3: refractive status



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3: REFRACTIVE STATUS


  1. The eye is said to have a refractive error when __________.

  1. light rays do not bend properly to form a single-point focus on the retina

  2. a person is unable to wear contact lenses

  3. parallel light rays are appropriately refracted to focus on the retina

  4. light rays are unable to pass through the cornea




  1. The index of refraction is abbreviated by the symbol ________.

  1. i

  2. n

  3. r

  4. v




  1. A light ray traveling from one medium to another medium that has a higher index of refraction will be ____________.

  1. bent away from the normal

  2. perpendicular

  3. bent toward the normal

  4. unaffected

4. Divergence occurs when the light rays _________.



  1. bend toward the midline

  2. do not bend

  3. enter “optical infinity”

  4. bend away from the midline

5. There is no refraction of light at _________.



  1. the optical center

  2. the index of refraction

  3. 20 feet

  4. the angle of incidence




    1. Light rays assume a virtually parallel course, or “optical infinity,” at approximately

  1. 20 m

  2. 20 miles

  3. 20 cm

  4. 20 feet




    1. Convex lenses are also referred to as _________.

  1. plano lenses

  2. plus lenses

  3. minus lenses

  4. astigmatism lenses




    1. A lens in which the center is thinner than its edges is known as ____________.

  1. concave

  2. compound

  3. convex

  4. plano




    1. Light rays entering the eye must first pass through the _____________.

  1. retina

  2. limbus

  3. crystalline lens

  4. cornea




    1. Which structure contributes approximately 70% of the optical power of the eye?

  1. crystalline lens

  2. retina

  3. posterior pole

  4. cornea




    1. Combining front and back surface powers, the total power of the cornea averages approximately __________.

  1. 12.00 D

  2. 22.00 D

  3. 32.00 D

  4. 42.00 D




    1. Which part of the eye is biconvex, normally transparent, and sits just behind the iris?

  1. retina

  2. cornea

  3. crystalline lens

  4. sclera




    1. Accommodation is defined as _____________.

  1. light rays entering the eye

  2. the act of the crystalline lens changing its shape to focus for objects at varying distances

