Ophthalmic Optics Mt 2
(109).jpg "Ophthalmic Optics Mt 2 - Quiz")
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Questions and Answers
- 1.
Reflection is when light rays are redirected in a different direction, usually with a loss in amplitude
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Reflection is when light rays are redirected in a different direction, usually WITHOUT the loss of amplitude.
Refraction is the redirection of light rays due to the loss in amplitude.Rate this question:
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- 2.
What is refraction based on?
- A.
Wavelength of light
- B.
Index of the material
- C.
Frequency of light
Correct Answer
B. Index of the materialExplanation
Refraction is based on the index of the material. The index of refraction is a property of a material that determines how much the speed of light changes when it passes through that material. When light travels from one medium to another with a different index of refraction, it bends or changes direction. This bending of light is known as refraction. The amount of bending depends on the difference in the indices of refraction between the two materials. Therefore, the index of the material is the determining factor for refraction to occur.Rate this question:
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- 3.
As n _____, the speed of light _______.
- A.
Decreases, decreases
- B.
Increases, increases
- C.
Increases, decreases
Correct Answer
C. Increases, decreasesExplanation
As the value of n increases, the speed of light decreases. This is because the speed of light in a medium is inversely proportional to the refractive index (n) of that medium. When the refractive index increases, it means that the medium has a higher density, causing the speed of light to decrease. This phenomenon is known as the refraction of light.Rate this question:
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- 4.
The slower the light passes through a lens, the ____ it gets refracted.
- A.
Less
- B.
More
- C.
No change
Correct Answer
B. MoreExplanation
When light passes through a lens, it gets refracted or bent. The speed at which light travels through a medium determines the degree of refraction. The slower the light passes through a lens, the more it gets refracted. This is because the change in speed causes the light waves to change direction as they enter the lens, resulting in a greater bending effect. Therefore, the correct answer is "more".Rate this question:
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- 5.
A prism will bend light rays towards its ________.
Correct Answer
baseExplanation
A prism will bend light rays towards its base. This is because when light enters a prism, it undergoes refraction, which is the bending of light as it passes from one medium to another. The angle at which the light bends depends on the angle of incidence and the refractive index of the prism. In a prism, the base is the wider side, and it has a larger surface area for the light to interact with. As a result, the light rays are bent towards the base of the prism.Rate this question:
- 6.
A prism will shift an image towards its ______.
Correct Answer
apexExplanation
A prism will shift an image towards its apex. This is because a prism works by refracting light, causing it to change direction. When light enters a prism, it is bent towards the base of the prism. As a result, the image formed by the prism is shifted towards the apex, which is opposite to the direction of the base. Therefore, the correct answer is apex.Rate this question:
- 7.
The prism diopter is the unite for prisms and it represents:
- A.
The angle of deviation in degrees
- B.
The angle of the apical angle
- C.
The amount of image displacement
Correct Answer(s)
A. The angle of deviation in degrees
C. The amount of image displacementExplanation
The prism diopter is a unit used to measure prisms. It represents both the angle of deviation in degrees and the amount of image displacement. The angle of deviation refers to the amount of bending or deviation of light as it passes through the prism. The amount of image displacement refers to the shift in the position of an object when viewed through the prism. Therefore, the prism diopter represents both the angle of deviation and the amount of image displacement.Rate this question:
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- 8.
An angle of 1 radian results in an arc with an equal length to the _______.
Correct Answer(s)
radius of the circleExplanation
see lecture 7 pg.2Rate this question:
- 9.
1 radian =
- A.
360deg/2pi
- B.
57deg
- C.
360 deg
- D.
2 of the above
Correct Answer
D. 2 of the aboveExplanation
1 rad = 360/2pi or 57 degRate this question:
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- 10.
1 prism diopter = ______ radians
Correct Answer
1/100Explanation
The given answer is 1/100. This implies that 1 prism diopter is equal to 1/100 radians.Rate this question:
- 11.
