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Glaucoma > Lecture 6: Gonioscopy, Ultrasound, Biomicroscopy, Angle Imaging > Flashcards

Lecture 6: Gonioscopy, Ultrasound, Biomicroscopy, Angle Imaging Flashcards

1
Q

Which goniocope has better optics and stability of image? (3 mirror/4 mirror)

A

3 mirror

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2
Q

What is the purpose of gonioscopy specifically for glaucoma?

A

Differentiate between POAG & PACG

  • Diagnose
    • Congenital
    • Secondary
    • Angle recession
    • Uveitic
    • Neovascularization
    • ICE (Iridocorneal endothelial syndrome)
    • tumors & cyst
    • trauma & FB
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3
Q

What are the 6 key structures to evaluate during gonioscopy?

A
  • Pupil border
  • Peripheral iris
  • Ciliary body band
  • Scleral spur
  • Trabecular meshwark
  • Schwalbe’s line
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4
Q

Label the image

A
  1. Pupil border
  2. Iris periphery
  3. Ciliary body
  4. Scleral spur
  5. Trabecular meshwork
  6. Schwalbe’s line
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5
Q

Ciliary body band is the most (anterior/posterior) structure

A

posterior

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6
Q

Where is the insertion point of the iris root located?

A

ciliary body

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7
Q

Width of the ciliary body depends on the position of iris insertion. Tends to be narrower in ___ eyes & wider in ___ eyes.

A

hyperopic, myopic

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8
Q

Angle recess represents the dipping of the ______________.

A

iris as it inserts into the ciliary body

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9
Q

____ is the most anterior pont of the sclera

A

Scleral spur

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10
Q

Where is the site of attachment of the longitudinal muscle of the ciliary body located?

A

Scleral Spur

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11
Q

Gonioscopically, the scleral spur is (posterior/anterior) to TM

A

posterior

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12
Q

This angle structure appears pink/dull brown/slate gray

A

ciliary body

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13
Q

This angle structure appears as a narrow, dense, shiny whitish band

A

scleral spur

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14
Q

Scleral spur is necessary to hold ___ open. What happens if the scleral spur is shortened?

A

Schlemm’s canal

  • Shortened scleral spur may reduce mvmt & allow collapse of schlemm’s canal
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15
Q

Trabecular meshwork extends between what 2 structures?

A

Scleral spur & schwalbe’s line

  • Posterior adjacent to scleral spur
  • Anterior adjacent to schwalbe’s line
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16
Q

In trabecular meshwork which portion is the functional pigmented part & which portion is the nonfunctinonal part?

A
  • The posterior is the functional pigmented part
    • Grayish to translucent appearance if absent pigment
  • The anterior is the nonfunctional part lies adjacetn to Schwalbe’s line
    • Pale/whitish color
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17
Q

Which part of the angle does pigment accumulate with increasing age?

A

TM

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18
Q

What are iris processes?

A

small extensions from the anterior surface of the iris

  • Uveal extensions from iris to TM
  • Insert at level of scleral spur and cover the ciliary body to varying extent
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19
Q

Iris processes are found in __% of people

A

35

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20
Q

What are the three types of grading chamber angle? Describe each

A
  • Scheie grading: most posterior structure visible
  • Shaffer system: assess geometric angle width in 4 grades angle potential for occlusion
  • Spaeth system: spaeth system: 3D structure of angle - level of iris insertion and peripheral iris configuration
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21
Q

If the gonio angle is compressed too hard on the eye, this angle structure can fill up with blood

A

Schlemm’s Canal

  • the episcleral veins and episcleral venous pressure exceeds IOP
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22
Q

This may be identified in the non-pigmented angle as a slightly darker line deep to the posterior trabecular meshwork

A

schlemm’s canal

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23
Q

Describe the composition of the schlemm’s canal (3)

A
  • Endothelial cells surrounded by CT
  • internal collector channels
  • connected to episcleral & conjunctival veins via exeternal collector channels, intrascleral venous plexus, deep scleral plexus & aqueous veins
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24
Q

When would a blood vessel be abnormal when looking at the angle of the eye?

A
  • When blood vessels cross scleral spur onto the TM is abnormal
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25
Q

Vessels run a ___ pattern

A

radial

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26
Q

Describe Scheie Grading System

A
  • grading system is baesd on visible structures
  • Scheie granding system is verversed relative to Shaffer system
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27
Q

What is the most anterior angle structure?

A

Schwalbe’s line

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28
Q

Which angle structure marks the transition from transparent cornea to opaque scleral tissue?

