NCLE Practice Test Questions with
Complete Solutions16
base curve - ANSWERS-refers to the radius of curvature of the central posterior surface of the
lens. It may be expressed in diopters of surface power (D) or in millimeters (mm) of radius or
curvature.
optical zone - ANSWERS-the chord diameter over which the base curve extends on the posterior
surface of the contact lens, described in millimeters
secondary or intermediate curves - ANSWERS-lies between the base curve and the peripheral
curve on the posterior lens surface, usually 0.70mm to 1.50mm flatter than the base curve
radius, this allows the lens to better align the flatter portion of the cornea adjacent to the
optical zone
peripheral curve - ANSWERS-the outermost curve on the posterior lens surface, its function is to
clear the flatter periphery of the cornea and to prevent lens impingement in the limbal areas as
the lens moves with blinking
blend curve - ANSWERS-the treatment given to the sharp junctions created by the difference in
the radii of curvature between the base curve, the secondary curve, and the peripheral curve,
rarely required at the base curve/secondary curve junction.
lens diameter - ANSWERS-refers to the overall width of the lens from one edge to the other, it is
measured in millimeters. Normal ranges are from 7.00mm to 10.50mm in rigid lenses and from
12.50mm to 16.00mm in soft contacts
,center thickness - ANSWERS-the measurement in millimeters from the anterior to the posterior
surface of the lens at its geometric center, this measurement varies significantly depending on
the power of the lens
anterior - ANSWERS-nearer the front, especially situated in the front of the body or nearer to
the head
posterior - ANSWERS-further back in position; of or nearer the rear or hind end, especially of
the body or a part of it.
lens power - ANSWERS-the difference between the radii of the anterior and posterior lens
surface
abrasion - ANSWERS-rubbing off of the superficial layer
accommodation - ANSWERS-adjustment by the eye for seeing different distances, accomplished
by changing the shape of the crystalline lens through action of the ciliary muscle
acuity - ANSWERS-clearness; measured by the smallest object that can seen at a certain
distance
adnexa oculi - ANSWERS-accessory structures of the eye, such as lacrimal apparatus and the eye
lids
albinism - ANSWERS-hereditary loss of pigment in the eye, skin & hair; usually associated with
lowered visual acuity, nystagmus & light sensitivity
amblyopia - ANSWERS-loss of vision with any apparent disease of the eye
, ametropia - ANSWERS-a refractive error in which the eye, when in state of rest, does not focus
the image of an object upon the retina; includes hyperopia,myopia and astigmatism
aniridia - ANSWERS-congenital absence of the iris
aniseikonia - ANSWERS-a condition in which the ocular image of an object as seen by one eye
differs so much in size or shape from the seen by the other eye that the two images cannot be
fused into a single impression
aniscoria - ANSWERS-inequality of the pupils in diameter
anomaly - ANSWERS-departure from the normal
anopthalmia - ANSWERS-absence of a true eyeball
anterior chamber - ANSWERS-space in front of the eye, bounded in front by the cornea and
behind by the iris; filled with aqueous humor
antibody - ANSWERS-a specific substance produced by the body in the presence of an antigen
antigen - ANSWERS-any substance that acts against the action of histamine
aphakia - ANSWERS-absence of the crystalline lens of the eye
aqueous humor - ANSWERS-clear, watery fluid that fills the anterior and posterior chambers
within the front part of the eye
arcus senilus - ANSWERS-grayish white ring in the periphery of the cornea
Complete Solutions16
base curve - ANSWERS-refers to the radius of curvature of the central posterior surface of the
lens. It may be expressed in diopters of surface power (D) or in millimeters (mm) of radius or
curvature.
optical zone - ANSWERS-the chord diameter over which the base curve extends on the posterior
surface of the contact lens, described in millimeters
secondary or intermediate curves - ANSWERS-lies between the base curve and the peripheral
curve on the posterior lens surface, usually 0.70mm to 1.50mm flatter than the base curve
radius, this allows the lens to better align the flatter portion of the cornea adjacent to the
optical zone
peripheral curve - ANSWERS-the outermost curve on the posterior lens surface, its function is to
clear the flatter periphery of the cornea and to prevent lens impingement in the limbal areas as
the lens moves with blinking
blend curve - ANSWERS-the treatment given to the sharp junctions created by the difference in
the radii of curvature between the base curve, the secondary curve, and the peripheral curve,
rarely required at the base curve/secondary curve junction.
lens diameter - ANSWERS-refers to the overall width of the lens from one edge to the other, it is
measured in millimeters. Normal ranges are from 7.00mm to 10.50mm in rigid lenses and from
12.50mm to 16.00mm in soft contacts
,center thickness - ANSWERS-the measurement in millimeters from the anterior to the posterior
surface of the lens at its geometric center, this measurement varies significantly depending on
the power of the lens
anterior - ANSWERS-nearer the front, especially situated in the front of the body or nearer to
the head
posterior - ANSWERS-further back in position; of or nearer the rear or hind end, especially of
the body or a part of it.
lens power - ANSWERS-the difference between the radii of the anterior and posterior lens
surface
abrasion - ANSWERS-rubbing off of the superficial layer
accommodation - ANSWERS-adjustment by the eye for seeing different distances, accomplished
by changing the shape of the crystalline lens through action of the ciliary muscle
acuity - ANSWERS-clearness; measured by the smallest object that can seen at a certain
distance
adnexa oculi - ANSWERS-accessory structures of the eye, such as lacrimal apparatus and the eye
lids
albinism - ANSWERS-hereditary loss of pigment in the eye, skin & hair; usually associated with
lowered visual acuity, nystagmus & light sensitivity
amblyopia - ANSWERS-loss of vision with any apparent disease of the eye
, ametropia - ANSWERS-a refractive error in which the eye, when in state of rest, does not focus
the image of an object upon the retina; includes hyperopia,myopia and astigmatism
aniridia - ANSWERS-congenital absence of the iris
aniseikonia - ANSWERS-a condition in which the ocular image of an object as seen by one eye
differs so much in size or shape from the seen by the other eye that the two images cannot be
fused into a single impression
aniscoria - ANSWERS-inequality of the pupils in diameter
anomaly - ANSWERS-departure from the normal
anopthalmia - ANSWERS-absence of a true eyeball
anterior chamber - ANSWERS-space in front of the eye, bounded in front by the cornea and
behind by the iris; filled with aqueous humor
antibody - ANSWERS-a specific substance produced by the body in the presence of an antigen
antigen - ANSWERS-any substance that acts against the action of histamine
aphakia - ANSWERS-absence of the crystalline lens of the eye
aqueous humor - ANSWERS-clear, watery fluid that fills the anterior and posterior chambers
within the front part of the eye
arcus senilus - ANSWERS-grayish white ring in the periphery of the cornea
