Schematic and Reduced Eyes

Question 1

. Which of the following statements is most accurate when comparing reduced eye models to schematic eye models?
A.Reduced eyes are smaller.
B.Schematic eyes have multiple refracting surfaces.
C.Schematic eyes have a uniform refractive index throughout..

Answer 1

B.Schematic eyes have multiple refracting surfaces.

Question 2

. Emsley’s reduced eye __________________

a. is hyperopic with -1D of error.
b. has a lens with uniform refractive index.
c. has relaxed and accommodated states.
d. has only one refracting surface.
e. resembles the optics of a real eye more closely than schematic eyes.

Answer 2

d. has only one refracting surface.

Question 3

In the average adult eye, the anterior nodal point N is located __________________

a. in the anterior chamber.
b. near the posterior surface of the crystalline lens.
c. near the anterior surface of the crystalline lens.

Answer 3

b. near the posterior surface of the crystalline lens.

Question 4

. In the average, unaccommodated, emmetropic adult eye, the __________________

b. the radius of curvature of anterior cornea surface is longer than the radius for the posterior corneal surface.
c. the radius of curvature of anterior lens surface is shorter than the radius for the posterior lens surface

Answer 4

b. the radius of curvature of anterior cornea surface is longer than the radius for the posterior corneal surface.

Question 5

. The posterior nodal point of the average adult eye lies

a. anterior to the front surface of the cornea.
b. within the cornea.
c. within the aqueous.
d. anterior lens.
e. anterior vitreous.

Answer 5

e. anterior vitreous.

Question 6

What is the axial length of an emmetropic eye that has a power of 65D?

a. 18.3mm
b. 19.2mm
c. 20.5mm
d. 22.9mm

Answer 6

c. 20.5mm

Question 7

The principal planes of Gullstrand’s exact eye lie

a. anterior to the front surface of the cornea
b. within the cornea
c. within the aqueous
d. within the lens
e. within the vitreous

Answer 7

within the aqueous

Question 8

What happens to the refractive power of the eye if the radius of curvature of the anterior cornea is decreased?

a. it increases
b. it decreases
c. it stays the same
d. it may increase or decrease depending on additional factors
e. it cannot be predicted

Answer 8

a. it increases

Question 9

What happens to the refractive power of the eye if the radius of curvature of the posterior cornea is decreased?

a. it increases
b. it decreases
c. it stays the same
d. it may increase or decrease depending on additional factors
e. it cannot be predicted

Answer 9

b. it decreases

Question 10

Which of the following changes will produce a decrease in the total optical power of the eye?

a. decrease the radius of curvature of the anterior cornea (will cause increase)
b. increase the radius of curvature of the posterior cornea
c. moving the crystalline lens forward toward the cornea
d. increase the refractive index of the cornea
e. decrease the refractive index of the cornea

Answer 10

d. increase the refractive index of the cornea

Question 11

. All of the following occur when the lens undergoes accommodation except which one?
A.The anterior lens surface shifts forward into the aqueous towards the cornea.
B.The posterior lens surface pushes backwards into the vitreous towards the retina
C. The lens thickness increases.
D.The nodal planes shift towards the principal planes
E. The principal planes shift towards the nodal planes

Answer 11

B. The posterior lens surface pushes backwards into the vitreous towards the retina