Optics of the Eye Quiz #1 Material (Lectures 1-9)
Which of the following is not part of the principles of keratometry? A. Measurement of the PS #I image of the mires on the cornea B. A Scheiner's disk that creates 2 clear but split images C. A doubling prism that slides along the optical axis to align the displaced images D. An internal calibration index of 1.332-1.3375 depending on the brand of keratometer E. A central corneal measurement zone of 6-8mm in diameter
E. A central corneal measurement zone of 6-8mm in diameter
The farthest away (FP) a patient can see without accommodation is 50cm while wearing a -1.00 lens. What is their refractive error? a. 2.00D Myope b. 3.00D Myope c. 1.00D Hyperope d. 1.00D Myope e. 2.00D Hyperope
b. 3.00D Myope
Using the conditions in problem 7, what is the size of the 1st PS image of the mires? a. 2.5mm b. 3.2mm c. 3.9mm d. 4.5mm e. 5.2mm
b. 3.2mm
For an axial ametrope, the distance between the nodal point and the retina is 24mm. What is the eye's ocular refractive correction (CL Rx)? a. -14.88D b. -8.88D c. -4.44D d. -12.27D e. +12.27D
a. -14.88D
You are performing distance Retinoscopy with no lenses in place. The streak is vertical and neutralized motion is seen at a distance of 50cm. Then the streak is held horizontally and neutralized motion is seen at a distance 25cm. What is the Rx? a. -2.00 - 2.00 x 180 b. +2.00 -2.00 x 090 c Plano -4.00 x 180 d. Plano -4.00 x 090 e. -2.00 + 2.00 x 90
a. -2.00 - 2.00 x 180
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
a. 0.25 radians
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
a. 1.00
A patient is wearing a +2.00 add. They have clear vision (range of clarity) as near as 33cm. What is the approximate amplitude of accommodation? (Rule of Thumb) a. 1.00D b. 1.50D c. 2.00D d. 2.50D e. 1.75D
a. 1.00D
A Patient reads at 40cm and has accommodative amplitude of +3.00 what is their total range of vision in their ideal bifocal add? a. 100cm to 25cm b. 50cm -33cm c. 60cm -25cm d. 75cm - 40cm e. 80cm - 37cm
a. 100cm to 25cm
In comparison to the real pupil, the entrance pupil is about a. 15% larger b. 5% larger c. the same size d. 5% smaller e. 15% smaller
a. 15% larger
Which of the PS images is a catoptric image? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images are catadioptric images
a. Purkinje image I
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
b. 5.0mm
An uncorrected 2D myope has a pushup amplitude ranging from a 50cm starting point, comes in to 20cm. What is this patient's amplitude of accommodation? a. 2.50D b. 3.00D c. 4.00D d. 1.00D e. 1.50D
b. 3.00D
By how much must the eyes converge to change fixation from a target at infinity to one at 1m? Assume a pupillary distance (PD) of 70mm. a. 3 pd b. 6 pd c. 7 pd d. 10 pd e. 12 pd
c. 7 pd
What is the approximate power of the posterior cornea in vivo? a. +48.8D b. +43.0D c. +6.00D d. -6.00D e. -43.0D
d. -6.00D
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
d. 1.19
A patient needs +.50 over their current distance Rx for clarity. Then they need +1.00 over their new distance Rx to see at near. What is the total lens power needed to show them their new near add over the current Rx? a. 0.50D b. 1.00D c. 1.25D d. 1.50D e. 1.75D
d. 1.50D
A patient is corrected for distance with a -10D spectacle lens positioned 25mm in front of the eye's principal plane. The patient has a 5D ocular amplitude of accommodation. What is the closest point in space that the patient can see clearly when the patient is fully accommodated? a. 20 cm in front of the spectacle plane b. 20 cm in front of the eye's principal plane c. 33.3 cm in front of the eye's principal plane d. 10.8 cm in front of the spectacle plane e. 16.8 cm in front of the spectacle plane
d. 10.8 cm in front of the spectacle plane
What is the estimated Add for a working distance of 40cm from the spectacle plane if the proximal point is located at 1m (all distances refer to the spectacle plane)? a. 0.8D b. 1.2D c. 1.6D d. 2.0D e. 2.4D
d. 2.0D
How much convergence occurs when a patient's two eyes look from a target at infinity to one at 25cm? Assume that the patient's PD is 60mm? a. 6 pd b. 12 pd c. 18 pd d. 24 pd e. 36 pd
d. 24 pd
By how much does a patient rotate one of his eyes if he reads a group of words, which is 2cm long, held at a distance of 66cm from the eyes? a. 0.75 pd b. 1.33 pd c. 2 pd d. 3 pd e. 6 pd
d. 3 pd
The average power of the total cornea for young adults is approximately A. 40D B. 43D C. 47D D. 49D E. 51D
B. 43D
Which of the following is not true about keratoscopy A. It is quick and simple to use B. It gives precise measurements of the corneal diameter C. It creates a reflection of ring shaped mires on the entire cornea D. It is used to observe corneal distortion by viewing the images of the mires E. It employs a concentric ring system called Placido's disk
B. It gives precise measurements of the corneal diameter
