CH 3 Refractive Status

• Strabismic amblyopia, or "lazy eye," is most likely the result of which one of the following?

  
  

  a) Cataract

  
  

  b) Trauma

  
  

  c) Inherent aniseikonia

  
  

  d) Abnormal binocularity

  d) Abnormal binocularity
• The eye is said to have a refractive error when:

  
  

  a) Light rays do not bend properly to form a single-point 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


  a) Light rays do not bend properly to form a single-point focus on the retina
• The index of refraction is abbreviated by the symbol:

  
  

  a) I

  
  

  b) N

  
  

  c) R

  
  

  d) V

  b) N
• 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

  c) Bent toward the normal
• Divergence occurs when light rays:

  
  

  a) Bent toward the midline

  
  

  b) Do not bend

  
  

  c) Enter "optical infinity"

  
  

  d) Bend away from the midline


  d) Bend away from the midline
• There is no refraction of light at:

  
  

  a) The optical center

  
  

  b) The index of refraction

  
  

  c) 20 feet

  
  

  d) The angle of incidence

  a) The optical center
• Light rays assume a virtually parallel course, or "optical infinity," at approximately:

  
  

  a) 20 meters (m)

  
  

  b) 20 miles (mi)

  
  

  c) 20 centimeters (cm)

  
  

  d) 20 feet (ft)

  d) 20 feet (ft)
• Convex lenses are also referred to as:

  
  

  a) Plano lenses

  
  

  b) Plus lenses

  
  

  c) Minus lenses

  
  

  d) Astigmatism lenses


  b) Plus lenses
• A lens in which the center is thinner than its edges is known as:

  
  

  a) Concave

  
  

  b) Compound

  
  

  c) Convex

  
  

  d) Plano

  a) Concave
• Light rays entering the eye must first pass through the:

  
  

  a) Retina

  
  

  b) Limbus

  
  

  c) Crystalline lens

  
  

  d) Cornea

  d) Cornea
• Which structure contributes approximately 70% of the optical power of the eye?

  
  

  a) Crystalline lens

  
  

  b) Retina

  
  

  c) Posterior pole

  
  

  d) Cornea

  d) Cornea
• 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

  d) 42.00 D
• Which part of the eye is biconvex, normally transparent, and fits just behind the iris?

  
  

  a) Retina

  
  

  b) Cornea

  
  

  c) Crystalline lens

  
  

  d) Sclera

  c) Crystalline lens
• Accommodation is defined as:

  
  

  a) Light rays entering the eye

  
  

  b) The act of the crystalline lens at varying distances

  
  

  c) The refracting power of the cornea

  
  

  d) A reduction of visual acuity with no apparent cause

  b) The act of the crystalline lens at varying distances
• 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

  a) Meters
• A 3.00 D lens has a focal length of:

  
  

  a) 3 m

  
  

  b) 0.50 m

  
  

  c) 50 cm

  
  

  d) 33 cm


  d) 33 cm
• The ability of the crystalline lens to focus is known as:

  
  

  a) Accommodative reserve

  
  

  b) Amplitude of accommodation

  
  

  c) Refractive error

  
  

  d) Accommodative insufficiency

  b) Amplitude of accommodation
• Accommodative reserve is the difference between:

  
  

  a) Supply and demand

  
  

  b) Distance and diopters

  
  

  c) Convergence and divergence

  
  

  d) Power and refraction

  a) Supply and demand
• There are approximately 130 million of which of the following in the human retina?

  
  

  a) Parallel eyes

  
  

  b) Rods

  
  

  c) Diopters

  
  

  d) Cones

  b) Rods
• Cones in the human retina provide which of the following:

  
  

  a) Peripheral vision

  
  

  b) Scotopic vision

  
  

  c) Color vision

  
  

  d) Depth perception

  c) Color vision
• 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

  d) Fovea centralis
• 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


  b) Axial length
• Axial length discrepancies will result in producing a(n):

  
  

  a) Refractive error

  
  

  b) Decrease in rods

  
  

  c) Accommodative reserve

  
  

  d) Electrophysiologic impulse

  a) Refractive error
• In an emmetropic eye, where are parallel light rays refracted?

  
  

  a) Behind the retina

  
  

  b) In front of and behind the retina

  
  

  c) On the retina

  
  

  d) In front of the retina

  c) On the retina
• Myopia is commonly called:

  
  

  a) Farsightedness

  
  

  b) Pincushion

  
  

  c) Nearsightedness

  
  

  d) Refractive index

  c) Nearsightedness
• Concave lenses would be used to correct:

  
  

  a) Emmetropia

  
  

  b) Myopia

  
  

  c) Hyperopia

  
  

  d) Presbyopia

  b) Myopia
• Minus lenses may cause:

  
  

  a) Magnified distortion

  
  

  b) Pincushion distortion

  
  

  c) No distortion

  
  

  d) Barrel distortion


  d) Barrel distortion
• 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

  c) Behind the retina
• Hyperopia is closely connected with which of the following?

  
  

  a) Astigmatism

  
  

  b) Retinoscopy

  
  

  c) Accommodation

  
  

  d) Anisometropia

  c) Accommodation
• Treatment for hyperopia is usually with which of the following?

  
  

  a) Toric lenses

  
  

  b) Convex lenses

  
  

  c) Concave lenses

  
  

  d) Complex lenses

  b) Convex lenses
• What is the distance between two lines of focus called?

  
  

  a) Interval of meridian

  
  

  b) Interval of Sturm

  
  

  c) Circle of least confusion

  
  

  d) Axial length

  b) Interval of Sturm
• 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


  b) Residual astigmatism
• In mixed astigmatism, the focal lines are:

  
  

  a) Both on the retina

  
  

  b) Both behind the retina

  
  

  c) Located one in the front of the retina and one behind the retina

  
  

  d) Located one on the retina and one in front of the retina


  c) Located one in the front of the retina and one behind the retina
• What type of lens us used for correction of compound astigmatism?

  
  

  a) Spherocylinder

  
  

  b) Concave

  
  

  c) Bifocal

  
  

  d) Convex

  a) Spherocylinder
• A normal reduction in the ability to accommodate is known as:

  
  

  a) Myopia

  
  

  b) Presbyopia

  
  

  c) Emmetropia

  
  

  d) Hyperopia

  b) Presbyopia
• What is the distinction between hyperopia and presbyopia?

  
  

  a) Accommodative reserve

  
  

  b) Axial length

  
  

  c) Accommodative amplitude

  
  

  d) Refractive error

  c) Accommodative amplitude
• Who is credited with inventing bifocals?

  
  

  a) John Adams

  
  

  b) Benjamin Franklin

  
  

  c) Alexander Graham Bell

  
  

  d) Thomas Edison

  b) Benjamin Franklin
• What is the most preventative type of cataract?

  
  

  a) Traumatic

  
  

  b) Congenital

  
  

  c) Secondary

  
  

  d) Senile


  d) Senile
• What is aphakia?

  
  

  a) The presence of refractive error

  
  

  b) The presence of a cataract

  
  

  c) The absence of the crystalline lens

  
  

  d) The absence accommodation

  c) The absence of the crystalline lens
• 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

  b) Corneal transplant