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ABO NCLE CONTACT LENS TERMS EXAM
QUESTIONS AND ANSWERS || LATEST
2025/2026 || A GRADE
Abrasion, Corneal - (ANSWER)scraped area of corneal surface, accompanied by
loss of superficial tissue (epithelium)
Acanthamoeba keratitis - (ANSWER)A rare, but serious sight-destroying
inflammation of the cornea caused by the parasite fount in contaminated water
accommodation - (ANSWER)the ability of the crystalline lens to adjust power to
provide retinal focus of images closer than optical infinity
Add - (ANSWER)Additional amount of plus power required for focusing at near
Albinism - (ANSWER)congenital absence or deficiency of pigment in the iris, skin,
and/or hair; usually associated with lowered visual acuity, nystagmus, and
photophobia and often accompanied by large refractive errors
ambloypia - (ANSWER)Loss of vision without any apparent disease of the eye
ametropia - (ANSWER)A refractive error in which the eye, when in a state of rest,
does not focus the image of an object upon the retina; includes hyperopia,
myopia, and astigmatism.
, 2
anomaly - (ANSWER)deviation from what is normal
Anterior Bevel/CN Bevel - (ANSWER)Angulation applied to the anterior surface of
a lens to reduce edge Thickness
Anterior Optical Zone (AOZ) - (ANSWER)Diameter of the anterior power curve
aphakia - (ANSWER)Absence of the crystalline lens
Apical (apex) - (ANSWER)The extreme top or tip of a curve, e.g. corneal apex.
Apical bearing, apical touch - (ANSWER)The posterior lens curvature resting on
the corneal apex.
aqueous humor - (ANSWER)clear, watery fluid that fills the space between the
back corneal surface and the front vitreous surface, bathing the crystalline lens.
Produced by the ciliary processes; nourishes the cornea, iris, and lens and
maintains intraocular pressure
Aqueous tears - (ANSWER)The middle layer of the tear film. The watery
component of the tears
Arbor - (ANSWER)A brass tool that holds a lens or lens blank in place for cutting
the surface or polishing
, 3
Arcuate stain - (ANSWER)An arc shaped corneal abrasion caused by the edge of a
contact lens
Aspheric - (ANSWER)Not spherical. A posterior or anterior lens surface design
which flattens at a given rate (eccentricity) as the curve progresses toward the
periphery.
Aspheric lens - (ANSWER)a lens that resembles an ellipse, parabola, or other
conic section rather than a sphere. It can be designed to improve the fit and
comfort of a lens by paralleling the cornea more closely or to provide progressive
bifocal effect
astigmatism - (ANSWER)defective curvature of the cornea or lens of the eye
Axial edge lift - (ANSWER)Vertical distance from the lens edge to an extension of
the base curve of a lens.
Axis, cylinder - (ANSWER)The weakest, or least curved, meridian on the surface of
a cylindrical or toric surface.
Axis, principal - (ANSWER)An imaginary line going through the geometric center
of an optical system, perpendicular to the surface.
, 4
Back toric - (ANSWER)A lens design with two principal curves at right angles to
each other on the lens posterior
Back Vertex Power (BVP) - (ANSWER)the power of the lens when it is oriented
such as when light enters the anterior surface and exits the posterior surface. It is
when the lens is positioned with the back curve (concave) is position against the
lens the lens stop of a lensometer
Bandage lens - (ANSWER)Soft contact lens used for protecting damaged or
irregular corneal surfaces.