Keratometry is used to measure the A. Anterior corneal surface power B. The anterior corneal radius of curvature C. The posterior corneal radius of curvature D. The total corneal thickness E. The corneal diameter
B. The anterior corneal radius of curvature
Which of the following statements is most accurate when comparing reduced eye models to schematic eye models? A. Reduced eyes have multiple refracting surfaces. B. Schematic eyes have only one refracting surface. C. Reduced eyes are smaller. D. Schematic eyes have multiple refracting surfaces. E. Schematic eyes have a uniform refractive index throughout
D. Schematic eyes have multiple refracting surfaces.
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
0.904
What is the mechanism involved in the use of bifocals for slowing myopia progression?
A. It prevents over-accommodation which is believed to precede myopia progression
In general what was the purpose of using eye drops to slow the progression of myopia?
A. It prevents over-accommodation which is thought to precede myopia progression
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
A. an emmetrope
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
B. The posterior lens surface pushes backwards into the vitreous towards the retina
The calibration index used by the keratometer is A. Higher than the typical corneal refractive index B. Used to calculate total refractive power of the reduced cornea C. Equal to the index of the Gullstrand #1 model aqueous D. Equal to the index of the Gullstrand #1 model vitreous E. Equal to the index of the Gullstrand #1 model cornea
B. Used to calculate total refractive power of the reduced cornea
In general what was the purpose of (CRT) corneal reshaping therapy lenses in slowing the progression of myopia?
D. It flattens the cornea which decreases the refracting power of the eye decreasing myopia progression
All of the following are true of Pachymetry except which one? A. It is used as a preoperative test for corneal surgeries B. It measures corneal thickness C. Thick corneas may overestimate IOP however rigidity may also play a role D. Pachymetry will show lower readings in a swollen cornea E. Thin corneas with high IOP readings may be at most risk for glaucoma
D. Pachymetry will show lower readings in a swollen cornea
The far point for a patient looking through a +4.00 lens is 33cm, what is this patient's refractive correction? a. +1.00D b. 2.00D c. 3.00D d. 4.00D e. 5.00D
a. +1.00D
When measuring the angle lambda on a patient's right eye using Javal's method, you find that the pupillary axis is to the patient's right of the line of sight in object space by about 3cm at a distance of 50cm from the eyes. The angle lambda is a. +6 pd b. +3 pd c. 0 pd d. -3 pd e. -6 pd
a. +6 pd
An uncorrected emmetrope is asked to focus on an object 40cm in front of the plane of the phoropter. The phoropter, is 20mm in front of the eye's principal plane and there is no lens in the phoropter. How much spectacle accommodation is required to focus on the near object? a. 2.50D b. 3.75D c. 4.00D d. 5.00D e. 7.50D
a. 2.50D
What would be the distance between the principal plane and retina for a 9D axial myope? a. 26.14mm b. 22.22mm c. 19.32mm d. 25.55mm e. 28.01mm
a. 26.14mm
A patient's proximal point is at a distance of 80cm, and his Add was estimated to be 2.00 D. What working distance was considered? Distances refer to the spectacle plane. a. 38cm b. 52cm c. 58cm d. 69cm e. 78cm
a. 38cm
A Bichrome (Red Green) test is performed on a fully corrected patient while fogged, what do they report? a. Letters on the Red half of the eye chart appear clearer b. Letters on the Green half of the eye chart appear clearer c. Both letters on the red and green halves appear equally clear since fully corrected d. Both letters on the red and green halves appear equally blurry since fully corrected and fogged
a. Letters on the Red half of the eye chart appear clearer
A Bichrome (Red Green) test is performed on an uncorrected myope what do they report? a. Letters on the Red half of the eye chart appear clearer b. Letters on the Green half of the eye chart appear clearer c. Both letters on the red and green halves appear equally clear since fully corrected d. Both letters on the red and green halves appear equally blurry since fully corrected and fogged
a. Letters on the Red half of the eye chart appear clearer
Which PS image is the brightest? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None. all PS images are equally bright
a. Purkinje image I
Which of the following individuals would have to exert the greatest amount of ocular accommodation to focus from infinity to a point 20 cm in front of the spectacle plane? Assume that the spectacle plane is 20 mm in front of the eye's principal plane. a. a 5D axial hyperope corrected with spectacles b. a 5D axial hyperope corrected with contact lenses c. a 5D refractive hyperope corrected with contact lenses d. an emmetrope e. a 5D axial myope corrected with spectacle lenses.