A

Schwalbe’s line

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29
Q

Appear as an opaque line

A

Schwalbe’s line

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30
Q

This structure represents the peripheral termination of descemet’s membrane & anterior limit of trabecula

A

Schwalbe’s line

31
Q

What lies just anteriorly to schwalbe’s line?

A

Sampaolesi’s line

32
Q

Grading of the angle main aims are to evaluate what? (3) & is important to determine what? (5)

A

Main aims:

  • functional status of the angle
  • degree of closure
  • risk of further closure

It is important to determine:

  • Angle width
  • Shape & contour of the peripheral iris
  • Most posterior structure seen
  • Presence of peripheral anterior synechiae (PAS)
  • Amount of trabecular pigmentation
33
Q

Describe Shaffer grading system

A
  • Grades angle width in degrees, and risk of closure
  • Does not provide information on iris shape or level of insertion
34
Q

Describe Spaeth grading system

A
35
Q

Describe pigment grading

A
  • grade amount of pigment present in the TM
  • Greater pigment = increase risk of aqueous blockage
36
Q

Describe grading of the iris approach

A
37
Q

Abnormal gonioscopic findings may include

A
  • Peripheral angle synechiae (PAS)
  • Excessive pigmentation
  • Blood vessels (cross scleral spur –> TM)
  • Angle recession
38
Q

What is Peripheral Anterior Synechiae (PAS)? What causes PAS? (6)

A
  • Adhesion of the iris root to the TM, scleral spur or peripheral cornea
  • May be caused by
    • position angle closure
    • creeping angle closure
    • inflammation
    • neovascular membranes
    • migrating corneal endothelial cells (ICE syndrome: bottom photo)
    • Trauma
39
Q

What can cause excessive pigmentation in the TM

A
  • Pigment dispersion syndrome (PDS)
  • Pigmentary glaucoma (PDG)
  • Pseudoexfoliation syndrome (PXS)
  • Uveitis
  • Trauama
40
Q

Pigment dispersion is (unilateral/bilateral)

A

bilateral

41
Q

What is pigment dispersion?

A
  • Characterized liberation of pigment granules from the iris pigment epithelium and deposition in the anterior surface including zonules & ciliary body
  • Elevation of IOP is caused by pigmentary obstruction of intrabecular spaces and damage to TM
42
Q

What does pigment dispersion look like when performing gonioscopy?

A
  • Wide open angle
  • Concavity of peripheral iris near the insertion
  • Trabecular hyperpigmentation
    • Pigmentation is most pronounced on the posterior TM
    • Dense, uniform band
  • Schwalbe’s line is often pigmented too
    • Pigment heaviest inferiorly
    • Diminishing to almost no pigment superiorly
43
Q

In pseudoexfoliation syndrome, gonioscopy shows what? (5)

A
  • TM hyper pigmentation
  • Pigment greatest inferiorly
  • Pigment lies on surface of TM
  • Pigment has a “patchy” or “chocolate chip” appearance
  • Pigmentation running onto or anterior to schwalbe’s line also known as sampolesi’s line is also frequently seen
44
Q

Always do ___ on patients with CRVO. Why?

A

gonio

  • dont want to miss any neo in angle.. happens here first with these patients
45
Q

Patients with “buds” at the pupillary margin will likely preced __ in the angle

A

neo

46
Q

Don’t apply excessive pressure when viewing neo. why?

A

even light pressure can collapse the tufts of neo and render them clinical invisible

47
Q

What can cause blood in schlemm’s canal?

A
  • pressure from gonio lens - but goes away
  • Pathological
    • cavernous sinus fistual
    • struge weber syndrome
    • obstruction of superior vena cava
48
Q

Always perform gonio on patients with blunt trauma. What should you look for?

A
  • Angle recession
  • Trabecular dialysis
  • Iridodialysis
  • Cyclodialysis
  • Presence of small FB
49
Q

Describe angle recession

A
  • Characterized by marked widening of the CBB
  • important to compare normal to abnormal areas within same eye
50
Q

angle recession is the most common sign of ___

A

post contusional injury - 9% of pt will develop angle recession glc

51
Q

Describe cysts

A
  • incidental finding
  • if asymptomatic = no tx required
52
Q

Describe tumors in the eye

A
  • rare - iris or ciliary body melanoma
53
Q

What is ultrasound biomicroscopy (UBM)

A
  • Non-invasive technique for evaluating the presence of narrow anterior chamber angles, angle closure glaucoma, and ciliary body
  • Direct contact of transducer to the eye or through immersion technique
  • Provides quantitative measurements of the anterior chamber angle (ACA) that are useful for accurate diagnosis and management
54
Q

What are the standard measurements in UBM?

