Retinal Image Size

Question 1

1. An object subtends a visual angle of 0.25 radians. What is the size of the retinal image formed in an uncorrected eye in which the distance between the 2nd nodal plane and retina is 20mm?
   a. 4.2mm
   b. 5.0mm
   c. 6.7mm
   d. 3.8mm
   e. 1.5mm

Answer 1

b. 5.0mm

Question 2

2. A distant object subtends a visual angle of 0.25 radians. What would be the size of the retinal image formed in an uncorrected –10 D refractive myopic eye?
   a. 5.41mm
   b. 2.17mm
   c. 4.17mm
   d. 5.00mm
   e. 4.67mm

Answer 2

c. 4.17mm

Question 3

3. The distance between the principal plane and retina is 25 mm for an axial ametrope. What would be the SM if the correction is placed at the principal plane?
   a. 1.00
   b. 1.16
   c. 0.89
   d. 1.08
   e. 1.04

Answer 3

a. 1.00

Question 4

4. A distant object that subtends a visual angle of 0.2 radians at the spectacle plane is viewed by an axial hyperope corrected with a +10.0 D lens positioned 20 mm in front of the eye’s principal plane. What would be the angle of incidence of the chief ray after refraction through the spectacle lens?
   a. 0.25 radians
   b. 0.31 radians
   c. 0.40 radians
   d. 0.17 radians
   e. 0.29 radians

Answer 4

a. 0.25 radians

Question 5

5. An axial myope is corrected with a –8.0 D lens positioned 20 mm in front of the eye’s principal plane. What is the resulting SM?
   a. 1.00
   b. 0.84
   c. 0.86
   d. 0.94

Answer 5

c. 0.86

Question 6

6. A refractive hyperope was corrected with a spectacle lens that was placed at the eye’s anterior focal point, which was 20 mm in front of the eye’s principal plane. What would be the size of the in-focus retinal image produced by distant object that subtended a visual angle of 0.3 radians?
   a. 1.6 mm
   b. 5.0 mm
   c. 4.6 mm
   d. 6.0 mm
   e. 4.5 mm

Answer 6

d. 6.0 mm

Question 7

7. For a given distant object, which of the following individuals would have the smallest retinal image (assume that the ametropias are all +5.0 D)?
   a. an emmetrope
   b. an uncorrected axial hyperope
   c. an uncorrected refractive hyperope
   d. a refractive hyperope corrected with contact lenses
   e. an axial hyperope corrected with spectacles

Answer 7

b. an uncorrected axial hyperope

Question 8

8. For a refractive hyperope with a +10D ocular refractive error _____________
   a. SM will always be greater than RSM when the eye is corrected with spectacles
   b. SM will always be less than RSM when the eye is corrected with spectacles
   c. SM will always equal RSM for both spectacle and contact lens corrections
   d. SM will always be greater than RSM when the eye is corrected with contact lenses
   e. SM will always be less than RSM when the eye is corrected with contact lenses

Answer 8

c. SM will always equal RSM for both spectacle and contact lens corrections

Question 9

9 For a given distant object, which of the following individuals would have the smallest retinal image?
A. an emmetrope
B. an axial ametrope corrected with contact lenses that produce a RSM=1.05
C. a refractive ametrope corrected with contact lenses that produce a RSM=1.05
D. a refractive ametrope corrected with spectacle lenses that produce a RSM=1.05
E. an axial ametrope corrected with spectacle lenses that produce a RSM=1.05

Answer 9

A. an emmetrope

Question 10

10. An axial hyperope is corrected with a +7.5D lens at the eye’s principal plane. What is the resulting RSM?
    a. 1.00
    b. 0.89
    c. 1.14
    d. 0.92
    e. 0.86

Answer 10

b. 0.89

Question 11

11 According to Knapp’s law, RSM=1 when ______________

a. a refractive ametrope is corrected with a lens positioned at the eye’s principal plane
b. an axial ametrope is corrected with a lens positioned at the eye’s principal plane
c. a refractive ametrope is corrected with a lens positioned at the eye’s anterior focal point
d. an axial ametrope is corrected with a lens positioned at the eye’s anterior focal point
e. any ametropic eye is corrected with a lens positioned at the eye’s anterior focal point

Answer 11

d. an axial ametrope is corrected with a lens positioned at the eye’s anterior focal point

Question 12

12. An axial hyperope with a -19D ocular refractive error is corrected with spectacle lenses positioned 10mm in front of the eye’s principal plane. What is the resulting spectacle magnification?
    a. 1.00
    b. 1.14
    c. 1.17
    d. 1.19
    e. 1.23

Answer 12

d. 1.19

Question 13

13. An axial hyperope with a -19D ocular refractive error is corrected with spectacle lenses positioned 10mm in front of the eye’s principal plane. What is the resulting relative spectacle magnification?
    a. 1.000
    b. 1.075
    c. 0.965
    d. 0.912
    e. 0.904

Answer 13

e. 0.904

Question 14

14. A refractive myope with +12.5D ocular refractive error is corrected with spectacle lenses positioned 20mm in front of the eye’s principal plane. What is the resulting relative spectacle magnification?
    a. 0.92
    b. 0.75
    c. 0.86
    d. 0.80
    e. 0.82

Answer 14

b. 0.75

Question 15

15. For a given distant object, which of the following individuals would have the smallest retinal image?
    a. an uncorrected 10D axial hyperope
    b. a 10D axial myope corrected with spectacles placed at the anterior focal point
    c. a 1 D axial hyperope corrected with spectacles placed at the anterior focal point
    d. a 10D refractive hyperope corrected with spectacles placed at the anterior focal point
    e. an emmetrope

Answer 15

a. an uncorrected 10D axial hyperope

Question 16

16. For a given distant object which of the following changes would result in an increase in image size?
    a. switching an axial hyperope from spectacles to contact lenses
    b. switching an axial myope from contact lenses to spectacles
    c. removing the spectacle lenses from an refractive hyperope so that he/she could accommodate for the distant target
    d. increasing the vertex distance of an axial myope’s spectacles from 10 to 15 mm.
    e. switching a refractive hyperope from contact lenses to spectacles

Answer 16

e. switching a refractive hyperope from contact lenses to spectacles

Question 17

17. A refractive ametrope is corrected with spectacles. The resulting SM for the right eye is 1.15; the left eye SM is 1.05. A distant object produces a retinal image that is 3 mm in size in a patient’s left eye. What would be the size of the image in the patient’s right eye?
    a. 3.00 mm
    b. 3.15 mm
    c. 3.24 mm
    d. 3.29 mm
    e. 2.74 mm

Answer 17

d. 3.29 mm