance between a flat surface and the back
surface of the central portion of a lense.
A greater Saittal depth produces a greater _______ Correct Answer: Vaulting of the lens and in
effect the lens would be steeper.