A
  • Angle opening distance (AOD): perpendicular distance between the trabecular meshwor at a point 500um anterior to the scleral spur, and the iris
  • Angle recess area (ARA): triangular area bound between the AOD line and the angle recess
  • Anterior chamber depth (ACD): distance between the central corneal endothelium and the anterior surface of the lens
  • Lens vaults: distance of the lens located anterior to the perpendicular line between the scleral spurs
55
Q

Why would you perform UBM vs gonioscopy?

A
  • Detailed
  • Pt dark adapted
    • Changes position of angle anatomy
    • May reveal angle closure
  • Can be difficult to determine details via gonio in some cases
    • anatomy can be tough
    • can perform gonio with dim illumination - but difficult to see
  • can assist in diagnosis of ant seg tumors/cyst
  • can assist in the diagnosis of primary angle closure glaucoma
56
Q

UBM is particularly useful to confirm presence of ____

A

iris plateau

57
Q

Describe the image (UBM)

A

Typical UBM section in a patient with wide open angle

58
Q

Describe the image (UBM)

A
  • The posterior concavity of peripheral iris in a patient with pigment dispersion syndrome
59
Q

Describe the image (UBM)

A

Pupillary block

60
Q

What is pupillary block?

A
  • Flow of aqueous from the posterior anterior chamber is inhibited, causing iris bombe
61
Q

What causes pupillary block?

A
  • may be simply due to genetic predisposition & anterior segment anatomy, e.g. convex iris configuration (primary pupil block)
  • OR from posterior synechiae, lenticular enlargement or displacement of the lens or IOL (secondary pupil block)
62
Q

What is the difference between relative vs. absoulte pupil block?

A
  • Absolute is RARE: iris is completely bound down to the lens by posterior synechiae
63
Q

Describe the image (UBM)

A

Pupillary block: e.g. iris bombe

64
Q

Describe the image (UBM)

A

UBM of narrow angle in a patient with acute intermittent angle closure glaucoma due to pupillary block

65
Q

Describe the image (UBM)

A

In this case the iris root touches th peripheral cornea ahead of the trabecula due to pupillary block

66
Q

Describe the image (UBM)

A
  • Incomplete angle closure
    • the angular recess creates an open tunnel, which is located between the iris and trabecula
67
Q

Describe the image (UBM)

A
  • Complete angle closure
    • ​complete occlusion of the TM
68
Q

Describe the image (UBM)

A
  • Plateau iris syndrome
    • ​Flat iris configuration with a sharp bending back at level of the trabecula which gives rise rise to the creation of a particularly narrow angular recess
    • When pupil dilates, the iris tissue bunches up in (crowds). the restricted angular space and closes the angle
69
Q

Patients with plateau iris syndrome need ____.

A

IRIDOPLASTY

  • Iridectomy or laser iridotomy are ineffective. These patients need IRIDOPLASTY
70
Q

Describe the image (UBM)

A
  • Iris & ciliary body cyst
71
Q

What does the AS-OCT standard measure? (6)

A
  • Corneal thickness (CT)
    • distance btw the anterior surface of the epithelium and posterior surface of the endothelium
  • Epithelial thickness (ET)
    • ​distance below tearm film –> above Bowman’s layer
  • Angle opening distance (AOD)
    • ​perependicular distance betwen TM at a point 500u anterior –> scleral spur & iris
  • Angle recess area (ARA)
    • ​triangular area bound between the AOD line and the angle recess
  • Anterior chamber depth (ACD)
    • ​distance btw central corneal endothelium and the anterior surface of the lens
  • Lens vault
    • ​distance of lens located anterior to the perpendicular line between the scleral spurs
72
Q

What are the limitations of AS-OCT? (3)

A
  • Cannot penetrate iris
  • Can not define scleral spur 25% of time
    • therefore can not accurately define angle anatomy
    • Therefore our diganosis may be wrong 25% of time
  • Uses light to obtain the image so angle anatomy will be altered
73
Q

What is the difference between AS-OCT vs. UBM

A
  • Both angle imaging technologies
  • Both produce cross-sectional images of the anterior segment
  • UBM
    • ​can view ciliary body anatomy
      • huge role in glc diagnosis & tx
    • well established tech
    • more involvement to obtain images
  • AS-OCT​
    • ​higher res images of iris and angle
    • obtaining image is very easy
    • Potential for further development

Glaucoma (11 decks)

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