Gonioscopy Workshop
I. Angle structures (posterior to anterior)
A. Iris
1. Blood vessels in stromal layer with radial orientation
2. Inserts into face of CB posterior to SS (rarely inserts into SS)
B. Ciliary Body
1. Functions: aqueous production/regulation, accommodation, secretion of
hyaluronate into vitreous, blood aqueous barrier
2. Circular muscle fibers (accommodation); Longitudinal muscle fibers
(pulls open TM and Schlemm’s canal)
3. Ciliary body face: portion that borders the anterior chamber; approx 10%
of aqueous outflow is uveoscleral
C. Scleral Spur
1. Site of attachment for the longitudinal muscle of the CB (pulls on spur and
opens TM)
2. Yellows with age
D. Trabecular Meshwork
1. Approx 90% of aqueous flows through TM (varies with age)
i. Deepest layers most resistant to outflow
ii. Anterior meshwork usually non-pigmented, posterior meshwork
becomes more pigmented over time (more flow through posterior
TM)
iii. Most TM pigment is intracellular (ingested through phagocytosis)
E. Schlemm’s Canal
1. Lies at the base of the scleral sulcus (not visible)
2. Drains into venous system
i. Can close under pressure
F. Schwalbe’s line
1. Transition zone between TM and corneal endothelium
2. Transition from scleral curvature to steeper corneal curvature
3. Flat in most eyes but can form a ridge (most often inferior)
II. Normal Variants
A. Iris processes
1. Uveal extensions from the iris to the TM
2. Usually insert close to SS but sometimes extend to Schwalbe’s
3. Usually fine and extend into posterior TM – follow concavity of angle –
do not inhibit iris movement
4. Can be broken in angle recession
B. Sampaolesi’s line
1. Settling of pigment on or anterior to Schawalbe’s line
C. Posterior Embryotoxin
1. Prominent anterior Schwalbe’s line
2. Usually a normal variant, but can be associated with Axenfeld-Rieger
Syndrome
D. Blood in Schlemm’s canal
1. Can occur if large diameter CL compresses episcleral veins or when IOP
is low and episcleral pressure high
E. Angle Vessels
1. Normally have radial orientation in iris and normal caliber
(neovascularization would be fine and often crosses the scleral spur)
F. More visible in light irides
III. Indications
A. Visualize anterior chamber structures and depth
B. Angle closure
C. Angle recession
D. Synechia
E. Neovascularization
F. Neoplasms
G. Trauma
IV. Direct Gonioscopy
A. Steep contact lens (Koeppe, Hoskins-Barkan, Swan-Jacobs) – light from angle
exits eye nearly perpendicular to lens/air interface
1. Surgical procedures, exams under sedation
B. Indirect Gonioscopy
C. Mirrors overcome total internal reflection
1. Light exits perpendicular to lens/air interface
D. Goldmann three-mirror lens
1. Fundus lens
2. Thumbnail (59 deg) for viewing angle and ora serrata
3. Rectangular (67 deg) for viewing equator to ora
4. Trapezoid (73 deg) for viewing post pole to equator
5. View angle opposite mirror
6. Coupling solution
E. Four-mirror lenses
1. With and without handles
2. No coupling solution required
3. Four quadrants visible, 11 deg rotation to complete view
4. Indentation gonioscopy
a) Due to small area of contact with cornea, angle can be deepened
with pressure
b) Distinguish between synechial and appositional closure
c) Difficult when IOP high
F. One-mirror, two-mirror and laser lenses
1. Concentrate laser energy
2. Convex buttons to increase mag
3. Broader viewing area
V. Procedure
A. Lens preparation
1. Clean with mild cleaning solution (diluted dish detergent) and soft cloth
2. Sterilize with Gluataraldehyde 2% aqueous solution (soak 25 min) or
Sodium Hypochlorite (household bleach) 10 parts water, 1 part bleach (25
minutes)
3. Alcohol, peroxide and acetone may damage lens surface
