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53 Cards in this Set
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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 250251 

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=7252 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:
(FPDPPD)/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 (7060)/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 (6668)/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 (7468)/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 (7570)/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 (6565)/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 (6668)/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 (7068)/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 (6058)/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 
3.001.00x008


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 
+4.004.00x090


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:
1.002.00x145 
1.00@145


What is the power at the horizontal meridian of this lens:
+1.000.50x090 
+0.50@180


What is the power at the vertical meridian of this lens:
2.003.00x180 
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.

+4.002.00x030


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
