Optics and Refraction (Module 2)
Optics and Refraction Mastery Quiz
Test your knowledge of optics and refraction with our comprehensive quiz designed for students and professionals alike. With 100 carefully crafted questions, this quiz covers a wide range of essential topics in the field of ophthalmic optics.
Features:
- Multiple choice format
- Diverse range of questions
- Learn while you play!
The ability of a light wave from a laser to form interference fringes with another wave from the same beam, separated in time, is a measure of its
Temporal coherence
Spatial coherence
Polarization
Directionality
Which of the following properties of a laser is least clinically important in ophthalmic applications?
Energy level
Power level
Pulse duration
Polarity
All the following pairs are matched correctly except:
Diopter-reciprocal meter
Prism diopter-centimeters per meter
Refractive index-dimensionless
Frequency-cycles per degree
When a lens material has a higher index of refraction, all of the following are true except:
The velocity of light is increased in this material
The spectacle lens made from this material can be thinner
Its value of n in higher
It has a greater ability to refract light
The Airy disk image on the retina is larger when
The wavelength of light is shortened
The focal length of the eye is shorter
The pupil size decreases
Macular degeneration is present
Corneal haze secondary to corneal edema is primarily caused by
Reflection
Light scattering
Reflection
Diffraction
Candela is a unit of measure for which of the following?
Luminous intensity
Luminous flux
Illuminance
Luminance
All ophthalmic lasers require each of the following basic elements except:
An active medium
Energy input (pumping source)
Optical feedback
Plasma
Where does the -1D lens from an intermediate image?
At optical infinity
2 m in front of the lens
1 m in front of the lens
0.5 m in front of the lens
Describe the intermediate image
Upright, real, magnified
Upright, real, minified
Upright, virtual, magnified
Upright, virtual, minified
What is the size of the intermediate image as compared to the object?
Indeterminate
One-fourth the size
Half the size
Same size
What is the location of the final image?
1 m in front of the second lens
1 m behind the second lens
4 m behind the second lens
10 m behind the second lens
Describe the final image
Upright, real, magnified
Upright, real, minified
Inverted, real, magnified
Inverted, real, minified
What is the size of the final image as compared to the object?
Indeterminate
One-fourth the size
Half the size
Same size
An object is placed 25 cm in front of a concave spherical mirror with a radius of curvature of 1 m (see the following figure). The image is
Virtual with a transverse magnification of 1.77
Virtual with a transverse magnification of -0.56
Real with a transverse magnification of -1.77
Real with a transverse magnification of 0.56
Which of the following statements regarding dispersion and chromatic aberration is false?
In the human eye, blue rays focus in front of red rays
Blue print appears nearer than red print when both are displayed against a black background
Image sharpness is reduced by chromatic aberration in the eye of patients with achromatopsia
Retinal image quality is limited by chromatic aberration and diffraction even if all monochromatic refractive errors are eliminated by wavefront-guided LASIK
The far point of the nonaccommodated myopic eye
And the fovea are corresponding points
Is posterior to the eye, optically speaking
Is nearer to the eye than the point of focus of the fully accommodated eye
Cannot be moved by placing a lens in front of the eye
The near point of the fully accommodated hyperopic eye
Is beyond infinity, optically speaking
Is between infinity and the cornea
Is behind the eye
Cannot be determined without additional information
Which of the following is a recognized notation of visual acuity?
Snellen fraction
Minimum angle of resolution
Log MAR
All of the above
In which type of astigmatism do the focal lines straddle the retina?
Mixed astigmatism
Compound myopic astigmatism
Compound hyperopic astigmatism
Simple myopic astigmatism
The nodal point of the reduced schematic eye
Represents a point through which light rays enter or leave the eye undeviated
Is equivalent to the posterior focal point of the cornea
Allows the size of a retinal image to be calculated if the object height and object distance are known
A and C
You are about to write the postoperative spectacle prescription for a cataract surgery patient with macular degeneration. The best choice for a reading add for the patient with 20/70 best-corrected vision is
3.00 D
3.50 D
7.00 D
A 3.5 x magnifier
In bifocal design, image jump may be minimized by
Placing the optical center of the segment as close as possible to the top of the segment
Placing the top of the segment as close as possible to the distance optical center
Using a smaller bifocal segment
Using a blended bifocal segment having no visible line of separation
An angle of 45o corresponds to how many prism diopters (Δ)?
