Angle Anatomy & Aqueous Humor Outflow

ciliary body band

• appearance:

  • light gray to dark brown

  • extends from ora serrata to SS

  • width varies depending on iris contour

• function:

  • aqueous humor production

• most posterior structure of angle

scleral spur

• appearance:

  • white or gray band

  • prominent b/t the darker CB & TM

• function:

  • point of attachment b/t sclera & ciliary muscles

trabecular meshwork

• appearance:

  • gray to brown band

  • anterior is more pigmented than the posterior

• function:

  • drainage of aqueous humor

• Schlemm’s canal lies behind posterior 2/3 of TM

Schwalbe’s line

• appearance:

  • thin, glistening white line

• function:

  • marks the end of Descemet’s membrane

  • transition from cornea to sclera

iris, ciliary body band, scleral spur, trabecular meshwork, Schwalbe’s line

list the structures of the angle from most posterior to anterior

4

• angle width: 35-40deg

• most posterior structure: CB band

• description: wide open

• probability of closure: impossible

3

• angle width: 20-35deg

• most posterior structure: CB band or scleral spur

• description: open

• probability of closure: improbable

2

• angle width: 10-20deg

• most posterior structure: scleral spur/TIM

• description: narrow

• probability of closure: possible

1

• angle width: 10deg

• most posterior structure: anterior TM

• description: extremely narrow

• probability of closure: probable

0

• angle width: 0deg

• most posterior structure: none

• description: closed

• probability of closure: closed

inferior

which angle is the widest?

superior

which angle is the narrowest?

temporal

which mirror is usually more narrow than the others

direct gonioscopy

• uses Koeppe lens

• high plus CL

• allows for 360 visualization of the angle

• not commonly performed b/c pt must be supine & circle the supine pt while observing with a handheld slit & separate light source

3 mirror indirect gonioscopy

• contains 2 mirrors to view retina & 1 to view AC angle

• central Hruby lens that shows the posterior pole

• advantages:

  • good stability

  • excellent optics

  • used for AC angle evaluations & posterior & peripheral fundus eval

• disadvantages:

  • must rotate to see all the angles

  • increased exam time

  • may increase pt discomfort

  • insertion & removal are more involved

4 mirror indirect gonioscopy

• all 4 mirrors have the same angle & used to view AC angle only

• central Hruby lens that shows posterior pole

• can have a handle or not

• can have a flange or not

• advantages:

  • can view all quadrants of the same angle w/o needing to rotate

  • more user & pt friendly

  • may be used for indentation gonio

• disadvantages:

  • no mirrors for peripheral fundus view

  • requires greater operator skill

d shaped mirror

• 60deg angle

• offers view of AC angle

rectangular mirror

• 66deg angle

• offers views of the retina b/t the equator & beginning of ora serrata

trapezoidal mirror

• 76 deg angle

• offers view of the retina b/t the posterior pole & equator

Scwalbe’s line

when doing the corneal wedge technique, what structure is highlighted?

posterior embryotoxon

• normal finding

• thickened Schwalbe’s line

• benign finding in ~20% of population

• most often associated with pathological findings of the iris & cornea

iris processes

• normal finding

• fine, lacy projections of peripheral iris tissue extending to the sleral spur or TM

• easily seen in brown eyes

• does not impede TM outflow

peripheral anterior synechiae

• abnormal finding

• adhesions of the peripheral iris to the angle wall

• very thick fibers that extend from iris root to SS/TM/Sl

• not always present 360deg

• associated w/ closed angles & past or present inflammation

• large areas can be problematic

indentation gonioscopy

used to distinguish b/t an angle closed by pupillary block & peripheral iridotomy; typically done with a 4 mirror

pigmentary dispersion syndrome

• findings:

  • Kruckenberg spindle

  • transillumination defects

  • sampolesi’s line

• demographics:

  • more common in males

  • males present in 30s

  • females present in 40s

  • more common in myopes

  • associated w/ concave iris & posterior iris insertions

  • pt have significantly flatter corneas

• pathology:

  • iris touches lens zonules, resulting in iris pigment being rubbed off & entering the AC, clogging the TM

pseudoexfoliation syndrome

• flaky material on anterior lens capsule at pupillary margin

• material builds up in angle

• frosting of lens zonules

hyphema

collection of blood in the AC due to trauma; risk of increased IOP

angle recession

due to trauma, further back AC angle; small percentage develop glaucoma

PDS

trans-illumination defects of the mid-peripheral iris are most commonly associated with what condition?