a. a 5D axial hyperope corrected with spectacles
All of the following increase in an ageing lens except which one? a. amplitude of accommodation b. optical density c. opacity value d. thickness e. absorption
a. amplitude of accommodation
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
a. an uncorrected 10D axial hyperope
Purkinje image III is formed by reflection at the __________ a. anterior lens surface and is virtual and erect. b. posterior lens surface and is real and inverted. c. anterior lens surface and is real and inverted. d. anterior lens surface and located near the eye's principal plane. e. anterior lens surface and in the unaccommodated eye is the smallest Purkinje image.
a. anterior lens surface and is virtual and erect.
Assume the cornea has a power of 43D, the lens is 19D, the anterior chamber depth is 4.0mm, the aqueous is n=1.336. If the anterior chamber depth decreases by 1mm what happens to the equivalent power of the eye? a. increases by 0.62D b. decreases by 0.62D c. increases by 2.8D d. decreases by 2.8D e. no change occurs
a. increases by 0.62D
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
a. it increases
If, from the doctors perspective, the light source is moved to the left, the 1st PS image in the patient's left eye should move_________ a. nasally. b. temporally c. up d. down e. not at all.
a. nasally.
For valid keratometric readings, the cornea must be spherical (or sphero-cylindrical) over a region of diameter of about a. 1 mm. b. 3 mm. c. 5 mm. d. 7 mm. e. 12 mm.
b. 3 mm.
Which of the following changes does NOT occur when a young eye accommodates from distance to near? a. the depth of the anterior chamber increases b. the anterior to posterior thickness of the lens increases c. the radius of curvature of the anterior surface decreases more than the posterior surface radius. d. the radius of curvature of the lens core decreases e. the eye's principal planes move toward the retina.
a. the depth of the anterior chamber increases
The eye's near point is _________________ a. the point conjugate to the retina when the eye is uncorrected but fully accommodated. b. the point conjugate to the retina when the eye is corrected for distance and fully accommodated. c. always located between optical infinity and the eye's principal plane. d. always physically closer to the eye's principal plane than the eye's far point.
a. the point conjugate to the retina when the eye is uncorrected but fully accommodated.
You are performing distance Retinoscopy at a working distance of 50cm. No working lenses are in place, +2.50 neutralizes the 180 meridian and +3.75 neutralizes the 90 meridian, what is Rx? a. +0.50 + 1.25 x 180 b. +1.75 -1.25 x 90 c +1.75 -1.25 x 180 d. +3.75 -2.50 x 180 e. +3.75 -2.50 x 90
b. +1.75 -1.25 x 90
A refractive ametrope is corrected with a -2.00 -4.00 x 90 contact lens. Assuming that the contact lens is positioned at the eye's principal plane, how much ocular accommodation is required by the vertical meridian of the eye to focus on an object 40 cm in front of the eye's principal plane? a. +1.0 D b. +2.5 D c. -1.5 D d. +0.5 D e. cannot be determined without knowing the amount of spectacle accommodation.