1 prism diopter = _____ degrees
- A.
0.57
- B.
1.57
- C.
57
Correct Answer
A. 0.57Explanation
1 rad = 57 deg, 1 pd = 1/100 rad --> 1 pd = 0.57degRate this question:
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- 12.
Describe in words what a prism diopter is.
- 13.
How much power does a prism have if it is able to displace an image by 5cm at a viewing distance of 0.5m?
- A.
10 cm
- B.
100 cm
- C.
5cm
- D.
20 cem
Correct Answer
A. 10 cmExplanation
deviation/viewing distance = x/1 m (solve for x)
5cm/0.5m = x/1m
x=10 cm or 10 pdRate this question:
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- 14.
A 20 pd BU prism will displace an image by what distance at a viewing distance of 5m? In what direction will the imave be displaced?
- A.
100 cm, towards base
- B.
100 cm, towards apex
- C.
50 cm, towards base
- D.
50 cm, towards apex
Correct Answer
B. 100 cm, towards apexExplanation
x/5m = 20cm/1m
x= 100 cm
--> images are displaced toward apexRate this question:
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- 15.
A prism is able to displace an image by 4 degrees. What is the power of the prism?
Correct Answer
7 pdExplanation
4 deg = (4)(1.75pd) = 7pdRate this question:
- 16.
What is the name of an instrument that is a tower of mini-prisms that are 1mm thick.
- A.
Risley Prism
- B.
Tower Prism
- C.
Fresnel Prism
Correct Answer
C. Fresnel PrismExplanation
many prisms act as one large prismRate this question:
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- 17.
Indicate the advantages of a Fresnel Prism.
- A.
Can be attached to any current spectacle lenses
- B.
Cheap
- C.
Heavy weight and durable
- D.
Easily changeable as the pt's condition changes
Correct Answer(s)
A. Can be attached to any current spectacle lenses
B. Cheap
D. Easily changeable as the pt's condition changesExplanation
Fresnel prims are LIGHT WEIGHTRate this question:
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- 18.
Indicate the disadvantages of Fresnel Prisms
- A.
Poor optics because of multiple prisms
- B.
Heavy and at times irritating
- C.
Expensive
Correct Answer
A. Poor optics because of multiple prismsExplanation
light weight and cheapRate this question:
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- 19.
Indicate the clinical uses of prisms.
- A.
Reduce eye turns
- B.
Enhance biocularity/stereopsis
- C.
Redirect image to pt's fovea to get similar retinal images
Correct Answer(s)
A. Reduce eye turns
B. Enhance biocularity/stereopsis
C. Redirect image to pt's fovea to get similar retinal imagesExplanation
Prisms can be used clinically to reduce eye turns, enhance binocularity/stereopsis, and redirect the image to the patient's fovea to achieve similar retinal images. By reducing eye turns, prisms help correct strabismus and improve eye alignment. They also enhance binocularity and stereopsis, which are important for depth perception and visual integration. Additionally, prisms can be used to redirect the image to the patient's fovea, which can be beneficial in cases of visual field loss or macular degeneration, ensuring that the patient receives a clear and focused image.Rate this question:
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- 20.
One should orient the prism apex away from the deviating eye to place the image where the deviating eye is looking
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Orient the prism apex TOWARD the deviating eye to place the image where the deviating eye is lookingRate this question:
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- 21.
Your patient's right eye is misaligned with his left eye so that the right is higher than left. What is the direction of the prism base that you would prescibe for the right eye?
- A.
BU
- B.
BD
- C.
BI
- D.
BO
Correct Answer
B. BDExplanation
point apex toward deviating eye and base will therefore be oppositeRate this question:
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- 22.
What components are used to specify a prism?
- A.
Base direction
- B.
Power
- C.