Base curve - (ANSWER)of a contact lens, the curvature of the posterior optical
portion, otherwise known as the Central Posterior Curve (C.P.C)
Bell's phenomenon - (ANSWER)Upward and outward deviation of the eyes
occurring in sleep or with forcible closure of the eyelids.
benzyl alcohol - (ANSWER)A disinfectant and preservative in rigid lens solutions
Bicurve lens - (ANSWER)A lens consisting of two posterior curvatures; one central
curve (base curve) and one peripheral curve.
binocular - (ANSWER)Referring to or affecting both eyes
ABO NCLE CONTACT LENS TERMS EXAM
QUESTIONS AND ANSWERS || LATEST
2025/2026 || A GRADE
Abrasion, Corneal - (ANSWER)scraped area of corneal surface, accompanied by
loss of superficial tissue (epithelium)
Acanthamoeba keratitis - (ANSWER)A rare, but serious sight-destroying
inflammation of the cornea caused by the parasite fount in contaminated water
accommodation - (ANSWER)the ability of the crystalline lens to adjust power to
provide retinal focus of images closer than optical infinity
Add - (ANSWER)Additional amount of plus power required for focusing at near
Albinism - (ANSWER)congenital absence or deficiency of pigment in the iris, skin,
and/or hair; usually associated with lowered visual acuity, nystagmus, and
photophobia and often accompanied by large refractive errors
ambloypia - (ANSWER)Loss of vision without any apparent disease of the eye
ametropia - (ANSWER)A refractive error in which the eye, when in a state of rest,
does not focus the image of an object upon the retina; includes hyperopia,
myopia, and astigmatism.
, 2
anomaly - (ANSWER)deviation from what is normal
Anterior Bevel/CN Bevel - (ANSWER)Angulation applied to the anterior surface of
a lens to reduce edge Thickness
Anterior Optical Zone (AOZ) - (ANSWER)Diameter of the anterior power curve
aphakia - (ANSWER)Absence of the crystalline lens
Apical (apex) - (ANSWER)The extreme top or tip of a curve, e.g. corneal apex.
Apical bearing, apical touch - (ANSWER)The posterior lens curvature resting on
the corneal apex.
aqueous humor - (ANSWER)clear, watery fluid that fills the space between the
back corneal surface and the front vitreous surface, bathing the crystalline lens.
Produced by the ciliary processes; nourishes the cornea, iris, and lens and
maintains intraocular pressure
Aqueous tears - (ANSWER)The middle layer of the tear film. The watery
component of the tears
Arbor - (ANSWER)A brass tool that holds a lens or lens blank in place for cutting
the surface or polishing
, 3
Arcuate stain - (ANSWER)An arc shaped corneal abrasion caused by the edge of a
contact lens
Aspheric - (ANSWER)Not spherical. A posterior or anterior lens surface design
which flattens at a given rate (eccentricity) as the curve progresses toward the
periphery.
Aspheric lens - (ANSWER)a lens that resembles an ellipse, parabola, or other
conic section rather than a sphere. It can be designed to improve the fit and
comfort of a lens by paralleling the cornea more closely or to provide progressive
bifocal effect
astigmatism - (ANSWER)defective curvature of the cornea or lens of the eye
Axial edge lift - (ANSWER)Vertical distance from the lens edge to an extension of
the base curve of a lens.
Axis, cylinder - (ANSWER)The weakest, or least curved, meridian on the surface of
a cylindrical or toric surface.
Axis, principal - (ANSWER)An imaginary line going through the geometric center
of an optical system, perpendicular to the surface.
, 4
Back toric - (ANSWER)A lens design with two principal curves at right angles to
each other on the lens posterior
Back Vertex Power (BVP) - (ANSWER)the power of the lens when it is oriented
such as when light enters the anterior surface and exits the posterior surface. It is
when the lens is positioned with the back curve (concave) is position against the
lens the lens stop of a lensometer
Bandage lens - (ANSWER)Soft contact lens used for protecting damaged or
irregular corneal surfaces.
Base curve - (ANSWER)of a contact lens, the curvature of the posterior optical
portion, otherwise known as the Central Posterior Curve (C.P.C)
Bell's phenomenon - (ANSWER)Upward and outward deviation of the eyes
occurring in sleep or with forcible closure of the eyelids.
benzyl alcohol - (ANSWER)A disinfectant and preservative in rigid lens solutions
Bicurve lens - (ANSWER)A lens consisting of two posterior curvatures; one central
curve (base curve) and one peripheral curve.
binocular - (ANSWER)Referring to or affecting both eyes