b. +2.5 D
The anterior (primary) focal length of a refractive ametropic eye is -14mm. What is the eye's ocular refractive correction (CL Rx)? a. -35.23 D b. -11.43 D c. -22.68 D d. -7.39 D e. -9.77 D
b. -11.43 D
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
b. 0.75
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
b. 0.89
A Patient reads at 40cm and has accommodative amplitude of +3.00 what add power is indicated? a. 0.80D b. 1.00D c. 1.25D d. 1.75D e. 2.00D
b. 1.00D
A patient is corrected for infinity with a +12.50D spectacle lens positioned 20mm in front of the eye's principal plane and is fixating a point 20cm in front of the spectacle plane. How much of a reduction in the eye's total power has to take place for the patient to accommodate from the 20 cm location to a new object positioned 100 cm in front of the spectacle plane? a. 4.00 D b. 6.11 D c. 7.41 D d. 2.68 D e. 5.88 D
b. 6.11 D
A patient is corrected for distance with a +15D spectacle lens positioned 20 mm in front of the eye's principal plane. You perform a push-up test and determine that the patient has a spectacle amplitude of accommodation of 5D. What is the patient's true amplitude of accommodation (i.e., ocular amplitude of accommodation)? a. 5.0 D b. 8.9 D c. 4.5 D d. 12.5 D e. 7.3 D
b. 8.9 D
A Bichrome (Red Green) test is performed on a fully corrected patient while over minused what do they report? a. Letters on the Red half of the eye chart appear clearer b. Letters on the Green half of the eye chart appear clearer c. Both letters on the red and green halves appear equally clear since fully corrected d. Both letters on the red and green halves appear equally blurry since fully corrected and fogged
b. Letters on the Green half of the eye chart appear clearer
A Bichrome (Red Green) test is performed on an uncorrected hyperope with (ageing accommodation) what do they report? a. Letters on the Red half of the eye chart appear clearer b. Letters on the Green half of the eye chart appear clearer c. Both letters on the red and green halves appear equally clear since fully corrected d. Both letters on the red and green halves appear equally blurry since fully corrected and fogged
b. Letters on the Green half of the eye chart appear clearer
Which of the PS images is most difficult to observe? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images are virtual
b. Purkinje image II
Which of the following does NOT happen during accommodation a. The anterior surface of the lens moves towards the cornea. b. The principal planes move towards the cornea. c. The posterior surface of the lens moves away from the cornea d. The radius of curvature of anterior surface of the cornea decreases e. The dioptric power of the lens increases.
b. The principal planes move towards the cornea.
Which of the following changes in isolation would cause an emmetropic eye to become myopic? a. an increase in the refractive index of the vitreous b. a decrease in the depth of the anterior chamber c. an increase in the radius of curvature of the anterior corneal surface d. a decrease in the refractive index of the aqueous humor e. an increase in the refractive index of the cornea.
b. a decrease in the depth of the anterior chamber
The first Purkinje image produced in an unaccommodated eye viewing a distant object is_____ a. a real, inverted image located near the posterior surface of the lens. b. a virtual, erect image located near the anterior surface of the lens. c. a virtual, inverted image located in the vitreous chamber. d. a virtual, erect image that is larger than all the other Purkinje images. e. a real, erect image formed at the eye's secondary focal point.
b. a virtual, erect image located near the anterior surface of the lens.
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
b. an uncorrected axial hyperope
An object for an optical system such as a camera can best form a clear and distinct real image when it_________ a. is a good specular reflector of light. b. is a good diffuse reflector of light. c. does not reflect light. d. obeys Fresnel's equation. e. is imaged through a negative lens.
b. is a good diffuse reflector of light.
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
b. it decreases
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. d. near the cornea. e. near the retina.
b. near the posterior surface of the crystalline lens.
