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OD1 - Integrated Ophthalmic Sciences & Preclinical Optometry > PC - Slitlamp Biomicroscopy 3 (Gonioscopy) - Week 4 > Flashcards

PC - Slitlamp Biomicroscopy 3 (Gonioscopy) - Week 4 Flashcards

1
Q

What grades of Van Herrick should be examined with gonioscopy?

A

Grades I and II.

Grade I is a must.

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2
Q

What Van Herrick ratio is an indication for gonioscopy?

A

<0.3

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3
Q

What iris shadow is an indication for gonioscopy?

A

> 0.5

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4
Q

What 5 pathologies are an indication for gonioscopy (12)?

A
  • Iris neovascularisation
  • Retinal ischaemia
  • Iris anomalies (lumps, transillumination, bowing, distorted pupil)
  • Uveitis
  • Trauma (iridodialysis, angle recession)
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5
Q

Name the structures seen in gonioscopy in order (6).

A 
Iris
Ciliary body
Scleral spur
Trabecular meshwork
Schwalbe's line
Cornea
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6
Q

How do ciliary bodies appear in gonioscopy?

A

Colour varies, light/dark brown, grey, or mottled band

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7
Q

How does the scleral spur appear in gonioscopy?

A

White band

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8
Q

How does the posterior trabecular meshwork appear in gonioscopy?

A

Pigmented

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9
Q

How does the anterior trabecular meshwork appear in gonioscopy?

A

Pale

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10
Q

How does Schwalbe’s line appear in gonioscopy (3)?

A

Thin grey or pearly white or pigmented line.

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11
Q

Name 5 advantages of indirect gonio lens design.

A
  • Can do indentation gonioscopy
  • Evaluation of angle in sitting position
  • High magnification by SL possible
  • Laser treatment of angle
  • Fundus and gonio view with the same lens
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12
Q

Name 3 disadvantages of indirect gonio lens design.

A
  • Unintentional corneal indentation can open appositional occluded angle
  • Angle appears shallower than with a koeppe lens
  • Needs viscous coupling fluid, can reduce cornea clarity
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13
Q

Name 6 advantages of 4-mirror gonio lenses.

A
  • No viscous medium needed, some say TF is adequate
  • Static and dynamic gonio
  • Optional flange
  • Views 4 quadrants
  • Easy removal
  • Superior patient comfort
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14
Q

Name 4 disadvantages of 4-mirror gonio lenses.

A
  • More difficult to master
  • Less stability, can be blinked off
  • Inferior view compared to 3-mirror
  • Handle difficult
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15
Q

How does a 3-mirror gonio lens work?

A

Suction using a coupling fluid between the lens and the eye.

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16
Q

Name 3 advantages of using a 3-mirror gonio lens.

A
  • Good for stable and clear images
  • Keeps central position
  • Versatile, can do retinal examination at the same time as gonioscopy
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17
Q

Name 3 disadvantages of using a 3-mirror gonio lens.

A
  • Lens must be rotated to evaluate the full 360 degrees
  • Old cushioning agents can be abrasive and toxic to the cornea
  • Patient apprehension due to large lens, appears more invasive
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18
Q

Describe the patient instructions for gonioscopy (6).

A 
Indicate what the test involves
Why it needs to be performed
Lens will feel a bit cold
Will touch their eyes for a bit
May feel uncomfortable, wont hurt
May feel liquid down their cheek, is normal
19
Q

Describe 4 ways a gonio lens can be cleaned.

A
  • Lukewarm water with a disinfectant/chlorhexidine
  • Some use alcohol swabs
  • 1:10 bleach for 25 mins
  • Hydrogen peroxide, 3% for 10 mins
  • Dry with lint-free cloth
20
Q

Describe the procedure for gonioscopy (5).

A 
Apply coupling medium to the concave surface.
Instil anaesthetic to the patient's eye
-One drop initially, add as needed
-Punctal occlusion
-Advise not to rub eyes
21
Q

What are two contraindications to anaesthetic drops?

A

Allergies

Anaesthetic reaction

22
Q

How should the slit-lamp illumination be set up during gonioscopy?

