Download 3: refractive status - Lynn`s Lecture Help

3: REFRACTIVE STATUS
1. The eye is said to have a refractive error when
__________.
a. light rays do not bend properly to form a singlepoint focus on the retina
b. a person is unable to wear contact lenses
c. parallel light rays are appropriately refracted to
focus on the retina
d. light rays are unable to pass through the cornea
2. The index of refraction is abbreviated by the symbol
________.
a. i
b. n
c. r
d. v
3. A light ray traveling from one medium to another medium
that has a higher index of refraction will be ____________.
a. bent away from the normal
b. perpendicular
c. bent toward the normal
d. unaffected
4. Divergence occurs when the light rays _________.
a. bend toward the midline
b. do not bend
c. enter “optical infinity”
d. bend away from the midline
5. There is no refraction of light at _________.
a. the optical center
b. the index of refraction
c. 20 feet
d. the angle of incidence
6. Light rays assume a virtually parallel course, or “optical
infinity,” at approximately
a. 20 m
b. 20 miles
c. 20 cm
d. 20 feet
7. Convex lenses are also referred to as _________.
a. plano lenses
b. plus lenses
c. minus lenses
d. astigmatism lenses
8. A lens in which the center is thinner than its edges is
known as ____________.
a. concave
b. compound
c. convex
d. plano
9. Light rays entering the eye must first pass through the
_____________.
a. retina
b. limbus
c. crystalline lens
d. cornea
10. Which structure contributes approximately 70% of the
optical power of the eye?
a. crystalline lens
b. retina
c. posterior pole
d. cornea
14. The number of diopters of power is equal to the reciprocal
of the focal length of a lens in ________.
a. meters
b. centimeters
c. inches
d. feet
11. Combining front and back surface powers, the total power
of the cornea averages approximately __________.
a. 12.00 D
b. 22.00 D
c. 32.00 D
d. 42.00 D
15. A 3.00 D lens has the focal length of _______.
a. 3 m
b. 0.50 m
c. 50 cm
d. 33 cm
12. Which part of the eye is biconvex, normally transparent,
and sits just behind the iris?
a. retina
b. cornea
c. crystalline lens
d. sclera
13. Accommodation is defined as _____________.
a. light rays entering the eye
b. the act of the crystalline lens changing its shape
to focus for objects at varying distances
c. the refracting power of the cornea
d. a reductions of visual acuity with no apparent
cause
16. The ability of the crystalline lens to focus is known as
______________.
a. accommodative reserve
b. amplitude of accommodation
c. refractive error
d. accommodative insufficiency
17. Accommodative reserve is the difference between
_____________.
a. supply and demand
b. distance and diopters
c. convergence and divergence
d. power and refraction
18. There are approximately 130 million of which of the
following in the human retina?
a. parallel rays
b. rods
c. diopters
d. cones
19. Cones in the human retina provide which of the following?
a. peripheral vision
b. scotopic vision
c. color vision
d. depth perception
24. Myopia is commonly called __________.
a. Farsightedness
b. Pincushion
c. Nearsightedness
d. refractive index
20. The area of the retina that provides the most acute vision is
the _________.
a. Posterior pole
b. Crystalline lens
c. Optic disc
d. Fovea centralis
25. Concave lenses would be used to correct __________.
a. Emmetropia
b. Myopia
c. Hyperopia
d. presbyopia
21. What is the length of the eyeball from the cornea to the
posterior pole known as?
a. foveal length
b. axial length
c. emmetropic length
d. ametropic length
22. Axial length discrepancies will result in producing a (n)
___________.
a. refractive error
b. decrease in rods
c. accommodative reserve
d. electrophysiologic impulse
23. In an emmetropic eye, where are parallel light rays
affected?
a. behind the retina
b. in front of and behind the retina
c. on the retina
d. in front of the retina
26. Minus lenses may cause _____________.
a. magnified distortion
b. pincushion distortion
c. no distortion
d. barrel distortion
27. How are light rays refracted in hyperopia?
a. in front of the retina
b. directly on the retina
c. behind the retina
d. both in front and on the retina
28. Hyperopia is closely connected with which one of the
following?
a. astigmatism
b. retinoscopy
c. accommodation
d. anisometropia
29. Treatment for hyperopia is usually with which one of the
following?
a. toric lenses
b. convex lenses
c. concave lenses
d. complex lenses
33. What type of lens is used for correction of compound
astigmatism?
a. Spherocylinder
b. Concave
c. Bifocal
d. Convex
30. What is the distance called between two lines of focus
called?
a. interval of meridian
b. interval of Sturm
c. circle of least confusion
d. axial length
34. A normal reduction in the ability to accommodate is known
as ___________.
a. Myopia
b. Presbyopia
c. Emmetropia
d. Hyperopia
31. The difference between total ocular astigmatism and
corneal astigmatism is called ___________.
a. against-the-rule astigmatism
b. residual astigmatism
c. keratoconus astigmatism
d. irregular astigmatism
35. What is the distinction between hyperopia and presbyopia?
a. accommodative reserve
b. axial length
c. accommodative amplitude
d. refractive error
32. In mixed astigmatism, the focal lines are
________________.
a. both on the retina
b. both behind the retina
c. located one in front of the retina and one behind
the retina
d. located one on the retina and one in front of the
retina
36. Who is credited with inventing bifocals?
a. John Adams
b. Benjamin Franklin
c. Alexander Graham Bell
d. Thomas Edison
37. What is the most prevalent type of cataract?
a. traumatic
b. congenital
c. secondary
d. senile
38. What is aphakia
a. the presence of refractive error
b. the presence of a cataract
c. the absence of the crystalline
d. the absence of accommodation
39. Which of the following is not a treatment method for
aphakia?
a. spectacle lens correction
b. corneal transplant
c. contact lenses
d. intraocular lens implant
40. What is the condition of an unequal refractive state of two
eyes known as?
a. Antimetropia
b. Anisometropia
c. Emmetropia
d. Aniseikonia
41. Which is not a type of anisometropia?
a. simple
b. unequal
c. compound
d. mixed
42. How is refractive anisometropia best corrected?
a. contact lenses
b. vision therapy
c. surgery
d. spectacle lenses
43. What instrument is used in the clinical measurement of
aniseikonia?
a. eikonometer
b. keratometer
c. phoropter
d. tonometer
44. The difference in the size of two retinal images is known as
___________.
a. antimetropia
b. anisometropia
c. anisocoria
d. aniseikonia
45. Lenses specifically designed to alleviate aniseikonia are
called __________.
a. isotonic lenses
b. aphakic lenses
c. keratoconic lenses
d. iseikonic lenses
46. Which is not a major category of amblyopia?
a. refractive amblyopia
b. traumatic amblyopia
c. organic amblyopia
d. strabismic amblyopia
47. Strabismic amblyopia, or “lazy eye,” is most likely the
result of which one of the following?
a. Cataracts
b. Trauma
c. inherent aniseikonia
d. abnormal binocularity
48. What is another name for strabismic amblyopia?
a. Abnormal binocularity
b. Refractive amblyopia
c. Amblyopia ex anopsia
d. hemanopsia
49. Refractive amblyopia is associated with what?
a. Uncorrected Exotropia
b. Uncorrected refractive error
c. Corrected Esotropia
d. Corrected Anisocoria
50. In the absence of stimuli which of the following may
occur?
a. Receptors may not develop properly
b. Full visual capability may not be achieved
c. None of the above
d. All of the above