4. Coupling solution
a) Methylcellulose
b) Carboxymethylcellulose
c) Store upside down
B. Patient Positioning (allow for enough vertical range with slit lamp)
C. Check corneal integrity
D. Anesthetic
E. Microscope
1. Light source zero degrees (perpendicular to pupil)
2. Low/med mag
3. Parallelpiped (vert sup and inf views, horiz nasal and temp) – approx 4
mm width
F. Application of lens
1. Hold with thumb and forefinger
2. Mirror positioning
a) Mirror is opposite of structure in view
3. Pull lower lid down with patient in up-gaze
a) Rest lens on lower lid margin
b) Tilt lens onto cornea as patient looks straight ahead
c) Support hand on forehead rest or cheek
4. Rotation of lens
a) Hold with three fingers of one hand
G. View Angle
1. Beam perpendicular to base of mirror
2. Glare, bubbles
3. Descemet’s folds = too much pressure
4. Rock lens and change fixation to view more ant or post structures
a) Slide lens in direction opposite of mirror being used to improve
view
5. Corneal wedge
a) Reflection from inner and outer cornea – beam illuminates
interface between cornea and opaque sclera – intersect at
Schwalbe’s line (anterior border of TM)
b) Thin slit lamp beam – slightly offset
H. Lens Removal
1. Break seal
a) Rock lens
b) Look nasal and press on temporal sclera through lid
c) Ask patient to squeeze lids shut
2. Irrigation of coupling solution
I. Check corneal integrity
VI. Grading Systems
A. Shaffer System
1. Angle between iris and trabecular meshwork
a) 4 = 45-35°
b) 3 = 35-20
c) 2 = 20
d) 1 = ≤10
e) Slit
f) 0 = closed°
B. Spaeth System
1. Level of iris contact to wall of angle
a) A = anterior to TM
b) B = behind Schwalbe’s line (in area of TM)
c) C = posterior to scleral spur
d) D = deep into ciliary body face (visible band of anterior CB)
e) E = extremely deep (wide band of CB visible)
2. Width of angle
a) Angle made by line tangential to iris and line tangential to face of
the TM
b) 0-40+°
3. Configuration of iris
a) s = steep or convex
b) r = regular or flat
c) q = queer or concave
C. Scheie System
1. Angle structures visible
a) O = entire angle visible with wide ciliary body band
b) I = iris obscures part of ciliary body
c) II = nothing posterior to TM visible
d) III = posterior TM not visible
e) IV = no structures posterior to Schwalbe’s line visible
2. Angle pigmentation
a) 0 (no pigmentation) to IV (heavy pigmentation)
VII. Laser Peripheral Iridotomy
A. Indications
1. Acute angle closure glaucoma
2. Chronic angle closure glaucoma
3. Aphakic or pseudophakic pupillary block
B. Prophylactic treatment
4. History of acute angle closure in fellow eye
5. Appositional closure with indentation gonioscopy
6. IOP increase and angle closure with dilation
7. Symptoms suggesting subacute angle-closure attacks
a) Transient blur
b) Halos
c) Ocular pain or frontal headache
8. Anxiety about spontaneous angle closure
VIII. Management of Acute Angle Closure
A. Topical Beta-blocker 0.5% and or Apraclonidine 0.1% (single dose)
1. Check pressure q15-30 minutes
B. Compression gonioscopy to temporarily open angle and force fluid into TM
C. Prednisolone Acetate 1% (q15-30 min x 4 doses then hourly)
D. Oral Acetazolamide 500mg (two 250mg tablets)
E. Hyperosmotic agents: 3-5oz oral glycerin or isosorbide over ice
F. Pilocarpine 1-2% only in cases of phakic pupillary block or angle crowding
1. Q15 minutes x 2 doses
2. Do not use in aphakic or pseudophakic pupillary block or mechanical
closure of angle
G. Maintain pressure with medical treatment as necessary and refer within 1-3 days
1. Topical Beta-blocker 0.5% bid
2. Acetazolamide 500mg sequel po bid
3. Prednisolone Acetate 1% q 1-6h
4. Pilo 1-2% qid (phakic pupil block or angle crowding)