Which axes are used in the definition of the angle lambda? a. optical axis and visual axis b. pupillary axis and line of sight c. visual axis and papillary axis d. fixation axis and optical axis e. line of sight and optical axis
b. pupillary axis and line of sight
Suppose I placed a pen light well above my head while looking for the 4th PS image in a patient's eye. I would expect to see the 4th PS image in______________ a. the superior quadrant (above the center) of the pupil b. the inferior quadrant (below the center) of the pupil c. near the center of the pupil displaced slightly to the nasal side d. near the center of the pupil displaced slightly to the temporal side.
b. the inferior quadrant (below the center) of the pupil
An Add was estimated to be 2D for a working distance of 35cm, how far from the spectacle plane is the patient's proximal point? a. 48cm b. 52cm c. 58cm d. 69cm e. 78cm
c. 58cm
In the average, unaccommodated, emmetropic adult eye, the __________________ a. anterior focal length is longer than the posterior focal length 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 d. the anterior principal plane is closer to the retina than the posterior principal plane e. the refractive index of the vitreous is greater than the refractive index of the aqueous.
b. the radius of curvature of anterior cornea surface is longer than the radius for the posterior corneal surface.
Which of the following axes is used in the definition of the angle kappa but not in the definition of lambda? a. pupillary axis b. visual axis c. line of sight d. fixation axis e. optical axis
b. visual axis
An uncorrected 2.00D hyperope has 3.00D of accommodation. Her working distance is 33cm. What Rx will suit her best? a. +2.00 // +1.00Dadd b. +2.00 // +1.25Dadd c. +2.00 // +1.50Dadd d. +2.00 // + 2.00Dadd e. +2.00 // +3.00D add
c. +2.00 // +1.50Dadd
The secondary focal length of a refractive ametrope is 21 mm. What is the eye's ocular refractive error? a. +6.34 D b. +12.38 D c. +3.49 D d. +2.59 D e. +1.98 D
c. +3.49 D
If the actual depth of the anterior chamber were 5mm, how many mm behind the front surface of the cornea (in the eye) would the entrance pupil appear to be located? Use total cornea power and the parameters of Gullstrand's exact eye to calculate mathematically. a. -3.5 mm b. -4.0 mm c. -4.5 mm d. - 5.5 mm e. -6.0 mm
c. -4.5 mm
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 e. 0.77
c. 0.86
What is the estimated Add for a working distance of 40cm from the spectacle plane if the proximal point is located at 50cm (all distances refer to the spectacle plane using spectacle accommodation)? a. 0.80D b. 1.25D c. 1.50D d. 2.00D e. 2.40D
c. 1.50D
You are performing near retinoscopy and the patient is looking at your scope 40cm away. You use +0.75 to neutralize the motion. How much is the patient accommodating? a. 2.50D b. 3.00D c. 1.75D d. 1.00D e. 1.50D
c. 1.75D
A patient is corrected for infinity with a -12.50D spectacle lens positioned 20mm in front of the eye's principal plane. The patient has a 5D ocular amplitude of accommodation. What is the closest point in space that the patient can see clearly when he is fully accommodated? a. 6.7cm in front of the spectacle plane b. 4.7cm in front of the spectacle plane c. 11.2cm in front of the spectacle plane d. 18.0cm in front of the spectacle plane e. 14.6cm in front of the spectacle plane
c. 11.2cm in front of the spectacle plane
What would be the distance between the principal plane and retina for a 9D axial hyperope? a. 26.14mm b. 22.22mm c. 19.32mm d. 25.55mm e. 28.01mm
c. 19.32mm
A small beam of light intersects the cornea in a perpendicular manner. Approximately how much of the incident light will be reflected to form the corneal reflex? a. 0.5 % b. 1.0 % c. 2.5% d. 4.0% e. 8.0%
c. 2.5%
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 e. 24.2mm
c. 20.5mm
A patient, with a 60mm pupillary distance (PD), looks from a target at infinity to one which is 2m away. By how much will both eyes converge? a. 1.5 pd b. 2.0 pd c. 3.0 pd d. 4.0 pd e. 6.0 pd
c. 3.0 pd
A corrected patient is wearing a +1.50 add. They have clear vision to 20cm. What is the approximate amplitude of accommodation? a. 2.50D b. 3.00D c. 3.50D d. 4.00D e. 4.50D
c. 3.50D
The size of a light source is 10cm, and is positioned 12cm from the corneal apex. If the radius of curvature of the cornea is 8mm, where is the 1st PS image of the light source? a. 2.5mm behind the cornea. b. 3.2mm behind the cornea. c. 3.9mm behind the cornea. d. 4.5mm behind the cornea. e. 5.2mm behind the cornea.
c. 3.9mm behind the cornea.