45
22.5
90
100
When bifocal lenses are prescribed for a patient with myopia
The practitioner should leave the choice of the segment type to the optician
A round-top segment is preferred because of its thin upper edge, which causes less prismatic effect
A flat-top segment is preferred because it lessens image jump
The 1-piece shape is indicated for adds greater than +2.00 D
Following are the results of a streak retinoscopy performed at a testing distance of 0.67 m on a 5-year-old with an accommodation esotropia. In the right eye, a +5 D sphere neutralizes the 180o meridian and a +3.5 D sphere neutralizes the 90o meridian. In the left eye, a +7 D sphere neutralizes the 180o meridian and a +6 D sphere neutralizes the 90o meridian. Which of the following statements is false?
The spherocylindrical notation for the full hyperopic correction can be expressed as RE: (+)3.5 – 1.5 x 180; LE: (+)5.5 -1.0 x 180
The child will have an induced 0.5Δ left hyperphoria looking 1 cm below the centers of spectacle lenses containing the full hyperopic correction +
The child will have an induced 2Δ exophoria looking 1 cm to the right of the centers of spectacle lenses containing the full hyperopic correction
If the examiner decrease the working distance to 0.5 m after neutralizing the retinoscopic reflex, “with” motion will be seen in all meridians
A 92-year-old patient with dry age-related macular degeneration (AMD) complains of deterioration vision in 1 eye. Best-corrected visual acuity 12 months earlier was 20/30. With the same spectacle correction, it is now 20/100. Attempted refinement of the manifest refraction using +/-0.25 D and +/-0/50 D spherical lenses and a +/-0.50 D Jackson cross cylinder elicits no change in the refraction. What is the next step?
Perform a darkroom pinhole test
Repeat the manifest refraction using a (+)/-0.75 D or (+)/-1.00 D change in sphere and a (+)/-0.75 D or (+)/-1.00 D Jackson cross cylinder
Perform a slit-lamp examination for cataract or other media opacity
Dilate the pupil and examine for a choroidal neovascular membrane
You fit a patient who has -3.50 D of myopia with an RGP contact lens that is flatter than K. If the patient’s average K reading is 7.80 mm and you fit a lens with a base curve of 8.00 mm, what is the shape of the tear lens?
Plano
Teardrop
Concave
Convex
For the patient in question 28, what power RGP lens should you order?
-3.50 D
-4.00 D
-2.00 D
-2.50 D
You fit a toric soft contact lens on a patient with a refractive error of -2.50 D -1.50 x 175. The trial lens centers well, but the lens mark at the 6 o’clock position appears to rest at the 4 o’clock position when the lens is placed on the patient’s eye. What power contact lens should you order?
-2.50 D -1.50 x 175
-2.50 D -1.50 x 115
-2.50 D -1.50 x 55
-2.50 D -1.00 x 175
All of the following statements regarding irregular astigmatism are true except:
Manifest refraction and automated refraction may be dissimilar if there is significant irregular astigmatism
Irregular astigmatism may cause a poor endpoint in clinical refraction
Irregular astigmatism may be induced by a decentered refractive surgical procedure, pellucid marginal degeneration, and keratoconus
Best-corrected visual acuity is usually better with spectacle s than with rigid contact lenses in the setting of significant irregular astigmatism
Compared with spectacles, contact lenses
Increase the accommodative requirements of myopic eyes
Increase the accommodative requirements of hyperopic eyes
Increase the convergence demands of hyperopic eyes
Decrease the convergence requirements of myopic eyes
Which of the following increase the risk of infection in a patient wearing extended-wear contact lenses?
