Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/53

Click to flip

53 Cards in this Set

  • Front
  • Back
Definition of optic center.
The point on the lens that light can pass through without bending. (no refraction/ no prismatic effect)
Point of no refraction.

Page 102
Definition of the geometric center.
The center of the eyewitness becomes the point on the datum line halfway between the two vertical and horizontal lines. Where the horizontal and vertical lines intersect.

Page 248
Definition of "A", "B", "ED", and "DBL".
A: widest horizontal measure of the box
B: widest vertical measure of the box
ED: (effective diameter) widest measurement in any direction
DBL: least distance between lenses

Page 250-251
What does prism do?
It deviates the light towards its base. It disperses the white light into component colors. It displaces the object towards its apex.

Page 101
What is the definition of a 1^ prism?
The power of a prism that can deviate the light 1 cm at the distance of 1 m.
1= 1cm/1m

Page 101
What are the canceling and adding prisms?
Canceling:
Base In and Base Out
Base Up and Base Up
Base Down and Base Down

Adding:
Base Up and Base Down
Base In and Base In
Base Out and Base Out

Page 105
What is GCD?
The distance between two geometrical centers on a frame.
A+DBL=GCD/FPD

Page 250
What is MPD?
The distance between the optical centers in a completed pair of glasses.

Page 250
The eyes ___ mm and move down ___ to read.
The eyes <3to 6> mm and move down <10 to 12> to read.
What is mechanical center?
The center of the metal block, on a blocked lens, creates a center that the edger will cut the lens around.
The average PPD for adults is ____.
The average PPD for adults is <50 to 75 mm>.

Page 239
FPD is 72. "A" measurement is 52. How much is DBL?
DBL=20mm

A+DBL=FPD
52+DBL=72
DBL=72-52
DBL=20mm
What is the MBS formula?
2xlargest decentration+ED=MBS

*MBS=minimum blank size
What are the horizontal and vertical decentration formulas?
Horizontal Decentration:
(FPD-PPD)/2
FPD>PPD = move in

Vertical Decentration:
OCHT-(B/2)
OCHT>B/2 = move up
The "A" measurement is 50, the DBL is 20, the PPD is 60 and the OCHT is 28. The frame is a round frame. How much would you decenter the lenses and what is the MBS?
5 mm in
3 mm up
60 mm MBS

FPD=A+DBL
FPD=50+20=70
(70-60)/2= 5mm in

28-(50/2)= 3 mm up

(2x5)+50= 60 mm MBS
An order form has the following information: DBL 18, B 48, ED 48, PPD 68. The lab technician forgot to take the A measurement. What would you do? How would you calculate the MBS and decentration?
1 mm out
50 mm MBS

A=B=ED in the case of a round frame.

FPD=48+18=66 mm
(66-68)/2= 1 mm out
(2x1)+48= 50 mm MBS
What is the layout blocker used for?
Blocking the lenses using the calculated decentration.

Page 255
The standard setting for an edger is ___.
The standard setting for an edger is <36.5>.
How would you write the PDPD and PNPD?
PDPD for distance and PNPD for reading.
Binocularly: # / #
First number is PDPD which is larger. Second number is PNPD which is smaller usually by 4 mm.
Monocularly: # / #
Right side is the first number and left side is the second number. Can be written this way for PDPD or PNPD.
How do you take PPD?
Sit 16 inches away from patient, line ruler with center of the patient's right pupil and left pupillary border. Read the distance.
Pupilometer or PD stick
Select decentration and the MBS for the following spectacle:
A 56, B 50, DBL 18, ED 58
PPD 68/64
3 mm in
64 mm MBS

FPD=56+18=74 mm
(74-68)/2= 3 mm in
(2x3)+58= 64 mm MBS
Select decentration and the MBS for the following spectacle:
55/20, B 52, ED 56, PPD 70/65
OCHT 28
2.5 mm in
61 mm MBS

FPD=55+20=75 mm
(75-70)/2= 2.5 mm in
28-(52/2)= 2 mm up
(2x2.5)+56= 61 mm MBS
Select decentration and the MBS for the following spectacle:
45/20, B 50, ED 51, PPD 65, OCHT 25
51 mm MBS

FPD=45+20=65 mm
(65-65)/2= 0
25-(50/2)= 0
(2x0)+51= 51 mm MBS
Select decentration and the MBS for the following spectacle:
48/18, B 50, ED 52, PPD 68
1 mm out
54 mm MBS

