78/90

Question 1

What are the advantages of 78/90?

List structures that can be viewed

Answer 1

• Non contact
• High quality stereoscopic view
• Well illuminated
• Able to view vitreous, optic nerve, macular, retina and choroid

Question 2

Describe the image using a high powered condensing lens

Answer 2

• Magnified
• Real
• Inverted
• Reversed

Question 3

Which lens would be ideal for highest magnification and detailed macular viewing?

A. 60D
B. 78D
C. 90D
D. Superfield
E. Digital Widefield

Answer 3

A. 60D

Pick the lowest dioptic power for Highest Mag. Or Highest doptic power for highest FOV

Question 4

Which lens would be ideal for small pupils and provide the widest Field of View?

A. 60D
B. 78D
C. 90D
D. Superfield
E. Digital Widefield

Answer 4

D. Superfield

Question 5

Which lens would be ideal to reduce glare and reflections and use for slit lamp photography?

A. 60D
B. 78D
C. 90D
D. Superfield
E. Digital Widefield

Answer 5

E. Digital Widefield

Question 6

Describe the differences between using a Plus versus a Minus lens.

(Field of View, Magnification, Image Position)

Answer 6

Plus: Wide Field of View, Less Magnification, Inverted Image
Minus: Smaller Field of View, Higher Magnification, Upright Image

Question 7

What are the advantages and disadvantages of the Hruby -58.6 D lens?

Answer 7

• Extends focal range of slit lamp posterior to retinal plane
• Non-contact examination of optic disc, macula, posterior pole and vitreous
  Disadvantage:
• Multiple optical interfaces induce reflections and aberrations
• Smaller Field of View

Question 8

What type of image is seen with a Hruby lens?

Real/Virtual?, Erect/Inverted?, Stereoscopic?

Answer 8

• Virtual, Erect, Stereoscopic

Question 9

What are three advantages of 78/90D?

All relate to Slit Lamp Adjustments

Answer 9

• Variable magnification
• Adjustable illumination on slit lamp
• Change filters on slit lamp

Question 10

What can be done if no red reflex occurs?

Answer 10

• Check patient fixation
• Make sure flat plane of lens is parallel to patient’s face
• Realign light and lens from outside slit lamp oculars

Question 11

What is the Magnification Factors for:

90 D
Superfield
78D
60D
Super 66D
Digital Hight Mag
Digital Wide Field

Answer 11

90 D = 1.32
Superfield = 1.3
78D = 1.08
60D = 0.87
Super 66D = 1.0
Digital Hight Mag = 0.77
Digital Wide Field = 1.39

Question 12

You measure an optic nerve head to be 1.5 mm with a 90D. What is the actual size of the optic nerve head?

(Multiply the size by the Magnication Factor)

Answer 12

= 1.5 x 1.32 = 1.98