Apex direction
Correct Answer(s)
A. Base direction
B. PowerExplanation
A prism is specified by two components: the base direction and the power. The base direction refers to the orientation of the prism's base, which can be either up, down, in, or out. The power of the prism determines the amount of deviation or bending of light that occurs when it passes through the prism. These two components together define the characteristics and functionality of a prism.Rate this question:
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- 23.
The coordinate system for prism is the same as with cylinder axis.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Similar: the zero degree marks the start from the observer's right and increases CCW
Dissimilar: a zero degree prism base orientation differs from a 180 degree prism base orientationRate this question:
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- 24.
Because the eye muscles are yoked, prism placed before one eye affects both eyes
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because the eye muscles are yoked, meaning they work together to control the movement of both eyes. When a prism is placed before one eye, it causes a shift in the visual field for that eye, which in turn affects the alignment and movement of both eyes. This is because the brain coordinates the movements of both eyes, so any change in one eye will impact the other eye as well.Rate this question:
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- 25.
The full prism power must be placed on the eye that is deviated
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The full prism power can be placed before one eye or can be divided equally or unequally between the two eyesRate this question:
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- 26.
If a patient requires 4 BO total. Indicate what possible prisms they can use.
- A.
2 BO OD, 2 BO OS
- B.
2 BO OD, 2 BI OS
- C.
1 BO OD, 3 BO OS
Correct Answer(s)
A. 2 BO OD, 2 BO OS
C. 1 BO OD, 3 BO OSExplanation
The patient can use either 2 BO OD and 2 BO OS prisms or 1 BO OD and 3 BO OS prisms.Rate this question:
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- 27.
Splitting prisms unequally can help to equalize lens thicknesses when lens powers between the 2 eyes are not equal
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Splitting prisms unequally can help to equalize lens thicknesses when lens powers between the 2 eyes are not equal. This is because prisms can be used to correct for differences in the refractive power of the eyes. By splitting the prisms unequally, the thicker lens can be placed in front of the eye with the lower power, helping to equalize the thicknesses of the lenses. This can improve visual acuity and comfort for individuals with unequal lens powers in their eyes. Therefore, the statement is true.Rate this question:
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- 28.
With horizontal prisms, similar bases are _______. With vertical prisms, similar bases are ________.
- A.
Added, added
- B.
Subtracted, added
- C.
Added, subtracted
Correct Answer
C. Added, subtractedExplanation
With horizontal prisms, similar bases are added because the bases are aligned horizontally and when they are combined, their areas are added together. On the other hand, with vertical prisms, similar bases are subtracted because the bases are aligned vertically and when they are combined, the area of the top base is subtracted from the area of the bottom base.Rate this question:
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- 29.
A patient is prescribed horizontal prisms. She is wearing 2 pd BO OD and 2 pd BO OS. what is the total prismatic effect?
Correct Answer
5 BOExplanation
The patient is prescribed horizontal prisms with a base out (BO) direction. She is wearing 2 pd BO in the right eye (OD) and 2 pd BO in the left eye (OS). The total prismatic effect is calculated by adding the prismatic powers of both eyes together. Therefore, the total prismatic effect is 2 pd BO + 2 pd BO = 4 pd BO.Rate this question:
- 30.
A patient is prescribed horizontal prisms. She is wearing 2 pd BI OD and 3 pd BO OS. what is the total prismatic effect?
Correct Answer
1 BOExplanation
The patient is prescribed horizontal prisms, with 2 pd BI OD (base in) and 3 pd BO OS (base out). The total prismatic effect is calculated by adding the prism values together. In this case, the total prismatic effect is 1 pd BO (base out).Rate this question:
- 31.
A patient is prescribed vertical prisms. He is wearing 3 pd BU OD and 3 pd BU OS. What is the total prismatic effect?
Correct Answer
NoneExplanation
The question states that the patient is prescribed vertical prisms, but it does not mention the power or direction of the prisms. It only provides information about the patient wearing 3 pd BU OD and 3 pd BU OS, which indicates that the patient is wearing 3 prism diopters base up in both eyes. However, the question does not specify whether these prisms are vertical or horizontal prisms. Therefore, based on the given information, it is not possible to determine the total prismatic effect.Rate this question:
- 32.
