# data[].attributes.body
If light enters a convex surface from a dense to rare medium, will the power be (+), (-) or 0?
A. (+)
*B. (-)
C. 0

Dr. J comment: looks good

# data[].attributes.body
The radius of curvature of the front surface of a lens is +5 cm.  The index of the lens is 1.6.  What is the front surface power of this lens? Assume the lens is in air.
A. -12 D
B. -8.3 D
C. +12 D**
D. +8.3 D

Dr. J comment: looks good

# data[].attributes.body
A patient wearing plus lenses looks to the left, what kind of prism is the patient's right eye looking through?

a. base up
b. base down
c. base in
d. base out ***
e. the prism takes a nap

Dr. J comment: good

# data[].attributes.body
A small pinhole allows __ rays through but not __ rays.
A.  diverging; converging
B. converging; diverging
C. paraxial; peripheral *
D. peripheral; paraxial

Dr. J comment: good

# data[].attributes.body
What is the net prism for a person that wears 8 BI over each eye?
A) 16 BO
B) 8 BO
C) 8 BI
*D) 16 BI

Dr. J comment: good

# data[].attributes.body
What is the net prism power and direction with 5 base up and 4 base out over OD?

a) 6.4 @ 51.3 degrees
*b) 6.4 @ 128.7 degrees
c) 9 @ 51.3 degrees
d) 9 @ 128.7 degrees

# data[].attributes.body
If there is four prism diopter base up over the left eye and six prism diopters base down over left eye, then what is total prism diopter power and direction?
A. 2 BD*
B. 10 BD
C. 2 BU
D. 10 BU

Dr J: good

# data[].attributes.body
Patient needs 5BO and 2BU over the left eye. What is the resultant prism power?
A. 4.5
B. 6.3
C. 7.2
D. 5.4****

dr. J: also make sure you can figure out the angle

# data[].attributes.body
You have two prisms that are 15 prism diopter in the Risey. One is base 60 degrees and one is base 120 degrees. How much prism is the patient looking through.

A. 26 prism diopter BD
* B. 26 prism diopter BU
C. 15 prism diopter BU
D. 15 prism diopter BD

dr. J: *Risley

# data[].attributes.body
What classifies a lens as thick?

A. A vergence change in the lens of 0.25D or greater.*

B. Power difference between front and back surface of 0.25D or greater.

C. A lens that is at least 5mm thick.

Dr. J: good

# data[].attributes.body
which radius is longer in a concave meniscus lens?
A. Front radius *
B. Back radius
C. Same length
D. Panic

Dr. J: good

# data[].attributes.body
For a plus lens with a power of 4D, what is the furthest the object can be away from the lens while still creating an upright image?
*A. -24 cm
B. +24 cm
C. +26 cm
D. -26 cm

Dr. J comment: for a real object, the object has to be closer than -25cm. But for ANY virtual object, you would have an upright image, too.

# data[].attributes.body
For a convex meniscus lens, what part of the lens has a shorter radius of curvature?
*A) Front Surface
B)Principal Plane
C) Back Surface
D)It's the same throughout the lens

Dr. J: good

# data[].attributes.body
Team 2A
If you have a 1cm lens (n=1.5) with a front surface power of +3.00D and back surface power of +8.00D, what is the equivalent power of the lens?
A. 11.00D
B. 10.50D
C. 23.93D
D. 10.84D*

Dr. J: good

# data[].attributes.body
As light goes from a dense to a rare medium through a convex surface, what power does the surface have?
A. Plus power
B. Minus power (correct)
C. Electric power
D. Horsepower

dr. J: good

# data[].attributes.body
What would happen to a minus lens if you increase the lens thickness?

**A) less minus
B) stays the same
C) more minus
D) depends on where the object is located

Dr. J: good

# data[].attributes.body
Moving from a dense to rare medium, how does the ray bend?

*A. Away from the normal line
B. Toward the normal line
C. It doesn’t

Dr.J: good

# data[].attributes.body
How does the power of a biconcave lenschange as the Lena gets thinner?

A. Gets more plus
*B. Gets more minus
C. Stays the same
D. Induces more prism

Dr. J: good

# data[].attributes.body
A 2 cm thick lens (n=1.5) has a front surface power of +4 and a back surface power of -2 what is the equivalent power of the lens?
A. +3
B.+1.89
*C.+2.12
D. +2.53

Dr. J: good

# data[].attributes.body
Decreasing the thickness of a concave meniscus lens will make the lens:
A. More plus
*B. More minus
C. Less minus
D. No change

Dr. J: good

# data[].attributes.body
Risley prisms are adjusted with one base at 135 degrees and the other at 225 degrees over the OS. What is the resultant base direction?
A. BI**
B. BO
C. BU
D. BD

Dr. J comment: good

# data[].attributes.body
When determining the lateral magnification it a multi lens system, you divide the object vergence by the final image vergence?!
A. True
B. False
C. I give up

Dr. J: a little unclear in the stem. You could say L of lens 1 divided by L' of lens 2 to be clearer? You didn't put what you think is the answer, but it should be false.

# data[].attributes.body
What horizontal and vertical prisms combine to give 3 prism diopters at 280 degrees over the OS?

1. 0.8 BO and 3.2 BD
2. 0.53 BO and 2.95 BD*
3. 0.25 BO and 3.45 BD
4. 1.5 BO and 1.5 BD

# data[].attributes.body
when light is going into a meniscus (with + r values) going from rare to dense and exiting to an more dense material, which surface power would be more plus?

A. F1
B. F2**

Dr. J: I don't think you have enough information to answer. They would both be plus powers, but without knowing the radii or the indexes I don't see how you could pick one. Am I missing your point?