CB to left of iris, then SS, TM, SL

when viewing the temporal angle of the pt’s left eye with the 4 mirror gonio lens, how are the structures seen in the mirror?

schwalbe’s line

in the event of an anterior chamber angle closure, which structure would you most likely see with the 3 or 4 mirror gonio lens?

indentation gonioscopy with an un-flanged 4 mirror goniolens

on a 3 mirror gonio, you determine that the anterior chamber is completely closed 360deg, how would you distinguish if the angle was held closed by PAS or if it could potentially be opened by laser surgery?

trapezoidal mirror

if you want to view the mid-peripheral retina, which element of the 3 mirror goniolens would you use?

the limbus prevents a direct view of the AC angle, as do internal reflections

why was gonio developed?

ciliary body

in the event of an anterior chamber angle closure, which structure would you least likely see with 3 or 4 mirror goniolens?

rectangular mirror

if you want to view the peripheral retina, which element of the 3 mirror goniolens would you use?

performs a 4 mirror gonio & finds ½ the TM in at least 2 quadrants

with angles that appear narrow using Van Herick angle estimation, it is safest to proceed with dilation when the clinician does what?

d shaped mirror

if you want to evaluate the pt’s AC angle for damage following trauma, which mirror on the 3 mirror goniolens should be used?

ciliary body

angle structure best described as a brown band when viewed during gonio & is responsible for producing the aqueous humor

trabecular meshwork

angle structure that is best described as a gray to brown band when viewed during gonio & is responsible for the filtering portion of the angle

pseudo-exfoliation syndrome

TID of the pupillary margin are most commonly associated with what condition?

scleral spur, grade 2

what is the most posterior structure in this image & what would you grade it?

ciliary body band

what is the most posterior structure in this image

ciliary body band

what is the most posterior structure in this image

schwalbe’s line, grade 0

what is the most posterior structure in this image & what is the grade

ciliary body band

what is the most posterior structure in this image

iris processes

what is the finding shown in this image?

iris processes

what is the finding shown in this image?

neovascularization of the angle

what is the finding shown in this image?

blood in schlemm’s canal

what is the finding shown in this image?

pigment deposition from PDS or PXS

what is the finding shown in this image?

ciliary body band, grade 4

what is the most posterior structure shown & what is the grade?

Schwalbe’s line, end of descemet’s membrane & transition from cornea to sclera

what is the most posterior structure shown here & what is the function?

posterior pole of the retina

the central Hruby lens of the 3 & 4 mirror goniolenses is used to view what?

ciliary body band

identify the red arrow structure

schwalbe’s line

identify the purple arrow structure

scleral spur

identify the blue arrow structure

trabecular meshwork

identify the green arrow

posterior embryotoxin

identify

iris processes

identify

peripheral anterior synechiae

identify

PDS Kruckenberg spindle

identify

TID

identify

TID from PDS

identify

pigment deposits in angle from PDS

identify

pseudo exfoliation syndrome

identify

blood in Schlemm’s canal

identify

neovascularization

identify

neovascularization

identify

MIGS

identify

ALT

identify

8 ball hyphema

identify

general hyphema

identify

angle recession

identify

angle recession

identify

anterior synechiae

identify

anterior synechiae

identify

anterior synechiae

identify

neovascularization of the angle

identify

ciliary body band, aqueous humor production

identify the most posterior structure shown in this image & what is its function?

Schwalbe’s line, trabecular meshwork, scleral spur, ciliary body

list the angle structures from most anterior to most posterior