  3. the refracting power of the cornea

  4. a reductions of visual acuity with no apparent cause



    1. The number of diopters of power is equal to the reciprocal of the focal length of a lens in ________.

  1. meters

  2. centimeters

  3. inches

  4. feet




    1. A 3.00 D lens has the focal length of _______.

  1. 3 m

  2. 0.50 m

  3. 50 cm

  4. 33 cm




    1. The ability of the crystalline lens to focus is known as ______________.

  1. accommodative reserve

  2. amplitude of accommodation

  3. refractive error

  4. accommodative insufficiency




    1. Accommodative reserve is the difference between _____________.

  1. supply and demand

  2. distance and diopters

  3. convergence and divergence

  4. power and refraction




    1. There are approximately 130 million of which of the following in the human retina?

  1. parallel rays

  2. rods

  3. diopters

  4. cones

    1. Cones in the human retina provide which of the following?

  1. peripheral vision

  2. scotopic vision

  3. color vision

  4. depth perception




    1. The area of the retina that provides the most acute vision is the _________.

    1. Posterior pole

    2. Crystalline lens

    3. Optic disc

    4. Fovea centralis




    1. What is the length of the eyeball from the cornea to the posterior pole known as?

  1. foveal length

  2. axial length

  3. emmetropic length

  4. ametropic length




    1. Axial length discrepancies will result in producing a (n) ___________.

    1. refractive error

    2. decrease in rods

    3. accommodative reserve

    4. electrophysiologic impulse




    1. In an emmetropic eye, where are parallel light rays affected?

  1. behind the retina

  2. in front of and behind the retina

  3. on the retina

  4. in front of the retina

    1. Myopia is commonly called __________.

  1. Farsightedness

  2. Pincushion

  3. Nearsightedness

  4. refractive index




    1. Concave lenses would be used to correct __________.

  1. Emmetropia

  2. Myopia

  3. Hyperopia

  4. presbyopia




    1. Minus lenses may cause _____________.

  1. magnified distortion

  2. pincushion distortion

  3. no distortion

  4. barrel distortion




    1. How are light rays refracted in hyperopia?

  1. in front of the retina

  2. directly on the retina

  3. behind the retina

  4. both in front and on the retina




    1. Hyperopia is closely connected with which one of the following?

  1. astigmatism

  2. retinoscopy

  3. accommodation

  4. anisometropia



    1. Treatment for hyperopia is usually with which one of the following?

  1. toric lenses

  2. convex lenses

  3. concave lenses

  4. complex lenses




    1. What is the distance called between two lines of focus called?

  1. interval of meridian

  2. interval of Sturm

  3. circle of least confusion

  4. axial length




    1. The difference between total ocular astigmatism and corneal astigmatism is called ___________.

  1. against-the-rule astigmatism

  2. residual astigmatism

  3. keratoconus astigmatism

  4. irregular astigmatism




    1. In mixed astigmatism, the focal lines are ________________.

  1. both on the retina

  2. both behind the retina

  3. located one in front of the retina and one behind the retina

  4. located one on the retina and one in front of the retina



    1. What type of lens is used for correction of compound astigmatism?

  1. Spherocylinder

  2. Concave

  3. Bifocal

  4. Convex




    1. A normal reduction in the ability to accommodate is known as ___________.

  1. Myopia

  2. Presbyopia

  3. Emmetropia

  4. Hyperopia




    1. What is the distinction between hyperopia and presbyopia?

  1. accommodative reserve

  2. axial length

  3. accommodative amplitude

  4. refractive error




    1. Who is credited with inventing bifocals?

  1. John Adams

  2. Benjamin Franklin

  3. Alexander Graham Bell

  4. Thomas Edison




    1. What is the most prevalent type of cataract?

  1. traumatic

  2. congenital

  3. secondary

  4. senile



    1. What is aphakia

  1. the presence of refractive error

  2. the presence of a cataract

  3. the absence of the crystalline

  4. the absence of accommodation




    1. Which of the following is not a treatment method for aphakia?

  1. spectacle lens correction

  2. corneal transplant

  3. contact lenses

  4. intraocular lens implant




    1. What is the condition of an unequal refractive state of two eyes known as?

    1. Antimetropia

    2. Anisometropia

    3. Emmetropia

    4. Aniseikonia




    1. Which is not a type of anisometropia?

  1. simple

  2. unequal

  3. compound

  4. mixed




    1. How is refractive anisometropia best corrected?

  1. contact lenses

  2. vision therapy

  3. surgery

  4. spectacle lenses


    1. What instrument is used in the clinical measurement of aniseikonia?

  1. eikonometer

  2. keratometer

  3. phoropter

  4. tonometer




    1. The difference in the size of two retinal images is known as ___________.

  1. antimetropia

  2. anisometropia

  3. anisocoria

  4. aniseikonia




    1. Lenses specifically designed to alleviate aniseikonia are called __________.

  1. isotonic lenses

  2. aphakic lenses

  3. keratoconic lenses

  4. iseikonic lenses




    1. Which is not a major category of amblyopia?

  1. refractive amblyopia

  2. traumatic amblyopia

  3. organic amblyopia

  4. strabismic amblyopia



    1. Strabismic amblyopia, or “lazy eye,” is most likely the result of which one of the following?

  1. Cataracts

  2. Trauma

  3. inherent aniseikonia

  4. abnormal binocularity




    1. What is another name for strabismic amblyopia?

  1. Abnormal binocularity

  2. Refractive amblyopia

  3. Amblyopia ex anopsia

  4. hemanopsia




    1. Refractive amblyopia is associated with what?

  1. Uncorrected Exotropia

  2. Uncorrected refractive error

  3. Corrected Esotropia

  4. Corrected Anisocoria

50. In the absence of stimuli which of the following may occur?



  1. Receptors may not develop properly

  2. Full visual capability may not be achieved

  3. None of the above

  4. All of the above


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