Gnioscopy

Question 1

potential errors with van hericks

Answer 1

• room illumination not reduced
• fixation may not be in primary position
• magnification too low
• wide optic section
• illumination not at 60 degrees
• not at limbus
• peripheral corneal lesions
• only if angle is open or closed

Question 2

Normal angle structure

Answer 2

• iris
• ciliary body
• scleral spur
• -trabecular mesh work
• schwalbes line

Question 3

2 methods of gonioscopy

Answer 3

• direct visualisation
• indirect visualisation

Question 4

Advantages of direct gonioscopy

Answer 4

• good magnification
• easy orientation
• can compare both eyes simultaneously
• can be used for bed bound px
• little corneal distortion
• wide field of view

Question 5

Disadvantages of direct gonioscopy

Answer 5

• time consuming
• requires large working area as px has to lie down
• may require assistant

Question 6

Advantages of indirect gonioscopy

Answer 6

• focal illumination allows location of schwalbes line
• magnified view of the angle
• excellent for fine detail
• stable image
• px sitting up

Question 7

Disadvantages of indirect gonioscopy

Answer 7

• poor lateral view
• uncomfortable
• requires coupling fluid
• observations reversed
• small field of view

Question 8

What is a G1 lens

Answer 8

• view angle by viewing in the mirror At rotating 360 degrees
• flange and non-flange available
• highest mag
• 62 degree viewing angle

Question 9

What is a G2 lens

Answer 9

• 2 mirrors at different angles
• can view angle by rotating 180 degrees
• flange and non flange available
• highest mag

Question 10

What is a G3 lens

Answer 10

• can view angle and peripheral fundus
• to view whole angle rotate 360 degrees
• flange, no flange and mini flange options
• Goldman lens

Question 11

What is a G4 lens

Answer 11

• 4 mirrors for viewing
• all mirrors at same angle
• can view whole angle by rotating 45 degrees

Question 12

Advantages of a flanged lens

Answer 12

• Easier to get an image
• more stable view

Question 13

Flange lens disadvantage

Answer 13

• needs coupling fluid
• coupling fluid can impair px ability to complete visual fields
• can’t perform indentation
• bubbles can form

Question 14

Schaffer’s grading system

Answer 14

Grade 0
- angle closed with iris-cornea contact
Grade 1
- extremely narrow
- up to trabecular mesh work
Grade 2
- angle narrow
- visible TM
Grade 3
- wide open angle
- up to scleral spur
Grade 4
- all structures visible