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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
E. Schlemm’s Canal
1. Lies at the base of the scleral sulcus (not visible)
2. Drains into venous system
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)
2. 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
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
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
3. Pull lower lid down with patient in up-gaze
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
5. Corneal wedge
H. Lens Removal
1. Break seal
2. Irrigation of coupling solution
I. Check corneal integrity
VI. Grading Systems
A. Shaffer System
1. Angle between iris and trabecular meshwork
B. Spaeth System
1. Level of iris contact to wall of angle
2. Width of angle
3. Configuration of iris
C. Scheie System
1. Angle structures visible
2. Angle 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
1. History of acute angle closure in fellow eye
2. Appositional closure with indentation gonioscopy
3. IOP increase and angle closure with dilation
4. Symptoms suggesting subacute angle-closure attacks
a) Transient blur
b) Halos
c) Ocular pain or frontal headache
5. 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)