Slit Lamp 3 GONIO - Week 4

Question 1

Name 6 methods for examining anterior chamber

Answer 1

• VH
• Iris Shadow
• Smith’s method
• Spot/cone of light, 60deg, dark room
• Gonioscopy
• OCT

Question 2

How does OCT examine anterior chamber?

Answer 2

quantify depth, and visualize structures in vivo non-invasively

e.g. iris insertion and configuration

Question 3

List the indications for performing Gonio:

Answer 3

• narrow angle (VH less than 0.3; iris shadow over 0.5)
• to assess suitability for dilation
• when you suspect glaucoma
• signs of angle-closure glaucoma
• iris neovascularisation, retinal ischaemia
• iris anomalies
• uveitis
• trauma (irididodialysis, angle recession)

Question 4

What type of iris anomalies serve as an indication to perform gonioscopy?

Answer 4

lumps, transillumination, bowing, distorted pupil etc.

Question 5

List the anatomical structures visible in gonioscopy from posterior to anterior

Answer 5

• Iris
• ciliary body
• scleral spur
• trabeculae
• schwalbe’s line
• cornea

Question 6

What anatomical structures are visible in gonioscopy when looking at grade 0 or 1 angle?

Answer 6

Iris and cornea only. Rest are hidden

Question 7

What does the scleral spur look like in gonioscopy?

Answer 7

White band

Question 8

What does ciliary body look like in gonioscopy?

Answer 8

Colour varies - light or dark brow, grey or mottle band

Question 9

What does posterior TM look like in gonioscopy?

Answer 9

pigmented

Question 10

What does anterior TM look like in gonioscopy?

Answer 10

pale

Question 11

What does schwalbe’s line look like in gonioscopy?

Answer 11

Thin grey, pearly white, or pigmented line

Question 12

When using gonioscope, what image do we see when looking into the superior mirror? inferior mirror? nasal? temporal?

Answer 12

superior mirror: lets us look at inferior angle
inferior mirror: superior angle
nasal mirror: temporal angle
temporal mirror: nasal angle

Question 13

What images appear in a 3-mirror gonio? How does this differ to a 4-mirror gonio?

Answer 13

3 mirror: one mirror = see anterior chamber, other 2 mirrors = look at various parts of retina

4 mirror: all 4 mirrors are same angle therefore all look at anterior chamber

Question 14

List advantages of 4 mirror gonio:

Answer 14

• don’t require viscous medium
• some suggest tear film adequate?
• can be static or dynamic gonio
• optional flange
• view 4 quadrants (minimal rotation required)
• easy removal (no suction)
• superior px comfort

Question 15

List disadvantages of 4-mirror gonio

Answer 15

• more difficult to master?
• stability (can be blinked off)
• view inferior to 3-mirror?
• difficult to handle?

Question 16

List advantages of 3-mirror gonio

Answer 16

• good for producing a stable, clear image
• keeps central position
• versatile

Question 17

List disadvantages of 3-mirror gonio

Answer 17

• lens must be rotated to evaluate all 360deg of angle
• beware of cushioning agent used (old ones can be toxic(
• px apprehension because of large looking lens (appears more invasive)

Question 18

List instructions for gonioscopy

Answer 18

• indicate what test involves
• why it needs to be performed
• “lens will feel a bit cold”

Question 19

Where do you instill the anaesthetic before gonioscopy?

Answer 19

conjunctival fornix

Question 20

Name 2 contraindications for anaesthetic drops

Answer 20

• allergies

- anaesthetic reaction

Question 21

Why should you advise a px to not rub eye after anaesthetic?

Answer 21

because they won’t feel it and they may rub too hard and cause damage

Question 22

What slit lamp settings should you have during gonioscopy?

Answer 22

Use a vertical PPD 2-3mm wide with magnification at 6-16x and low-medium intensity

Question 23

Why use low-medium intensity in slat lamp during gonio?

Answer 23

To avoid excessive pupil constriction

Question 24

Should you provide a fixation target during gonio?

Answer 24

yes

Question 25

How should you hold the gonio lens?

Answer 25

between thumb and 2nd finger

Question 26

How do you focus the view in gonioscopy?

Answer 26

by moving the slit lamp in and out

Question 27

What does the centre lens of the gonioscope let us see?

Answer 27

the fundus

Question 28

How do you record gonioscopy?

Answer 28

Draw an X with each quadrant representing the following angles: superior, inferior, nasal, temporal angles.

In each quadrant/angle, write the initials of the deepest structure you can see

Question 29

How does pigmentation affect the optom’s ability to make out structures in gonioscopy?

Answer 29

Less pigmented = harder

more pigmented = easier

Question 30

What if air bubble between cornea and gonio?

Answer 30

Not pressing with gonio enough. Tilt the lens towards the bubble (if bubble is large: reinsert the lens)

Question 31

What if you see corneal folds in gonio?

Answer 31

Pressing too hard. Apply less pressure

Question 32

What if patient is blinking in gonio?

Answer 32

• hold the lids

- maybe check if anaesthetic still there/working

Question 33

What if you are getting reflections in gonio?

Answer 33

change incident beam angle slightly, width, intensity, height

Question 34

What if poor view in gonio?

Answer 34

• check lens centration and illumination arm is not blocking the objective

Question 35

What if no structures visible in gonio?

Answer 35

• check centration
• try corneal wedge
• OS - is beam deflected at iris-cornea interface
• try tilting the lens
• try identation

Question 36

What if schwalbe’s line nor visible in gonio?

Answer 36

try using corneal wedge technique: reduce illumination to a narrow slit, increase intensity and off-set illmination

Question 37

List 8 contraindications for Gonioscopy

Answer 37

• Anaesthetic Reaction
• Lacerated or perforated globe (pressure will cause aqueous to drain out of the eye)
• Hyphaema (will cause a rebleed)
• Pregnancy (reduced corneal healing)
• Corneal/Conjunctival infection or epithelial basement membrane dystrophy
• Corneal epithelium already weak
• OCT