FPD=48+18=66 mm
(66-68)/2= 1 mm out
(2x1)+52= 54 mm MBS
Select decentration and the MBS for the following spectacle:
A 51, B 48, ED 54, DBL 19,
PPD 68/64, OCHT 20
1 mm in
4 mm down
62 mm MBS

FPD= 51+19= 70 mm
(70-68)/2= 1 mm in
20-(48/2)= 4 mm down
(2x4)+54= 62 mm MBS
Select decentration and the MBS for the following spectacle:
45/15, B 42, ED 50 PPD 58
OCHT 21
1 mm in
52 mm MBS

FPD=45+15=60 mm
(60-58)/2= 1 mm in
21-(42/2)= 0
(2x1)+50= 52 mm MBS
By using the prism formula,
1^=1cm / 1m, answer the following question:
1^prism will deviate the light 2cm at __m.
2cm / 1^= 2m
By using the prism formula,
1^=1cm / 1m, answer the following question:
4^prism will deviate a light 4 cm __m.
4cm / 4^= 1m
By using the prism formula,
1^=1cm / 1m, answer the following question:
__^prism will deviate a light 8cm at 0.50m.
8cm / 0.50m= 16^
By using the prism formula,
1^=1cm / 1m, answer the following question:__^prism will deviate a light 2cm at 1m.
2cm / 1m= 2^
By using the prism formula,
1^=1cm / 1m, answer the following question:
2^prism will deviate a light __cm at 2m.
2^ x 2m= 4cm
By using the prism formula,
1^=1cm / 1m, answer the following question:
3^prism will deviate a light __cm at 3m.
3^ x 3m= 9cm
By using the Prentice's Rule, answer the following question:
A 4.00 diopter lens decentered 2 mm creates __^prism.
(4x2) / 10= 0.8^
By using the Prentice's Rule, answer the following question:
A 10.00 D lens decentered 3 mm creates __^prism.
(10x3) / 10= 3^
By using the Prentice's Rule, answer the following question:
Looking 8mm below the optical center of a -6.00 D lens will create __^ base __.
(6x8) / 10 = 4.8^
Base Down
By using the Prentice's Rule, answer the following question:
Looking 10mm below the optical center a +4.00 D lens will create __^ prism base ___.
(4x10) / 10= 4^
Base up
By using the Prentice's Rule, answer the following question:
Looking 8mm above the optical center of a +10.00 D lens will induce __^ prism base___.
(8x10) / 10= 8^
Base down
By using the Prentice's Rule, answer the following question:
Looking 5mm above optical center of a -8.00 D lens will induce __^prism base ___.
(8x5) / 10 = 4^
Base up
Transpose the following lens:
-4.00+1.00x098
-3.00-1.00x008
Write the RX in plus form:
-2.00@140 -1.00@050
-2.00+1.00x140
Write the RX of this lens:
(+4.00) (plano) 90
+4.00-4.00x090
What are the true powers if this lens:
-5.50+2.50x055
-5.50@055 -3.00@145
What is the power at the axis of this lens:
-1.00-2.00x145
-1.00@145
What is the power at the horizontal meridian of this lens:
+1.00-0.50x090
+0.50@180
What is the power at the vertical meridian of this lens:
-2.00-3.00x180
-5.00@090
If the true powers of a lens at 180 is -5.00, and the other power is -2.00, what is the Rx of this lens?
-5.00+3.00x180
The sphere lines of the lensometer reads -1.00, the cylinder lines read +1.00, and the axis drum is on 90. What is the Rx of this lens?
-1.00+2.00x090
Sphere lines of a lensometer is focused on the +2.00, the cylinder lines is on +4.00, and the axis drum is on 120. Write the Rx of this lens in minus form.
+4.00-2.00x030
A patient is looking through 2BU prism in OD and 2BU prism in OS. How much is the imbalance?
0 prism imbalance
How much is the imbalance if a patient looks though 4BI and 2BI prisms?
6 prism imbalance
How much is the imbalance if a patient looks through 1BD and 2BU prisms?
3 prism imbalance
How much is the imbalance if a patient looks through 3BI and 2BO prisms?
1 prism imbalance
How much is the imbalance if a patient looks through 2BO and 2BO prisms?
4 prism imbalance