GONIOSCOPY

SMITA BANERJEE

Sankara Nethralaya,

Kolkata

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DEFINITION

Gonioscopy describes the use of

gonioscope to gain a view of the

anatomical angle formed between the

eye's cornea and iris.

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PURPOSE

It permits differential diagnosis of the glaucoma

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HISTORY

Trantas (1907) coined the term Gonioscopy

Salssmann (1914) first performed Gonioscopy

Goldmann (1938) first introduced gonioprism

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INDICATIONS Increased intra-ocular pressure IOP normal ; AC angle shallow (VHr II or less) or

historical evidence of angle closure Diagnosed e/w as glaucoma or using any anti-

glaucoma medication Family History of glaucoma Patent/ partially patent Peripheral Iridectomy

done e/w with increased/normal IOP

e/w = else where , VHr = Van herick

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INDICATIONS History of Blunt Ocular trauma

Extent of Rubeosis iridis

Diagnosed else-where as CRVO & BRVO

Conditions like PAS, ciliary body cyst tumors of the anterior segment

Pseudo-exfoliation

PAS = peripheral anterior synaechia

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CONTRA-INDICATIONS

Hyphema

Corneal oedema

Corneal epithelial defect

Penetrating injury

Foreign body

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PRINCIPLE

Rays coming from angle of anterior chamber Strikes corneal interface at more than 45o

Rays are totally internally reflected Helps to neutralize the corneal refractive

power and allows visualization of angle structure

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TYPES OF GONIOSCOPY Indirect : angle

viewed in mirror mounted on a gonioprism

Direct : angle viewed directly

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DIRECT GONIOSCOPY

TECHNIQUE:1. Koeppe lens (50D concave lens )is the

prototype direct gonio lens2. Patient is in recumbent position3. Placed on anaesthetized patient’s cornea4. Saline or viscous gel is used to fill the interface5. Slit lamp or binocular magnifier used for

viewing6. SWAM-JACOB lens commonly used as

surgical lens

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DIRECT GONIOSCOPY

ADVANTAGES:

1. Direct visualization of angle shows normal view

2. View of the entire circumference

3. Easy to look down over the convex iris

4. Used for Goniotomy & Goniosynchialysis

DIS-ADVANTAGES:

1. Cumbersome

2. Supine position

3. Costly Equipment

4. Time Consuming

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Direct Gonio Lenses:

1. Koeppe Prototype diagnostic goniolens

2. Richardson Shaffer For infants

3. Layden For premature infants

4. Hoskins Barkan Prototype surgical & diagnostic lens

5. Thorpe For operating room

6. Swan Jacob Surgical lens

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Hoskins Barkan Gonio lens

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IN-DIRECT GONIOSCOPY

TECHNIQUE:1. Patient is positioned on slit-lamp with

anesthetized cornea

2. Patient is asked to look down or upward and quickly lens is tipped forward against cornea.

3. Slit lamp is placed perpendicular to the pupil4. Slit-lamp beam used should have least

possible illumination & magnification

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IN-DIRECT GONIOSCOPY

ADVANTAGES:

Convenient to use

Manipulation and indentation possible

DIS-ADVANTAGES:

Cannot compare both eyes simultaneously

Needs co-operation of patient

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In-direct Gonio Lenses:1. Goldmann Single mirror Mirror inclined at 62o

2. Goldmann three mirror Mirror inclined at 59o

3. Zeiss four mirror Mirror inclined at 64o

4. Posner four mirror Modified Zeiss with handle

5. Sussmann four mirror Finger (hand) held Zeiss type

6. Thorpe four mirror 4 Mirrors inclined at 62o ; requires fluid bridge

7. Ritch Trabeculecoplasty lens

2 mirrors at 59o &2 at 62o with convex lens over two

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PROCEDURE OF INSERTION OF GONIOSCOPE

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DYNAMIC GONIOSCOPY

Indentation –

1. Can be done with 4 mirror lens

2. Central corneal compression is done.

Manipulation –

1. Patient asked to look in direction of mirror

2. Mirror tilted towards the angle viewed

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INTERPRETATION OF ANGLE Schwalbe’s Line: 1. Termination of Descemet's membrane 2. Looks like a thin, glistening white line; may be

pigmented Trabecular meshwork (TM) 1. Translucent and light grey2. Darkens with age 3. Schlemm's Canal (SC) or Canal of Schlemm –

i. Covered by the filtering portion of the TM May be seen as a light grey line in translucent TM

ii. Most pigmented band of TM (post 2/3 of TM) corresponds to canal of Schlemm

iii. Will occasionally fill with blood when pressing on globe

iv. Only clearly visible if filled with blood

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INTERPRETATION OF ANGLE Scleral spur (SS) 1. Represents continuation of the sclera into the AC 2. Attached anteriorly to the TM and posteriorly to

the sclera3. SC lies just anterior to SS 4. Appearance: Thin, whitish band (Prominent white

line) Ciliary body band (CBB) 1. Coloration; Color varies between individuals 2. CBB is broader inferiorly and temporally

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Other considerations in assessing the Anterior Chamber Angle

Observation begins at the pupillary border

1. Blood vessels

2. Deposition of exfoliation material

3. Iris atrophy

4. Iris cysts Note contour of the iris plane - Is it flat, concave, or

convex Angular approach

1. Refers to the width of the angle recess

2. Angle recess

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Other considerations in assessing the Anterior Chamber Angle To obtain clearer views - Make sure slit lamp beam is parallel to the

axis of the mirror & Front of the goniolens should be perfectly straight To avoid getting bubbles 1. an adequate amount of solution is used2. Do not tilt the lens excessively or have patient look at extremes of field

of gaze 3. Press the lens firmly against the cornea To remove bubbles 1. Tilt (rock) the lens slightly back and forth2. Have the patient look toward the bubble3. Have the patient alter field of gaze while pressing against the cornea

with the lens Decrease IOP with gonioscopy by forcing aqueous out of the

anterior chamber

3 2 1

0 4

Shaffer grading of angle width

Clinical Interpretation ………………………… Grade 4 : closer impossible Grade 3 : closer impossible Grade 2 : closer possible Grade 1: closer likely with full

dilation Grade 0: closed

Grade 4 (35-45 )Ciliary body easily visible Grade 3 (25-35 ) scleral spur

visible Grade 2 (20 )- Only trabeculum

visible Angle closure possible but unlikely

Grade 1 (10 ) - Only Schwalbe line and perhaps top of trabeculum visible; High risk of angle closure

Grade 0 (0 )- Iridocorneal contact present ; Apex of corneal wedge not visible;Use indentation gonioscopy

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