A patient is presribed vertical prisms. He is wearing 2 pd BU OD and 2 pd BD OS. What is the total prismatic effect? (2 answers possible)
Correct Answer
4 BU OD
4 BD OSExplanation
The patient is prescribed vertical prisms, with 2 pd BU OD (base up in the right eye) and 2 pd BD OS (base down in the left eye). The total prismatic effect is the sum of the prism powers in each eye. Therefore, the total prismatic effect is 4 BU OD (2 pd BU OD in the right eye) and 4 BD OS (2 pd BD OS in the left eye).Rate this question:
- 33.
How does one deterine the 'reference eye'?
- A.
Eye with most power in 180 meridian
- B.
Eye with most power in 90 meridian
- C.
Eye with most spherical equivalent power
Correct Answer
B. Eye with most power in 90 meridianExplanation
The 'reference eye' can be determined by identifying the eye with the most power in the 90 meridian. This means that the eye has the highest level of refractive power in the vertical axis. The power in the 90 meridian is important in determining the astigmatism correction needed for a person's vision. By identifying the eye with the most power in this meridian, eyecare professionals can accurately prescribe the appropriate corrective lenses for the individual.Rate this question:
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- 34.
How can we ensure that there is no unwanted, induced prismatic effects?
- A.
Optical center coincides with line of sight
- B.
Optical center coincides with fovea
- C.
Optical center coincides with geometric center
Correct Answer
A. Optical center coincides with line of sightExplanation
To ensure that there are no unwanted, induced prismatic effects, it is important for the optical center to coincide with the line of sight. This means that the point where light rays converge in the lens should align with the direction in which the individual is looking. When the optical center and line of sight coincide, it helps to minimize any distortion or prismatic effects that may occur, providing a clear and accurate visual experience.Rate this question:
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- 35.
For a positive lens, it is essentialy like 2 prisms with their bases facing ____.
- A.
Outward
- B.
Inward
Correct Answer
B. InwardExplanation
see lecture 8 pg. 1Rate this question:
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- 36.
For a negative lens, it is essentially like 2 prisms with their bases facing ____.
- A.
Outward
- B.
Inward
Correct Answer
A. OutwardExplanation
A negative lens is essentially like two prisms with their bases facing outward. This means that the lens has a thinner center and thicker edges, causing light rays to diverge or spread out. When light passes through a negative lens, it bends away from the center, creating a virtual image that is smaller and upright compared to the object. The outward facing bases of the prisms in the negative lens cause the light to spread outwards, resulting in the divergence of light rays.Rate this question:
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- 37.
Prentice's Rule depends solves for:
- A.
The power of the lens
- B.
The amount of prism induced
- C.
The distance away from the OC of the lens in cm
Correct Answer
B. The amount of prism inducedExplanation
Prentice's Rule is a formula used in optometry to calculate the amount of prism induced by a lens. It states that the prism induced is equal to the power of the lens multiplied by the distance away from the optical center (OC) of the lens in centimeters. Therefore, Prentice's Rule solves for the amount of prism induced, not the power of the lens or the distance away from the OC.Rate this question:
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- 38.
The amount of prism induced requires knowledge of what factor(s)?
- A.
Power of the lens
- B.
Distance away from the OC of the lens
- C.
The refractive error of the patient
Correct Answer(s)
A. Power of the lens
B. Distance away from the OC of the lensExplanation
Prentice's Rule: induced prism = d(cm) x F
F= power of lensRate this question:
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- 39.
How much prism is induced if a +6.50 lens before the right eye is decentered 3mm nasally?
- A.
0.95 BI
- B.
1.95 BI
- C.
0.95 BO
- D.
