ABO Study Guide with all Correct & 100% Verified
Answers |Actual Complete Update |Already Graded A+
(Just Released)
Deviation from a single focus of light rays emanating from one source. ✔Correct Answer-
Aberration
The ability of the eye to adjust focus for varying distances. ✔Correct Answer-Accommodation
Descriptive of a lens capable of refracting light without creating a rainbow effect. ✔Correct
Answer-Achromatic
Visual expression of sharpness of vision. (20/20 distance, J.1 near) ✔Correct Answer-Acuity
Difference in plus power between the reading and distance portions of a multifocal lens.
✔Correct Answer-Addition
Loss of vision without any apparent disease of the eye. ✔Correct Answer-Amblyopia
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. ✔Correct Answer-
Ametropia
A condition in which the image of an object as seen by one eye differs so much in size or shape
from that seen by the other eye that the two images cannot be fused into a single impression.
✔Correct Answer-Aniseikonia
A condition in which the refractive error of one eye significantly differs from that of the other.
✔Correct Answer-Anisometropia
Front cavity or compartment of the eye, located between the cornea and crystalline lens.
Contains aqueous humor. ✔Correct Answer-Anterior Chamber
Thinnest edge of a prism. ✔Correct Answer-Apex
An absence of the crystalline lens of the eye. (Pseudophakia: having a false lens) ✔Correct
Answer-Aphakia
Not spherical; a lens surface having a number of curves with different radii. ✔Correct Answer-
Aspheric
,A defect of the eye, of a lens or of an image formed by either, the curvature of the refracting
surface or the surfaces being different in different planes. This results in the focal lengths also
being different in different planes. (The curvature of the cornea in the case of the eye)
✔Correct Answer-Astigmatism
The meridian of no cylinder power in a spherocylinder lens. ✔Correct Answer-Axis
Thickest edge of a prism. ✔Correct Answer-Base
The curve used as a base of a series of powers; the degree of curvature of the front surface of a
lens. ✔Correct Answer-Base Curve
A group of parallel rays of light. ✔Correct Answer-Beam
Pertaining to vision with both eyes. ✔Correct Answer-Binocular
Instrument used to measure thickness, calibrated in fifths and tenths of a millimeter.
✔Correct Answer-Caliper
The angle at either end of the slit between the eyelids. ✔Correct Answer-Canthus
A condition when the crystalline lens of the eye becomes opaque. ✔Correct Answer-Cataract
One, which originates at birth. ✔Correct Answer-Congenital Cataract
The lens has become either solid and shrunken or soft and liquid. ✔Correct Answer-Hyper-
mature Cataract
Any cataract in its early stages. ✔Correct Answer-Incipient Cataract
The lens is completely opaque. ✔Correct Answer-Mature Cataract
A hard opacity of the lens occurring in the aged. ✔Correct Answer-Senile Cataract
Cataract following an injury. ✔Correct Answer-Traumatic Cataract
Vascular (blood-rich) layer of the eye; its function is to nourish the other parts of the eye,
primarily the retina. ✔Correct Answer-Choroid
Distortion of an optical image produced by the dispersion of light passing through a lens and
generally characterized by blurred, multicolored edges. ✔Correct Answer-Chromatic
Aberration
,The thick rim of choroid to which the crystalline lens is attached. ✔Correct Answer-Ciliary
Body
The refractive error which results in two points of focus falling behind the retina.
Ex: +1.00 / +2.00 x 090 ✔Correct Answer-Compound Hyperopic Astigmatism
The refractive error which results in two points of focus falling in front of the retina.
Ex: -1.00 / -2.00 x 090 ✔Correct Answer-Compound Myopic Astigmatism
Light sensitive cells in the retina responsible for color vision, daytime vision, and the central
portion of the visual field. ✔Correct Answer-Cones
The clear membrane that lines the eyelids and covers the exposed surface of the eyeball.
✔Correct Answer-Conjunctiva
The inflammation of the conjunctiva; commonly referred to as "pink eye". ✔Correct Answer-
Conjunctivitis
The refractive, transparent, anterior wall of the eye, equal to 43 diopters power. It is the fastest
healing part of the body. ✔Correct Answer-Cornea
Pure silicate glass of general excellence for the spectacle lens; index of refraction is 1.523.
✔Correct Answer-Crown Glass
A transparent colorless body suspended in the front part of the eyeball, between the aqueous
and the vitreous, the function of which is to bring the rays of light to a focus on the retina.
