COT Exam Practice Questions and Answers with complete
solution
1. Which type of testing determines the retinas ability to detect subtle differ-
ences in brightness or shading between targets and their backgrounds?: Con-
trast Sensitivity testing
2. Which machine uses laser lights in a pattern of stripes in which the patient
indicates the orientation of the stripes?: Laser interferometer
3. What is the benefit of using a blue stimulus on a yellow background in
automated perimetry?: Earlier detection of visual field loss
4. Which type of defects either extend from the blind spot or point toward
it?: Paracentral
5. What does the formula P=C/D represent?: This formula explains the relation-
ship between the power of a prism and the ability to bend light. P is prism diopters.
C is the displacement of the object in cm, and D is the distance between the prism
1/6
,and the virtual image in meters.
6. What is Prince's rule used to measure?: Near point of accommodation, and
bifocal and trifocal add power.
7. What is Prentice's rule?: It's a formula to calculate induced prismatic effect
caused by spectacle lenses whose optical centers have been decentered so they
are not in line with a patients visual axis (pupil center) The formula is: Induced prism
(in prism diopters) = lens power (in diopters) x optical center displacement (in cm)
8. Find the total amount of prism induced in the follow situation: Glasses RX
OD +12 sph; OS +10sph; Both optical centers are displaced 5 mm temporally
(centered out).: OD has 6 prism diopters of BO. OS has 5 prism diopters of BO.
The total is 11 prism diopters of BO.
9. What is the focal length (in meters) of a 3 diopter lens?: P=1/f(meters), 3=1/f,
3f=1f=1/3, or 33cm
10. What does Snell's law determine?: Whether the refracted ray will be bent
toward the normal or away from it.
11. List ways to clean the dust on the lenses of a manual lensmeter: 1. Blowing
2/6
, the dust off with a clean, rubber bulb syringe
2. A dust brush
3. Compressed canned air
12. Name 4 examples of lenses that contact the eye and may require disinfec-
tion or sterilization: 1. Diagnostic contact lenses.
2. Fundus contact lens
3. Gonio lens
4. Koeppe lens
13. Name 10 general types of mechanism of disease and injury: 1. Infectious
2. Inflammatory
3. Allergic
3/6
solution
1. Which type of testing determines the retinas ability to detect subtle differ-
ences in brightness or shading between targets and their backgrounds?: Con-
trast Sensitivity testing
2. Which machine uses laser lights in a pattern of stripes in which the patient
indicates the orientation of the stripes?: Laser interferometer
3. What is the benefit of using a blue stimulus on a yellow background in
automated perimetry?: Earlier detection of visual field loss
4. Which type of defects either extend from the blind spot or point toward
it?: Paracentral
5. What does the formula P=C/D represent?: This formula explains the relation-
ship between the power of a prism and the ability to bend light. P is prism diopters.
C is the displacement of the object in cm, and D is the distance between the prism
1/6
,and the virtual image in meters.
6. What is Prince's rule used to measure?: Near point of accommodation, and
bifocal and trifocal add power.
7. What is Prentice's rule?: It's a formula to calculate induced prismatic effect
caused by spectacle lenses whose optical centers have been decentered so they
are not in line with a patients visual axis (pupil center) The formula is: Induced prism
(in prism diopters) = lens power (in diopters) x optical center displacement (in cm)
8. Find the total amount of prism induced in the follow situation: Glasses RX
OD +12 sph; OS +10sph; Both optical centers are displaced 5 mm temporally
(centered out).: OD has 6 prism diopters of BO. OS has 5 prism diopters of BO.
The total is 11 prism diopters of BO.
9. What is the focal length (in meters) of a 3 diopter lens?: P=1/f(meters), 3=1/f,
3f=1f=1/3, or 33cm
10. What does Snell's law determine?: Whether the refracted ray will be bent
toward the normal or away from it.
11. List ways to clean the dust on the lenses of a manual lensmeter: 1. Blowing
2/6
, the dust off with a clean, rubber bulb syringe
2. A dust brush
3. Compressed canned air
12. Name 4 examples of lenses that contact the eye and may require disinfec-
tion or sterilization: 1. Diagnostic contact lenses.
2. Fundus contact lens
3. Gonio lens
4. Koeppe lens
13. Name 10 general types of mechanism of disease and injury: 1. Infectious
2. Inflammatory
3. Allergic
3/6