1.95 BO
Correct Answer
B. 1.95 BIExplanation
induced prism = (0.3)(6.5)= 1.95
*because we are dealing witha (+) lens, and the OC is decentered nasally, the eye will be positioned such that there will be a BI prismRate this question:
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- 40.
A +4.00D lens is ordered for the right eye. The Rx calls for 2 BI prism before the right eye. How should the lens be decentered?
- A.
Nasally
- B.
Temporally
- C.
2 pd
- D.
4 pd
Correct Answer(s)
A. Nasally
C. 2 pdExplanation
The lens should be decentered nasally by 2 pd. This means that the lens should be shifted towards the nose by 2 prism diopters. Decentering the lens nasally helps to correct the eye's alignment and improve visual clarity.Rate this question:
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- 41.
A +3.50D lens is decentered 4 mm in and 5 mm down. What is the resultant prismatic effect?
- A.
1.4 horizontally, 1.75 vertically
- B.
1.75 horizontally, 1.4 vertically
Correct Answer
A. 1.4 horizontally, 1.75 verticallyExplanation
A +3.50D lens decentered 4 mm in and 5 mm down will result in a prismatic effect of 1.4 prism diopters horizontally and 1.75 prism diopters vertically.Rate this question:
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- 42.
If there is no prism prescribed for a patient, the PRP will be at the same location as the OC of the lens
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Prism Reference Point (PRP) is defined as the pont where the OC of the lens should beRate this question:
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- 43.
The distance between the optical center and the line of sight is the amount of:
- A.
Induced prism
- B.
Decentration
- C.
MRP
Correct Answer
B. DecentrationExplanation
this amount of decentration is then used to calculate the amount of prism induced by decentrationRate this question:
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- 44.
The major reference point (MRP) of the lens is where the prism amount is unequal to the amount that has been prescribed for the patient.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The MRP is the point on the lens where the prism amount is equal to the amount that has been prescribed for the patient.
-When there is no prism called for in the prescription, the OC and the MRP are exactly the sameRate this question:
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- 45.
What is the opticla difference between grinding in prisms and prism by decentration?
- A.
Grinding provides less aberrations
- B.
Grinding prodvides inferior optical quality
- C.
There is no optical difference
Correct Answer
C. There is no optical differenceExplanation
Both grinding in prisms and prism by decentration are methods used to correct vision problems. However, in terms of optical difference, there is no distinction between the two methods. This means that both methods can achieve similar optical outcomes and correct vision aberrations effectively.Rate this question:
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- 46.
Your optician finds that the PD and the DBOC is off by 10 mm. How much prism is induced and is it ok to dispense them?
- 47.
Your patient complains of fatigue from wearing his new glasses. The DBOC is 64mm vs 60 mm as ordered. What is the induced prismatic effect from each eye if the Rx is -2.00-100x180 OU?
- 48.
Your patient complains of vertical diplopia. Marking the glasses OCs the OD OC is 4 mm higher than the OS OC. The OS OC is centered over the pt's OS pupil. How much prism is induced and in what direction if the Rxis +4.50-200x180 OU?
- 49.
Your patient needs 2 BO OD and 1.5 BO OS. You would rather manipulate the OCs to create the prism. How much decentration is necessary and in what direction to end up with the correct prism if the Rx in both eyes is -5.00 DS?
- 50.
What is the different between compounding and cancellation?
- A.
Compounding involves subtraction and cancellation involves addition
- B.
Compounding involves addition and cancellation involves subtracion
- C.
For horizontal prisms, compounding occurs with opposite bases
- D.
For vertical prisms, cancellation occurs with similar bases
Correct Answer
B. Compounding involves addition and cancellation involves subtracionExplanation
The correct answer is that compounding involves addition and cancellation involves subtraction. Compounding refers to the process of adding two or more values together, while cancellation refers to the process of subtracting one value from another. This explanation aligns with the definitions and concepts of compounding and cancellation in mathematics.Rate this question:
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Mar 21, 2023Quiz Edited by
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Apr 26, 2011Quiz Created by
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