If a luminous object is 5 meters in front of an eye, where is the 1st PS image located? Assume that the anterior corneal radius of curvature is 6mm and the corneal index of refraction is 1.376. a. 1mm or less behind the cornea (in the eye) b. 2mm behind the cornea (in the eye) c. 3mm behind the cornea (in the eye) d. 4mm behind the cornea (in the eye) e. 5mm behind the cornea (in the eye)
c. 3mm behind the cornea (in the eye)
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
c. 4.17mm
Through what angle does an eye rotate in order to read a line of print, which is 10cm long at a distance of 2m? a. 1 pd b. 2 pd c. 5 pd d. 10 pd e. 20 pd
c. 5 pd
If you moved a biomicroscope 4.5 mm to change focus from the front surface of the cornea to the anterior surface of the lens, then the depth of the anterior chamber should be approximately a. 4.0 mm. b. 4.5 mm. c. 5.0 mm. d. 5.5 mm. e. 6.0 mm.
c. 5.0 mm.
Given the size of the mires is 5cm and the first Purkinje- Sanson image of the mires is 2.79mm. If u, the distance from the mires to the first PS#I image is 7cm what is the radius that the keratometer will read? a. 5.85mm b. 6.78mm c. 7.81mm d. 8.28mm e. 9.58mm
c. 7.81mm
Which PS image is the largest when the eye does not accommodate? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images are the same size
c. Purkinje image III
Which of the Purkinje images changes the most when the eye accommodates from distance to near? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None of the PS images changes during accommodation
c. Purkinje image III
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
c. SM will always equal RSM for both spectacle and contact lens corrections
Which layer of the cornea has the greatest thickness? a. Epithelium. b. Bowman's layer. c. Stroma. d. Endothelim e. The tear film.
c. Stroma.
Which of the following is NOT associated with the eye's entrance pupil? a. angle lambda b. line of sight c. angle alpha d. pupillary axis
c. angle alpha
Presbyopia is considered present when the spectacle amplitude of accommodation has___________ a. increased to 3D b. increased to 4D c. decreased to 3D d. decreased to 4D e. reached an acceptable level
c. decreased to 3D
For a given ametropic eye corrected with spectacles, the difference between spectacle and ocular accommodative demands ______________ a. is independent of the vertex distance of the correcting lens. b. is independent of fixation distance. c. gets smaller as fixation distance is increased and the vertex distance is decreased.
c. gets smaller as fixation distance is increased and the vertex distance is decreased.
A patient has 11 pd constant right esotropia. Assuming normal fixation status with a 0.5mm nasal corneal reflex in each eye monocularly, the Hirschberg test shows the 1st PS image in the right pupil appearing__________ a. 2 mm to the left of the center. b. 1 mm to the left of the center. c. in the center. d. 1 mm to the right of center. e. 2 mm to the right of center.
c. in the center.
The 1st PS image in Gullstrand's Exact (#1) Eye is located a. at the corneal apex b. in the anterior chamber c. in the lens d. in the vitreous but not close to the retina e. in the vitreous and close to the retina.
c. in the lens
Which of the following changes would require the patient to exert more accommodation to focus on a given near point? a. switching a myopic patient from contact lenses to spectacle lenses b. increasing the vertex distance for the spectacle lenses of a myopic patient from 10 to 20 mm c. increasing the vertex distance for the spectacle lenses of a hyperopic patient from 10 to 20 mm d. switching a hyperopic patient from spectacles to contact lenses e. giving an emmetropic patient a +2.0 D near add
c. increasing the vertex distance for the spectacle lenses of a hyperopic patient from 10 to 20 mm
When a patient accommodates which of the following changes occur? a. the lens gets thinner along it's optical axis b. the zonules increase their tension c. the cilliary muscle contracts d. the posterior lens surface bulges forward e. the lens rises upward
c. the cilliary muscle contracts
The entrance pupil of the human eye is a a. real, erect, magnified image of the pupil. b. virtual, inverted, minified image of the pupil. c. virtual, erect, magnified image of the pupil. d. virtual, inverted, magnified image of the pupil. e. real, inverted, minified image of the pupil.
c. virtual, erect, magnified image of the pupil.