Swimming with the contact lenses
Exposure to smoke
Corneal neovascularization
All of the above
The power of an intraocular lens (IOL) should be increased
As the power of the cornea increase and the axial length increase
As the power of the cornea decrease and the axial length increase
As the power of the cornea increase and the axial length decrease
As the power of the cornea decrease and the axial length decrease
Multifocal IOLs
Offer increased image clarity and contrast for both near and far viewing
Are independent of pupil size if they are well centered
Offer a trade-off between decreased image quality and increased depth of focus
Are indicated for all patients
Which of the following statements about piggyback IOLs is true?
Piggyback IOLs modify the vergence of light entering the eye after it leaves the incorrectly powered primary IOL
Piggyback IOLs can be used in a second operation only if the original IOL power was too low and additional dioptric strength is indicated
A piggyback IOL may be useful after removal of an incorrectly powered IOL
Piggyback IOLs may be less necessary as standard IOL power ranges increase
Aiming for a slight residual myopia in IOL power selection may be desirable because
Weaker lenses are thinner and are less likely to cause surgical or postoperative complications due to size, disruption of tissues, inflammation, and so on
The A constant is calculated for a slight degree of residual myopia
Residual myopia is closer to emmetropia than residual hyperopia
An error in power calculation is less likely to produce a resultant hyperopia, which would result in blurry vision at all distance
A patient comes for refractive surgery with keratometry readings of 43.0 D/42.0 D and a manifest refraction of -9.5D. If LASIK were performed, you would expect the postoperative average keratometry reading to be
34.9 D
36.3 D
37.3 D
34.0 D
The principle of the astronomical telescope is used for magnification in which of the following ophthalmic instruments?
Indirect ophthalmoscope
Direct ophthalmoscope
Retinal fundus camera
A and C
When a binocular indirect ophthalmoscope is used on a patient with small pupils, binocular visualization can be improved by
Moving the ophthalmoscope’s mirror closer to the observer
Narrowing the observer’s effective interpupillary distance
Moving the ophthalmoscope’s eyepieces farther apart
All of the above
Which of the following is not true of how keratometer works?
They measure the radius of curvature of the central cornea
They assume the cornea to be a convex mirror
They directly measure the refractive power of the cornea
They use a mathematical formula to convert radius of curvature to approximate refractive power
Which of the following is not a optical component of the slit-lamp biomicroscope?
Field lens
Astronomical telescope
Inverting prism
Galilean telescope
Which of the following is not a component of a optical coherence tomography (OCT) system?
Movable mirror
Beam splitter
Reference beam
Split prism
Proper distance visual acuity testing for a low vision patient includes all of the following except:
A testing chart with an equal number of symbols on each line
Nonstandardized room illumination
A Snellen visual acuity chart at 20 ft
A test distance of 10 ft
A patient with moderately low vision (20/160 in each eye) wants a prescription to be able to read; the best choice would be a(n)
(+)8.00 D single-vision reading spectacle
(+)4.00 D half-glass reader with a total of 6Δ BI prism
(+)8.00 D half-glass reader with a total of 10Δ BI prism
(+)8.00 D half-glass reader with 10Δ BI prism per lens
Which of the following statements regarding a patient with a central scotoma is false?
Most patients will fixate using an eccentric retinal location, the preferred retinal locus
The location, shape, and number of scotomata variably affect visual function
Eccentric fixation and PRL training can sometimes help patients improve coordination, tracking, and scanning and thereby facilitate function
Reading is usually not possible because central macular function is required to read
Which of the following statements regarding the prescription of visual aids is false?
The Kestenbaum rule provides a starting point to determine the appropriate addition required to read 1-M size print
Base-in prisms increase effective magnification for binocular patients using reading spectacles
Illuminated stand magnifiers help overcome stability and lighting problems associated with higher-power magnification
Optical magnification without contrast enhancement may be insufficient for patients with severely reduced contrast sensitivity function
Which of the following best characterizes a person with “low vision”?