# data[].attributes.body
True or false- you can have total internal reflection from both rare to dense or dense to rare mediums.
A-true
*B-false

dr. J: good

# data[].attributes.body
What is the Fe for a lens that has a front surface power of +7D,  back surface power of -2D, thickness of 2mm and n=1.5

1) 5.01**
2)5.19
3) 4.81
4)4.98

dr. J: good, but would round to 5.02 :-) 2mm isn't especially thick either as the result would indicate

# data[].attributes.body
The front surface of a thick lens is +8 and the back surface is -1. The thickness is 5 cm and the index of the lens is 1.68. What is the equivalent power? And what lens shape is this?

A: +7.24, concave meniscus
*B: +7.24, convex meniscus
C: +6.76, convex meniscus
D: 6.76, biconvex

# data[].attributes.body
If a patient is reading a book up close through minus lenses and the optical center is in the middle of the lens, what kind of prism are they looking through?
A. OD-BO/OS-BO
B. OD-BI/OS-BI***
C. OD-BO/OD-BI
D. OD-BI/OD-BO

# data[].attributes.body
If light is entering a convex surface from a dense to rare medium, will the power be (+), (-) or 0?
A. (+)
*B. (-)
C. 0

Dr. J: good

# data[].attributes.body
Going from air, which medium would bend light closest to the normal line?
a. Water
b. Plastic
*c. Crown glass
d. air

Dr. J: There are a number of plastic materials with different indexes, so would need to specify which one. CR-39? Polycarbonate? I'll give indexes of lens materials if you need to know.

# data[].attributes.body
A lens has a front surface with a positive radius of curvature and a back surface with a negative radius of curvature.  What is the shape of this lens?

A. Biconcave
B. Biconvex *
C. Concave meniscus
D. Convex meniscus
E. Circle

# data[].attributes.body
Team 4B (GOAT)

If the parallel rays coming from the Death Star’s laser passed through a 5cm thick lens (n = 1.6) with a front surface power of +5.00 and a back surface power of +4.00, will the laser beam converge on a planet 15 cm away?

A. Annihilated
B. Not annihilated *

dr. J: seriously?
And, did you mean front and back surface powers or vertex powers? I think you mean surface powers.

# data[].attributes.body
What is the add power for a bifocal lens with the following powers:
Power through the top with back against the stop: -4
Power through the bifocal with the back against the stop: -2.50
Power through the top with the front against the stop: -5
Power through the bifocal with the front against the stop: -3

A: +1.50
B: +2.00*
C: +1.00
D: +0.50

# data[].attributes.body
Two 5 prism diopter prisms are at 40 degrees and 140 degrees over OD. What is the net prism power and base direction?

*A. 6.43 prism diopters BU
B. 5 prism diopters BD
C. 7.66  prism diopters BU
D. 2.5 prism diopters BU

# data[].attributes.body
Patient needs 4 BI and 6 BD over the OS. Resultant single prism power?
A. 6.4 prism
B. 5.8 prism
C. 7.2 prism***
D. 7.8 prism

Dr. J: good

# data[].attributes.body
If you have 4 prism diopters Base up in OD and 3 prism diopters Base down in OS, what is the net prism effect?

1. 1 prism D BU OS

2. 1 prism D BU OD

3. 7 prism D BU OD **

4. 5 prism D BO OD

# data[].attributes.body
If you have minus vergence going into a plus lens and plus vergence leaving the lens, you will have an inverted image.

*A. True
B. False

Dr.J: true, but this doesn't really hit on a 2nd midterm topic per se. You need to know this, but could tailor this more to thick lenses?

# data[].attributes.body
If you increase the thicknesses of a biconcave lens, how will the back vertex power change?

A. More negative
*B.  More plus
C. No change in power

# data[].attributes.body
What is the critical angle for glass (n=1.52) to water (n= 1.33) interchange?
A. 90 degrees
B. 52 degrees
*C. 61 degrees
D. No critical angle

Dr. J: good

# data[].attributes.body
Team 9b

True or false: The light ray is always deviated towards the apex of the prism.

False: the light is deviated toward the base, the image appears to move in the direction of the apex

Dr. J: good

# data[].attributes.body
You are a myope, gasp! While wearing your best correction glasses, you look up towards the top of your lenses. What kind of prism are you looking through?

a. Base Out
b. Base Down
c. Base Up*
d. Base In

dr. J: to be clear: an eye can BE myopic; a person can HAVE myopia

# data[].attributes.body
What is the critical angle for an interface if the incident medium has an index of 1 and the emergent medium has an index of 1.49?
A. 42.16•
B. 2.6•
*C. There is no critical angle.
D. 90•

Dr. J: good

# data[].attributes.body
Team 8A

# data[].attributes.body
Diverging light is 3meters away from a +20 lens and a -10D that are separated by 30cm. If a screen is 1 meter away will an image be formed on it?

A. Yes
B. No*

Dr. J: so where will the image be formed? What kind of image is formed?

# data[].attributes.body
If the index of the cornea is 1.376,  an effective gonioscopy lens could have an index of..
a. 1.276
b. 1.137
c. 1.255
*d.1.567

Dr. J: good one...a little bit of a thinker.

# data[].attributes.body
A patient looks through the bottom half of a minus lens. What prism is induced?
a. Base up
*b. Base down
c. Base in
d. Base out

Dr. J: good. Be sure you can calculate how much (Prentice's rule)

# data[].attributes.body
How much prism is induced when looking 4mm away from the center of a +5D lens?
a. 1PD
*b. 2PD
c. 3 PD
d. 4 PD

# data[].attributes.body
What determines cardinal points/planes?
a. Lens shape
b. Object distance
c. Index of refraction of the lens
d. Back vertex power
e. a & b
*f. a & c
g. c & d