Which axis connects the nodal point of the eye and the fixation point? a. optical axis b. pupillary axis c. visual axis d. fixation axis e. line of sight
c. visual axis
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
c. within the aqueous
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
d. 3.29 mm
For an object at infinity, the 1st PS image is located a. 3.8mm from the corneal apex (outside the eye). b. 4.4mm from the corneal apex (outside the eye). c. 2.9mm from the corneal apex (in the eye). d. 3.8mm from the corneal apex (in the eye). e. 4.3mm from the corneal apex (in the eye).
d. 3.8mm from the corneal apex (in the eye).
How many PS images are there? a. 1 b. 2 c. 3 d. 4 e. 5
d. 4
The nearest point (NP) a 3.00D myope can using full accommodation through an old pair of -2.00 lenses is 20cm. What is their accommodation? a. 1.00D b. 2.00D c. 3.00D d. 4.00D e. 5.00D
d. 4.00D
If a luminous object is 5 meters in front of an eye, where is the 1st PS image located? Assume that the corneal radius of curvature is 10 mm and the corneal index of refraction is 1.4. a. 1 mm or less behind the cornea (in the eye) b. 3mm behind the cornea (in the eye) c. 4mm behind the cornea (in the eye) d. 5mm behind the cornea (in the eye) e. 6mm or more behind the cornea (in the eye)
d. 5mm behind the cornea (in the eye)
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
d. 6.0 mm
If the K reading is 40D and the calibration index is 1.3375, what is the radius of curvature of the cornea? a. 6.84 mm b. 7.44 mm c. 7.84 mm d. 8.44 mm e. 9.44 mm
d. 8.44 mm
Which is the most common shape for the normal cornea? a. Aspheric with high positive asphericity values, +2.00 or more b. Aspheric with high negative asphericity values, -2.00 or more c. Aspheric with low positive asphericity values, +0.50 or more d. Aspheric with low negative asphericity values, -0.50 or less e. Spherical with an asphericity value of 0
d. Aspheric with low negative asphericity values, -0.50 or less
The pupillary axis and the line of sight intersect at the _____________ to form the angle ______________ a. Primary nodal point Kappa b. Primary nodal point Lambda c. Center of entrance pupil Kappa d. Center of entrance pupil Lambda e. Center of rotation Kappa
d. Center of entrance pupil Lambda
The anterior focal point is 15mm in front of the principal plane of a refractive ametrope's eye. What is the patient's ocular refractive error? a. Hyperope, 6.67D b. Hyperope, 7.78D c. Myope, 4.86D d. Myope, 6.67D e. Myope, 7.78D
d. Myope, 6.67D
Which PS image gives against motion when moving the light source? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images give with motion
d. Purkinje image IV
Which PS image is inverted? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images are erect
d. Purkinje image IV
Which is a real PS image? a. Purkinje image I b. Purkinje image II c. Purkinje image III d. Purkinje image IV e. None, all PS images are virtual
d. Purkinje image IV
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
d. an axial ametrope is corrected with a lens positioned at the eye's anterior focal point
Of the frequency distribution curves for individual ocular components which one is leptokurtic and highly correlated with refractive error a. power of the cornea b. depth of the anterior chamber c. power of the lens d. axial length e. size of the pupil
d. axial length
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.
d. has only one refracting surface.
Which of the following changes, alone, might in theory increase the total positive dioptric power of the eye? a. increase the size of the retina b. increase the size of the cornea c. increase the refractive index of the cornea d. increase the refractive index of the aqueous e. increase the refractive index of the vitreous
d. increase the refractive index of the aqueous
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 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
d. increase the refractive index of the cornea
Angle alpha is formed by the ____________ a. pupillary and visual axes at the center of the entrance pupil. b. pupillary axis and the line of sight at the center of the entrance pupil. c. visual axis and the line of sight at the eye's principal plane. d. visual and optical axes at the eye's anterior nodal point. e. line of sight and the optical axis at the eye's anterior nodal point.
d. visual and optical axes at the eye's anterior nodal point.