A bitemporal hemianopsia
Best-corrected visual acuity of 20/70 or worse
Myopia greater than -20 D
A disability related to visual dysfunction
All of the following typically cause peripheral visual field deficits except:
Retinitis pigmentosa
Age-related macular degeneration
Retinal detachment
Panretinal photocoagulation
All of the following conditions commonly cause glare except:
Iritis
Corneal scarring
Posterior subcapsular cataract
Albinism
Transposition: Identify the incorrect answer:
(+) 1.00 / + 3.00 x 90= + 4.00 / - 3.00 x 180
(+) 5.00 / - 1.00 x 75= + 4.00 / + 1.00 x 165
6.00 / + 2.50 x 125= - 3.50 / -2.50 x 35
3.00 / - 1.25 x 180(=) - 4.25 / + 1.25 x 180
Using Spherical Equivalent: Identify the incorrect answer
(+) 5.00 / -1.00 x 75`= + 4.50
6.00 / + 2.50 x 125= - 4.75
3.00 / - 1.25 x 20 = + 1.75
(+) 2.00 / - 4.00 x 180
Which one of the following represent a Jackson cross cylinder?
(+)1.50 D -4.00 D × 180o
(+)0.50 D -2.00 D × 180o
(+)1.00 D -2.00 D × 180o
(+)4.00 D -4.00 D × 180o
A child has a cycloplegic refraction OD +6.00 D, OS +2.00 D. What is the best way to manage the anisometropia?
Full correction
Partial correction
Pleoptic therapy
Occlusion therapy
The average posterior chamber intraocular lens power in an adult is
35D
30D
25D
20D
A patient’s refractive error is -2.00 D -1.00 D x 180o How should we classify the refractive error of this patient?
Simple myopic astigmatism, with-the-rule
Simple myopic astigmatism, against-the-rule
Compound myopic astigmatism, with-the-rule
Compound myopic astigmatism, against-the-rule
An emmetropic patient who loss central vision came to see you which his VA was 20/100 in both eyes. According to Kestenbaum’s rule, what is the proper reading add power for this patient to read 1.0 M type (20/50)?
5 D
6 D
7 D
8 D
An object is 40 cm in front of a refracting surface of power +10.00 D. Which is the following is incorrect?
The object vergence is – 2.50 D
The image is 13.3 cm to the right of the lens
The image is real
The image vergence is – 7.50 D
A prism diopter is:
The power needed to regard an image at infinity
The apparent displacement of a ray (in meters) at 1 cm
The apparent displacement of the image (in meters) at 1 m
The apparent displacement of a ray (in centimeters) at 1 m
Multifocal IOLs: choose the correct answer
Offer increased image clarity and contrast for both near and far viewing
Are independent of pupil size if they are well centered
Offer a trade-off between decreased image quality and increased depth of focus
Are indicated for all patients
In myopic patient: Identify one correct answer
Axial length is shorter than normal
Cornea is flatter than normal
Corrected by concave lens
Distant objects are clear than near objects
In hyperopic patient: Identify one correct answer
Axial length is shorter than normal
Cornea is steeper than normal
Corrected by minus lens
Both distant and near object are clear
You perform subjective refraction in a patient with corneal scarring post car accident. When using a vertical stenopeic slit, the patient requires a +2.00 D sphere to see clearly. Using the slit horizontally, a -3.00D sphere is required. What is the appropriate spherocylinder correction?
-3.00 D +5.00 D x 90
-3.00 D -5.00 D x 90
(+)2.00 D -3.00 D x180
(+)2.00 D -5.00 D x 180
An aphakic patient wears +14.00 D glasses at a vertex distance of 12 mm. He needs hydrogel contact lens for cosmetic reason. What is the appropriate power of the contact lens you should prescribed?
(+)12.50 D
(+)14.00 D
(+)15.50 D
(+)17.00 D
In myopia
Length of eye ball is short
Corneal radius of curvature is less
Lens is less spherical
Image forms in front of the retina when the patient accommodates
What is presbyopia (old-age vision) due to?
The loss of elasticity of the lens of the eye
The change in the curvature of the cornea
The gradual loss of cone cells from the retina
the deviation from a spherical eye-ball shape with aging.