✔Correct Answer-Crystalline Lens
Paralysis of the ciliary body; drops are used for diagnostic purposes. ✔Correct Answer-
Cycloplegia
Distance between the optical center placement of a lens and its geometric center; usually
expressed in millimeters. ✔Correct Answer-Decentration
The scattering of light. ✔Correct Answer-Diffusion
Unit of measurement of the refractive power of a lens. A lens whose focal length is one meter
has a power of one. The higher the power, the shorter the focal length. ✔Correct Answer-
Diopter
The seeing of one object as two, due to uneven tracking of the eyes. Commonly known as
double vision. ✔Correct Answer-Diplopia
Defect in a lens which causes a straight line to appear curved. ✔Correct Answer-Distortion
, Two or more light rays proceeding outward from a point. ✔Correct Answer-Divergent
The refractive condition of the normal eye. When the eye is at rest, the image of distant objects
is brought to a focus on the retina. ✔Correct Answer-Emmetropia
A tendency for one eye to deviate off the visual axis toward the other eye. ✔Correct Answer-
Esophoria
Actual deviation of one eye toward the visual axis of the other eye. (Crossed eyes) ✔Correct
Answer-Esotropia
A tendency for one eye to deviate off the visual axis away from the other eye. ✔Correct
Answer-Exophoria
Actual deviation of one eye away from the visual axis of the other eye. (Walled eyes)
✔Correct Answer-Exotropia
Point in space which is sharply focused on the retina with the eye's accommodation relaxed.
✔Correct Answer-Far Point
A glass of high refractive index (1.65), containing lead. ✔Correct Answer-Flint Glass
The point in which the rays of a pencil of light converge or where they appear to diverge. In plus
lenses it is real; in minus lenses it is virtual. ✔Correct Answer-Focus
A small depression in the retina, at the back of the eye. It is the part of the macula adapted for
the clearest vision. ✔Correct Answer-Fovea
The power of coordination by which the images received by the two eyes become a single
image. ✔Correct Answer-Fusion
Point where the diagonals of a boxed lens meet. ✔Correct Answer-Geometric Center
An ocular disease having as it primary characteristic a sustained increase in intraocular pressure
that the eye cannot withstand without damage to its structure or impairment of its function.
Primary symptom is a loss of peripheral vision. ✔Correct Answer-Glaucoma
Also known as farsightedness. A refractive error in which, because the eyeball is short or the
refractive power of the lens is weak, the point of focus for rays of light from distant objects falls
behind the retina. Correction to increase refractive power (a plus lens) is necessary for distance
vision as well as near vision. ✔Correct Answer-Hyperopia
The ratio of the speed of light in air to the speed of light in a given medium.
Answers |Actual Complete Update |Already Graded A+
(Just Released)
Deviation from a single focus of light rays emanating from one source. ✔Correct Answer-
Aberration
The ability of the eye to adjust focus for varying distances. ✔Correct Answer-Accommodation
Descriptive of a lens capable of refracting light without creating a rainbow effect. ✔Correct
Answer-Achromatic
Visual expression of sharpness of vision. (20/20 distance, J.1 near) ✔Correct Answer-Acuity
Difference in plus power between the reading and distance portions of a multifocal lens.
✔Correct Answer-Addition
Loss of vision without any apparent disease of the eye. ✔Correct Answer-Amblyopia
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. ✔Correct Answer-
Ametropia
A condition in which the image of an object as seen by one eye differs so much in size or shape
from that seen by the other eye that the two images cannot be fused into a single impression.
✔Correct Answer-Aniseikonia
A condition in which the refractive error of one eye significantly differs from that of the other.
✔Correct Answer-Anisometropia
Front cavity or compartment of the eye, located between the cornea and crystalline lens.
Contains aqueous humor. ✔Correct Answer-Anterior Chamber
Thinnest edge of a prism. ✔Correct Answer-Apex
An absence of the crystalline lens of the eye. (Pseudophakia: having a false lens) ✔Correct
Answer-Aphakia
Not spherical; a lens surface having a number of curves with different radii. ✔Correct Answer-
Aspheric
,A defect of the eye, of a lens or of an image formed by either, the curvature of the refracting
surface or the surfaces being different in different planes. This results in the focal lengths also
being different in different planes. (The curvature of the cornea in the case of the eye)
✔Correct Answer-Astigmatism
The meridian of no cylinder power in a spherocylinder lens. ✔Correct Answer-Axis
Thickest edge of a prism. ✔Correct Answer-Base
The curve used as a base of a series of powers; the degree of curvature of the front surface of a
lens. ✔Correct Answer-Base Curve
A group of parallel rays of light. ✔Correct Answer-Beam
Pertaining to vision with both eyes. ✔Correct Answer-Binocular
Instrument used to measure thickness, calibrated in fifths and tenths of a millimeter.
