|3: REFRACTIVE STATUS
The eye is said to have a refractive error when __________.
light rays do not bend properly to form a single-point focus on the retina
a person is unable to wear contact lenses
parallel light rays are appropriately refracted to focus on the retina
light rays are unable to pass through the cornea
The index of refraction is abbreviated by the symbol ________.
A light ray traveling from one medium to another medium that has a higher index of refraction will be ____________.
bent away from the normal
bent toward the normal
4. Divergence occurs when the light rays _________.
bend toward the midline
do not bend
enter “optical infinity”
bend away from the midline
5. There is no refraction of light at _________.
the optical center
the index of refraction
the angle of incidence
Light rays assume a virtually parallel course, or “optical infinity,” at approximately
Convex lenses are also referred to as _________.
A lens in which the center is thinner than its edges is known as ____________.
Light rays entering the eye must first pass through the _____________.
Which structure contributes approximately 70% of the optical power of the eye?
Combining front and back surface powers, the total power of the cornea averages approximately __________.
Which part of the eye is biconvex, normally transparent, and sits just behind the iris?
Accommodation is defined as _____________.
light rays entering the eye
the act of the crystalline lens changing its shape to focus for objects at varying distances
the refracting power of the cornea
a reductions of visual acuity with no apparent cause
The number of diopters of power is equal to the reciprocal of the focal length of a lens in ________.
A 3.00 D lens has the focal length of _______.
The ability of the crystalline lens to focus is known as ______________.
amplitude of accommodation
Accommodative reserve is the difference between _____________.
supply and demand
distance and diopters
convergence and divergence
power and refraction
There are approximately 130 million of which of the following in the human retina?
Cones in the human retina provide which of the following?
The area of the retina that provides the most acute vision is the _________.
What is the length of the eyeball from the cornea to the posterior pole known as?
Axial length discrepancies will result in producing a (n) ___________.
decrease in rods
In an emmetropic eye, where are parallel light rays affected?
behind the retina
in front of and behind the retina
on the retina
in front of the retina
Myopia is commonly called __________.
Concave lenses would be used to correct __________.
Minus lenses may cause _____________.
How are light rays refracted in hyperopia?
in front of the retina
directly on the retina
behind the retina
both in front and on the retina
Hyperopia is closely connected with which one of the following?
Treatment for hyperopia is usually with which one of the following?
What is the distance called between two lines of focus called?
interval of meridian
interval of Sturm
circle of least confusion
The difference between total ocular astigmatism and corneal astigmatism is called ___________.
In mixed astigmatism, the focal lines are ________________.
both on the retina
both behind the retina
located one in front of the retina and one behind the retina
located one on the retina and one in front of the retina
What type of lens is used for correction of compound astigmatism?
A normal reduction in the ability to accommodate is known as ___________.
What is the distinction between hyperopia and presbyopia?
Who is credited with inventing bifocals?
Alexander Graham Bell
What is the most prevalent type of cataract?
What is aphakia
the presence of refractive error
the presence of a cataract
the absence of the crystalline
the absence of accommodation
Which of the following is not a treatment method for aphakia?
spectacle lens correction
intraocular lens implant
What is the condition of an unequal refractive state of two eyes known as?
Which is not a type of anisometropia?
How is refractive anisometropia best corrected?
What instrument is used in the clinical measurement of aniseikonia?
The difference in the size of two retinal images is known as ___________.
Lenses specifically designed to alleviate aniseikonia are called __________.
Which is not a major category of amblyopia?
Strabismic amblyopia, or “lazy eye,” is most likely the result of which one of the following?
What is another name for strabismic amblyopia?
Amblyopia ex anopsia
Refractive amblyopia is associated with what?
Uncorrected refractive error
50. In the absence of stimuli which of the following may occur?
Receptors may not develop properly
Full visual capability may not be achieved
None of the above
All of the above