A

Coaxial or slightly off-axis if needed

23
Q

What slit-lamp setup is best for gonioscopy (6)?

A

Mag at 10x, vertical, parallelepiped 2-3mm wide with the beam height encompassing the gonio lens diameter, and low/med intensity to avoid excessive pupil constriction.

24
Q

Describe how a gonio lens is placed onto an eye.

A

Three ways:
-Patient asked to look up, pull their inferior eyelid down, place the lens on their inferior conjunctiva, and have them look forward.
-Patient asked to look down, pull their superior eyelid up, place the lens on their superior conjunctiva, and have them look forward.
Release the lids only once the lens is straight and contacting the cornea.
-Use two hands to raise/lower the eyelids, then use forefinger and thumb to place the lens directly on the cornea.

25
Q

How should the gonio lens be aligned on the cornea?

A

The pupil should take up the central mirror.

26
Q

In what order should the mirrors be assessed?

A

With the widest and most pigmented:

I>T>N>S

27
Q

What should be done when viewing the lateral mirrors?

A

Beam should be rotated to horizontal

28
Q

Should the gonio lens be rotated?

A

Yes, once the first four quadrants are assessed, it should be rotated 45 degrees

29
Q

Describe the recording for gonioscopy.

A

Specify which eye, the drops used, time, amount, and no contraindications.
Draw 4 quadrants, and in each write the most anterior structure visible.

30
Q

Describe the Shaffers grading system for gonioscopy.

A 
Based on the most anteriorly visible structure:
Grade IV - ciliary body
Grade III - scleral spur
Grade II - trabecular meshwork
Grade I - shwalbe's line
Grade 0 - cornea
31
Q

Troubleshoot the following for gonioscopy:

Air bubbles

A

Gonio lens isnt flat, tilt the lens towards the bubble

If it large, reinsert the lens

32
Q

Troubleshoot the following for gonioscopy:

Corneal folds

A

Too much pressure, apply less

33
Q

Troubleshoot the following for gonioscopy:

Blinking

A

Hold the lens still, or add more anaesthetic drops

34
Q

Troubleshoot the following for gonioscopy:

Reflections

A

Change the incident beam slightly, width, intensity, height

35
Q

Troubleshoot the following for gonioscopy:

Poor/no view

A

Check lens centration and illumination arm not blocking the objective

36
Q

Troubleshoot the following for gonioscopy:

No structures visible

A

Check centration
Try corneal wedge
Tilt the lens
Try indentation

37
Q

List 4 tips when performing gonioscopy.

A

Carry out binocularly to compare
Rest elbow on a box
Pushing too hard pushes aqueous to the periphery, angle appears wider
Perform gonio in a dark room with a narrow beam

38
Q

Why should gonioscopy be performed in a dark room?

A

AC is narrowest in the dark due to the peripheral muscles thickening and a more convex iris, and so the risk of angle closure glaucoma is greatest under dim illumination.

39
Q

Name 7 other gonioscopy findings that may be seen.

A

Synechia: uveitis
Pigmentation: pigment dispersion syndrome
Pseudofoliative material
Blood vessels: neovascularisation
Particles
Blood: post trauma
Inflammatory deposits: keratic precipitates

40
Q

What are iris processes? What age group are they seen highest in? Where to they begin and project to?

A

They are normal anomalies, seen most in childhood and wither with age.
Begin at the iris periphery and bridge the CB and insert into the TM.

41
Q

Where do anbormal iris processes insert into?

A

Schwalbes line

42
Q

Name 7 contraindications of gonioscopy, and why if applicable.

A 
Anaesthetic reaction
-self explanatory
Lacerated or perforated globe
-Pressure will cause aqueous to drain out of the eye
Hyphaemia
-Will cause a rebleed
Pregnancy
-Reduced corneal healing
Corneal/Conjunctival infection or epithelial basement membrane dystrophy
-Corneal epithelium already weak
43
Q

What 6 things can an OCT scan give information about?

A 
CCT
Corneal curvature
AC depth
AC volume
Iris angle
Plateau iris

OD1 - Integrated Ophthalmic Sciences & Preclinical Optometry (123 decks)

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