✔Correct Answer-Caliper
The angle at either end of the slit between the eyelids. ✔Correct Answer-Canthus
A condition when the crystalline lens of the eye becomes opaque. ✔Correct Answer-Cataract
One, which originates at birth. ✔Correct Answer-Congenital Cataract
The lens has become either solid and shrunken or soft and liquid. ✔Correct Answer-Hyper-
mature Cataract
Any cataract in its early stages. ✔Correct Answer-Incipient Cataract
The lens is completely opaque. ✔Correct Answer-Mature Cataract
A hard opacity of the lens occurring in the aged. ✔Correct Answer-Senile Cataract
Cataract following an injury. ✔Correct Answer-Traumatic Cataract
Vascular (blood-rich) layer of the eye; its function is to nourish the other parts of the eye,
primarily the retina. ✔Correct Answer-Choroid
Distortion of an optical image produced by the dispersion of light passing through a lens and
generally characterized by blurred, multicolored edges. ✔Correct Answer-Chromatic
Aberration
,The thick rim of choroid to which the crystalline lens is attached. ✔Correct Answer-Ciliary
Body
The refractive error which results in two points of focus falling behind the retina.
Ex: +1.00 / +2.00 x 090 ✔Correct Answer-Compound Hyperopic Astigmatism
The refractive error which results in two points of focus falling in front of the retina.
Ex: -1.00 / -2.00 x 090 ✔Correct Answer-Compound Myopic Astigmatism
Light sensitive cells in the retina responsible for color vision, daytime vision, and the central
portion of the visual field. ✔Correct Answer-Cones
The clear membrane that lines the eyelids and covers the exposed surface of the eyeball.
✔Correct Answer-Conjunctiva
The inflammation of the conjunctiva; commonly referred to as "pink eye". ✔Correct Answer-
Conjunctivitis
The refractive, transparent, anterior wall of the eye, equal to 43 diopters power. It is the fastest
healing part of the body. ✔Correct Answer-Cornea
Pure silicate glass of general excellence for the spectacle lens; index of refraction is 1.523.
✔Correct Answer-Crown Glass
A transparent colorless body suspended in the front part of the eyeball, between the aqueous
and the vitreous, the function of which is to bring the rays of light to a focus on the retina.
✔Correct Answer-Crystalline Lens
Paralysis of the ciliary body; drops are used for diagnostic purposes. ✔Correct Answer-
Cycloplegia
Distance between the optical center placement of a lens and its geometric center; usually
expressed in millimeters. ✔Correct Answer-Decentration
The scattering of light. ✔Correct Answer-Diffusion
Unit of measurement of the refractive power of a lens. A lens whose focal length is one meter
has a power of one. The higher the power, the shorter the focal length. ✔Correct Answer-
Diopter
The seeing of one object as two, due to uneven tracking of the eyes. Commonly known as
double vision. ✔Correct Answer-Diplopia
Defect in a lens which causes a straight line to appear curved. ✔Correct Answer-Distortion
, Two or more light rays proceeding outward from a point. ✔Correct Answer-Divergent
The refractive condition of the normal eye. When the eye is at rest, the image of distant objects
is brought to a focus on the retina. ✔Correct Answer-Emmetropia
A tendency for one eye to deviate off the visual axis toward the other eye. ✔Correct Answer-
Esophoria
Actual deviation of one eye toward the visual axis of the other eye. (Crossed eyes) ✔Correct
Answer-Esotropia
A tendency for one eye to deviate off the visual axis away from the other eye. ✔Correct
Answer-Exophoria
Actual deviation of one eye away from the visual axis of the other eye. (Walled eyes)
✔Correct Answer-Exotropia
Point in space which is sharply focused on the retina with the eye's accommodation relaxed.
✔Correct Answer-Far Point
A glass of high refractive index (1.65), containing lead. ✔Correct Answer-Flint Glass
The point in which the rays of a pencil of light converge or where they appear to diverge. In plus
lenses it is real; in minus lenses it is virtual. ✔Correct Answer-Focus
A small depression in the retina, at the back of the eye. It is the part of the macula adapted for
the clearest vision. ✔Correct Answer-Fovea
The power of coordination by which the images received by the two eyes become a single
image. ✔Correct Answer-Fusion
Point where the diagonals of a boxed lens meet. ✔Correct Answer-Geometric Center
An ocular disease having as it primary characteristic a sustained increase in intraocular pressure
that the eye cannot withstand without damage to its structure or impairment of its function.
Primary symptom is a loss of peripheral vision. ✔Correct Answer-Glaucoma
Also known as farsightedness. A refractive error in which, because the eyeball is short or the
refractive power of the lens is weak, the point of focus for rays of light from distant objects falls
behind the retina. Correction to increase refractive power (a plus lens) is necessary for distance
vision as well as near vision. ✔Correct Answer-Hyperopia
The ratio of the speed of light in air to the speed of light in a given medium.