The process of adjusting the eye's lens to view objects at different distances from the eye is called:
Accommodation.
presbyopia.
refraction.
hyperopia
Accommodation refers to the eye's ability to focus light from objects whatever their distance from the eye. How is this achieved?
By altering the distance between the cornea and the eye's lens
by altering the distance between the lens and the retina
by altering the shape of the eye's lens
by altering the shape of the cornea
According to WHO a person is blind when
Vision in better eye is less than 2/60 and/or visual field is less than 30 degrees in better eye
Vision in better eye is less than 3/60 and/or visual field is less than 30 degrees in better eye
Vision in better eye is less than 3/60 and/or visual field is less than 20 degrees in better eye
Vision in better eye is less than 3/60 and/or visual field is less than 60 degrees in better eye
The following are true about the cylindrical lens except:
It has two meridian of curvature
It has no power along its axis
It can be used to measure phoria
It causes meridian magnification or minification at 900 to its axis
The onset of presbyopia depends on except:
The size of the pupil
Task required
Sex of the patients
The refractive state of the patients
Accommodation refers to the eye's ability to focus light from objects whatever their distance from the eye. How is this achieved?
By altering the distance between the cornea and the eye's lens
By altering the distance between the lens and the retina
by altering the shape of the eye's lens
by altering the shape of the cornea
The Jacson cross cylinder, is extremely used in:
To prescribe the combined cylinder forms
To transpose the minus or plus cylinder forms
To refine of the cylinder power and axis in any patients capable of subjective refraction
To find out With-the-rule or Against-the- rule astigmatism
The interpupillary distance: EXCEPT
Can be measured using the corneal reflex
Can be measured by noting the distance between the nasal limbus of one eye and the temporal limbus of the other
Used in making spectacle is 1 mm less than the anatomical interpupillar distance
For a patient with accommodative esotropia is the distance between the two corneal reflexes without spectacle correction
Complete the sentence: When prescribing bifocal lenses for a myope
The practitioner should leave the choice of the segment type to the optician.
A round-top segment is preferred because of its thin upper edge, which causes less prismatic effect.
A flat-top segment is preferred because it lessens image jump
The one-piece shape is indicated for adds greater than +2.00 D.
Which one of the followings is true about stereopsis?
Stereopsis is a function of retinal image similarity between two eyes
Stereopsis is synonymous with “depth perception”
Stereopsis appears to be most impressive between 8 and 10 months of age
Absence of stereopsis does not necessarily imply poor VA
You perform subjective refraction in a patient with corneal scarring post car accident. When using a vertical stenopeic slit, the patient requires a +2.00 D sphere to see clearly. Using the slit horizontally, a -3.00D sphere is required. What is the appropriate spherocylinder correction?
(+)3.00 D +5.00 D x 90
-3.00 D -5.00 D x 90
(+)2.00 D -3.00 D x180
(+)2.00 D -5.00 D x 180
An aphakic patient wears +14.00 D glasses at a vertex distance of 12 mm. He needs hydrogel contact lens for cosmetic reason. What is the appropriate power of the contact lens you should prescribed?
(+)12.50 D
(+)14.00 D
(+)15.50 D
(+)17.00 D
A person’s refractive error is as following. OD -1.00 D +1.00 D x 90, OS -1.00 D -0.50 D x 90
Simple myopic astigmatism both eyes
Simple myopic astigmatism right eye and compound myopic astigmatism left eye
Compound myopic astigmatism both eyes
Mixed astigmatism right eye and simple myopic astigmatism left eye
During subjective refraction using a clock dial and fogging, the patient states that the line at 1 o’clock is sharpest. How would you place the cylindrical lens to correct this astigmatism?
Place a minus cylinder at 30 degree
Place a minus cylinder at 60 degree
Place a minus cylinder at 120 degree
Place a plus cylinder at 30 degree
Which of the following lenses is a cross cylinder?
