Gonioscopy Flashcards
van herrick angle estimation is a ratio of what?
ratio of width of peripheral AC to the width of the cornea
what can a deep anterior chamber suggest?
may be suggestive of pigment dispersion syndrome
define gonioscopy
a procedure used in the evaluation of the peripheral anterior chamber angle
indications for gonioscopy
- evaluation of narrow anterior chamber angle prior to dilation
- differential diagnosis of angle closure
- differential diagnosis of open angle GLC
- evaluation of iris contour changes
- rule out neovascularization of the iris
- history of blunt trauma
contraindications for gonioscopy
- hyphema
- recent refractive surgery
- compromised corneas (epithelial damage)
- perforated eyes
- lacerations
list 3 mirrors of the goldmann 3 mirror lens
- apical mirror (bullet)
- peripheral mirror (square)
- equatorial mirror (trapezoid)
mirror and degree used in angle viewing and ora serrata
apical (bullet), 59 degrees
mirror and degree used in peripheral retinal evaluation
peripheral mirror (square), 67 degrees
mirror and degree used in equatorial retinal region evaluation
equatorial mirror (trapezoid), 73 degrees
which mirror system is more versatile, clearer views, better for blepharospasm, and adheres to the eye on the central axis?
3 mirror
which mirror system is used for compression gonioscopy
4 mirror
which mirror system uses little to no fluid, has a rapid assessment of the angle, is less traumatic to the eye, but requires more dexterity
4 mirror
what can indentation or compression gonioscopy assess and be used for?
- assess if appositional closure or PAS present
- can be used to break ACG attack, lower IOP
how does indentation or compression gonioscopy work?
directs aqueous towards the peripheral anterior chamber and pushes the peripheral iris back to view the angle
how does “dynamic gonioscopy” and what does it allow for?
- allows for a better view over a very convex peripheral iris
- tilt or slide the lens towards the angle being viewed or have patient look into the mirror
list structures you see in gonioscopy from posterior to anterior
-iris
-ciliary body
-scleral spur
-trabecular meshwork
(pigmented then non-pigmented)
-Schwalbe’s line
color, width and visibility of ciliary body
color: light grey to light brown, charcoal grey in darker irides
width: 0.5 mm (wider may indicate angle recession)
visibility: may be obscured by iris processes or iris
what is the scleral spur and what is the color/ appearance?
- a fibrous ring that attaches the CB to TM
- color is white and appearance is a radial ring that may be obscured by iris or iris processes
which structure of the trabecular meshwork is most posterior?
pigmented
what is important about the pigmented structure of the trabecular meshwork?
- filtering portion of the angle
- Schlemm’s canal next to SS
when is Schlemm’s canal visible?
when episcleral venous pressure increases
red
pigment in the TM does not occur before:
puberty
when does pigment in the TM increase?
- in pregnancy
- with age
- with iris colors
list some other related changes to pigment in the TM
- pigment dispersion syndrome
- previous injuries or surgeries
- exfoliation
- open angle glaucoma
- previous uveitis
list grading scale and definitions for pigment in TM
0- granular, fine, gray color trace 1+: scattered pigment/ slightly brown 2+: definitely visible brown pigment 3+: dense pigment band 4+: pigment on the iris, SS, CB (extremely thick and dense)
what is the “termination of Descemet’s in the angle?
Schwalbe’s Line
What is the anterior limit of the angle wall and the junction of the anterior and posterior cornea lines
Schwalbe’s Line
describe the appearance of Schwalbe’s line
thin white glistening line which acts as a “shelf” where pigment may collect inferiorly
what is posterior embryotoxon
15% of eyes have Schwalbe’s line anteriorly displaced
when evaluating Schwalbe’s line, what is “Sampaolesi’s line”?
a wavy line of pigment seen in exfoliation patients
list 3 common “sightings” in the angle
- iris processes
- sampaolesi’s line
- blood in Schlemm’s canal
the unwanted “guests” in the angle
- synechiae
- neovascularization (diabetic retinopathy)
3 reasons why you may see blood in schlemm’s canal
- excessive pressure from gonio lens
- increased episcleral venous pressure
- low IOP
what should you look for and what conditions can cause blood in Schlemm’s canal from increased episcleral venous pressure
look for engorged episcleral veins
- cavernous sinus fistula
- thyroid disease
- Sturge-Weber
Becker Shaffer 4
ciliary body
Becker Shaffer 3
scleral spur
Becker Shaffer 2
anterior TM
Becker Shaffer 1
anterior TM/ SChwalbe’s line
Becker Shaffer 0
no visible structures
what is the Spaeth criterion?
alphanumeric documentation
- details 3D dimensional details of the angle
- high correlation to OCT and UBM findings
how you you grade in Spaeth criterion?
made up for sup (narrowest) and inferior (widest)
- site of iris insertion
- angle width
- configuration of peripheral iris
- trabecular meshwork pigment
iris insertion in Spaeth criterion grading
A- anterior to Schwalbes B- behind Schwalbes and scleral spur C- scleral spur visible D- deep CB visible E- extremely deep >1mm of CB visible
with of angle recess in Spaeth criterion grading is:
width of angle recess can be 0, 10, 20, 30, 40
peripheral iris configuration for Spaeth criteria
- steep (bowed (b) or plateau (p))
- regular or flat
- queer or concave
pigment in TM for Spaeth criteria
minimal to no pigment: grade 1
up to dense pigment: grade 4
list of angle closure from slight risk to extremely risky
- TM without iris bow
- TM with iris bow
- 1/2 TM without iris bow
- 1/2 TM with iris bow
- Schwalbe’s line
documentation requirements
- which eye, which angle
- most posterior structure
- about of pigmentation
- iris approach (flat, moderate or bowed)
- angle anomalies (iris processes, sampolesis line, pigment above Schwalbes)
convexity more common in
hyperopia, malignant glaucoma, plateau iris, angle closure
increases in cataract
concavity more common in
myopia, aphakia, pigment dispersion
irregular iris in
synechiae, iris or CB tumor, lens dislocation, iris cyst
gonio billing specifics
92020
(OU, 1x/year)
-can code with 92012
-need to have associated code (narrow angles, glaucoma suspect, glaucoma)
problems with Van Herick:
- only measures “apparent depth”
- iris appears closer
- typically underestimating angles
what is the SL-OCT good for?
- angle assessment
- iris configuration