While using Javal's method, you find that the line of sight is 2cm nasal to the pupillary axis when measured at a distance of 50 cm. The angle lambda is a. -4 pd b. -2 pd c. -1 pd d. +2 pd e. +4 pd
e. +4 pd
An uncorrected myope's far point is at a distance of 33cm and he has 1.50D of accommodation. He reads well at his 33cm working distance without glasses. He finds it inconvenient to remove his glasses while he is at work during meetings. What bifocal Rx will suit him? a. -3.00 // +0.80Dadd b. -3.00 // +1.25Dadd c. -3.00 // +1.50Dadd d. -3.00 // + 2.00Dadd e. -3.00 // +2.25D add
e. -3.00 // +2.25D add
The far point of an axial ametrope is located 15cm in front of the eye's principal plane. Assume that the spectacle plane is 15mm in front of the eye's principal plane. What would be power of the spectacle lens required to correct the eye for infinity? a. -6.67D b. +6.06D c. -6.06D d. -8.53D e. -7.41D
e. -7.41D
NRA is +2.00 and PRA is -0.50 what is the ideal near Rx for this emetropic early presbyope? a. 2.50D b. 2.00D c. 1.75D d 1.50D e. 0.75D
e. 0.75D
A myopic patient has a +5D ocular refractive error. Where does a -10D lens have to be placed to create the proper distance correction? Assume that the patient does not accommodate. a. 20 mm in front of the eye's principal plane b. 40 mm in front of the eye's principal plane c. 60 mm in front of the eye's principal plane d. 80 mm in front of the eye's principal plane e. 100 mm in front of the eye's principal plane
e. 100 mm in front of the eye's principal plane
When a patient fixates with both eyes on your pen light, you notice that the 1st PS image appears to be displaced about 0.25 mm from the center of the pupil in the temporal direction in one eye? Compared to the other eye with normal status of a 0.5mm nasal corneal reflex, what is the tropia in the turned eye? Pick the closest answer. a. The answer depends on whether it is the left or the right eye b. 6pd exotropia c. 6pd esotropia d. 16pd exotropia e. 16pd esotropia
e. 16pd esotropia
Rx +0.50D with + 2.00 Add is clear for near but blurry for distance. New refraction for better distance acuity is -0.50D. What should the new add be? a. 1.00D b. 1.50D c. 2.00D d. 2.50D e. 3.00D
e. 3.00D
If the radius of the front surface of the cornea is measured and read off the keratometer, as 7.6mm what is the actual power of the front surface of the cornea? a. 52.47D b. 41.47D c. 48.87D. d. 44.40D. e. 49.47D.
e. 49.47D.
A 0.50D myopic presbyope wears single vision +1.00 readers, what is the range of clarity if they have 2.00D amplitude? a. 67-33 cm b. 50-29 cm c. 33.3-10 cm d. 50- 10 cm e. 67- 29cm
e. 67- 29cm
The nearest point (NP) an emmetropic patient can see with full accommodation through a -2.00 lens is 20cm. What is their accommodation? a. 0.00D b. 1.00D c. 3.00D d. 5.00D e. 7.00D
e. 7.00D
Which of the following does not influence the size of the ocular entrance pupil a. diameter of the real pupil b. depth of the anterior chamber c. the refractive index of the aqueous humor d. the dioptric power of the cornea e. All of the above influence the size of the ocular entrance pupil
e. All of the above influence the size of the ocular entrance pupil
Which of the following is true in reference to the crystalline lens? a. It is flatter on the posterior surface than on the anterior surface b. It has a uniform index of refraction throughout c. Its anterior radius of curvature is shorter than the posterior radius of curvature d. It is approximately 6.0 mm in thickness when it is not accommodating e. It has an average power of approximately 19-20D unaccoomodated
e. It has an average power of approximately 19-20D unaccoomodated
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.
e. anterior vitreous.
The normal gradient refractive index of the crystalline lens ___________ a. decreases the total effective power b. increases the amount of spherical aberration. c. shows that the index of refraction decreases from the surface to the center of the lens. d. shows a higher index for younger lenses than for older lenses e. indicates the rate of change of index is faster for younger patients than older patients
e. indicates the rate of change of index is faster for younger patients than older patients
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
e. switching a refractive hyperope from contact lenses to spectacles
The straight line, which connects the fixation point and the center of rotation of the eye, is called a. the optical axis. b. the pupillary axis. c. the visual axis. d. the line of sight. e. the fixation axis.
e. the fixation axis.