-0.50 D -0.50 D x 180
-0.50 D -1.00 D x 90
-0.25 D + 0.50 D x 90
(+)0.50 D -0.50 D x 120
A 6 years old child has a cycloplegic refraction OD +6.00 D, OS +2.00 D. What is the best way to manage the anisometropia?
Full optical correction
Partial correction
Give +4.00 D both eyes and occlude left eye
Prescribe atropine eye drop and full optical correction
A low vision patient uses a +16 D stand magnifier which locates 6.25 cm from the book. What is the magnification?
2X
3X
4X
5X
The average posterior chamber intraocular lens power in an adult is
(+)17.00 D
(+)20.00 D
(+)23.00 D
(+)27.00 D
The patient’s spectacles power is -4.00 D -1.50 D x 80o Which of the following lens has the same spherical equivalent as the patient’s spectacle?
(+)4.00 D (+)1.50 D x 170o
-4.00 D
-4.00 D (+)1.50 D x 170o
-4.75 D
A Jackson’s Cross Cylinder used during refraction
Is useful to refine the power of the sphere
Determines the axis of the cylinder
Corrects power and the axis of the astigmatism
Has power of sphere double the power of the cylinder
About aniseikonia, which is correct?
Is correctable with iseikonic lenses
Means the refraction is different between the eyes
Increases light intensity
Enhances stereopsis
The following tests depend on binocular vision: EXCEPT
Maddox rod
Maddox wing
Worth's four dots test
Duochrome tests
During clinical refraction:
Accommodation results in a more myopic prescription
The visual acuity is measured binocularly for distance and near
Occlusion is recommended for patient with nystagmus to reduce the ocul movement
A high minus lens over the non-examining eye of a patient with bilateral congenital nystagmus can reduce the nystagmus
In subjective refraction: EXCEPT
The spherical power should be tested before the cylinder
The axis of the cylinder should be verified before the power
Duochrome test should be only performed when the spherical power is corrected to within 1 D of emmetropia
Maddox rod test is useful in patients with manifest squint
A limbal corneal wound extends vertically on the nasal border of the cornea of the right eye of the patient. Postop course was uneventful but refraction showed the eye needed +3.00 x 180° astigmatic correction. The astigmatism may be decreased by:
Placing additional sutures
Removing the suture at the 180° meridian
Clear lens extraction
An IOL
The refractive state of the eye may be altered by: EXCEPT
Paralysing the ciliary muscle
changing the depth of the anterior chamber
removing the vitreous
increasing the thickness of the lens
Monovision: Identify the correct answer
Refers to the use of one eye for distant vision and the other for near
Is mainly reserved for presbyopic patients
Requires one eye to be made hypermetropic and the other myopic
Reduces visual acuity
The following are contraindication to refractive surgery: EXCEPT
Age less than 21
Keratoconus
Discontinuation of gas permeable lenses wear for less than ten weeks
Tilted disc
Photorefractive keratectomy:
Uses excimer laser made up of ultraviolet radiation
Uses thermal energy for reshaping the corneal contour
Corrects myopia by flattening the central cornea
Causes more stromal scar in high myope than low myope
LASIK is superior to photorefractive keratectomy in that it : except
Is a less painful procedure
Gives a faster visual rehabilitation
Can treat a higher myopia
Has less complication
LASIK: Identify the correct answer
Is contraindicated in patients with thin cornea
Involves the use of microtome
Involves the creation of a complete circular flap
Can be repeated by lifting the flap created if further refinement is necessary
The side-effect of LASIK include: Identify the incorrect answer
Reduced corneal sensation
Inaccurate biometry if the patient requires cataract surgery in later life
Tear film abnormality
Erroneously high intraocular pressure with applanation tonometer
Radial keratotomy: Identify the incorrect answer
Is an irreversible procedure
Weakens the cornea
Is used to reduce the refractive power of the cornea
Flattens the central cornea
Radial keratotomy: Identify the incorrect answer.
Involves incisions with depth which are at least 80% of the corneal thickness
Has a greater effect the deeper the incision
Has a greater effect the longer the cut
Has a greater effect the smaller the central zone
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