Gonioscopy: A Review

doi:10.4236/ojoph.2013.34025

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Open Journal of Ophthalmology, 2013, 3, 118-121

Published Online November 2013 (http://www.scirp.org/journal/ojoph)

http://dx.doi.org/10.4236/ojoph.2013.34025

Open Access OJOph

Gonioscopy: A Review

Parul Singh, Manoj Tyagi, Yogesh Kumar, Krishna Kuldeep, Parmeshwari Das Sharma

V. C. S. G. G. M. S. & R. I., Srinagar, India.

Email: [email protected]

Received January 23rd, 2013; revised February 24th, 2013; accepted March 15th, 2013

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Gonioscopy allows us to examine the angle of anterior chamber and forms part of complete ophthalmic examination

and it is mandatory for the diagnosis and management of glaucoma. Gonioscopy permits the identification of eyes at

risk for closure and detects angle abnormalities that could have diagnostic and therapeutic implications. Principle, types

and techniques of gonioscopy, various types of gonioscopic lenses used, indications of performing gonioscopy, gonio-

scopic anatomy and grading are discussed in this article.

Keywords: Gonioscopy; Anterior Chamber Angle; Goniolens

1. Introduction

Gonioscopy is the examination of the angle of the ante-

rior chamber and is mandatory for the management of

glaucoma. Gonioscopy permits the identification of eyes

at risk for closure and detects angle abnormalities that

could have diagnostic and therapeutic implications. Prin-

ciple, types and techniques of gonioscopy, various types

of gonioscopic lenses used, indications of performing go-

nioscopy, gonioscopic anatomy and grading are dis-

cussed in this article.

2. Evolution of Gonioscopy

The term “Gonioscopy” was coined by Trantas in 1907

[1,2], while Salzmann was the first person to study the

optics behind gonioscopy and to use lens for viewing

angle in 1914 [1,2]. He is thus known as “Father of Go-

nioscopy”. In 1919, Koeppes used the zeiss slit-lamp

to examine angle with his newly developed direct con-

tact lens [3]. Trancoso is credited for development of a

self-illuminating monocular gonioscope in 1925 [4]. It

was approximately two years later in 1927 that the an-

gle was first photographed by Thorburn [5]. Gonioprism

was introduced by Goldmann in 1938. It was Barkan-

who established the use of gonioscopy in goniotomy [6-

8].

3. Principle of Gonioscopy

Without a gonioscope, the rays coming from the anterior

chamber angle strikes the corneal interface at an angle

that exceeds the critical angle, and is thus totally inter-

nally reflected. The gonioscope lens changes the inter-

face from cornea-air to lens-air, changing the critical

angle, thus permitting viewing of angle.

4. Techniques of Gonioscopy

4.1. Direct Gonioscopy

Direct gonioscopy is performed with gonioscopic lenses

used with portable slit-lamp or an operating microscope.

It is done in supine position after instilling topical anaes-

thesia, though it can be done under general anaesthesia

too. Goniolensis positioned on cornea using a bridge of

balanced salt solution and viscous preparation. Examiner

holds goniolens in one hand and light source in another

during the procedure. It provides panoramic view of the

entire circumference and is very useful to compare the

angles of two eyes by looking at them simultaneously. It

can also be used for goniotomy and gonio-synechialysis.

4.2. Indirect Gonioscopy

Indirect gonioscopy uses mirrors or prisms to overcome

the problem of total internal reflection. Patient is posi-

tioned on slit lamp and topical anaesthesia is instilled.

Gonioprismis placed against cornea with or without use

of fluid as bridging agent and rotated to see angles using

slit-lamp illumination and magnification.

Gonioscopy: A Review 119

5. Direct vs Indirect Gonioscopy:

Advantages and Disadvantages

Direct gonioscopy Indirect gonioscopy

The procedure is done in supine

position.

The procedure is done in

sitting position.

Provides less magnification as

compared to indirect gonioscopy. Provides more magnification

of the two procedures.

Patient is more comfortable

during procedure. Lesser patient comfort.

Binocular comparison is possible

in direct gonioscopy.

Binocular comparison is not

possible.

The procedure can be used for

goniotomy and

goniosynechialysis.

Indirect gonioscopy can’t be

used for surgical procedures.

Direct gonioscopy is performed with steep convex lenses

used along with portable slit-lamp or an operating mi-

croscope. This procedure has its significance in simul-

taneous observation and comparison of bilateral anterior

chamber angles. This is essentially used for examination

of children under anaesthesia and for surgical procedures

like goniotomy. Indirect gonioscopy uses mirrors or prism

along with slit-lamp to examine angle of anterior cham-

ber. This is a procedure useful even in out patient de-

partment for examination of angle of anterior chamber.

6. Types of Gonioscopic Lenses

6.1. Direct Gonioscopic Lenses

● Koeppes: prototype diagnostic lens.

● Richardson Shaffer: infants.

● Layden: premature infants.

● Hoskins Barkan: prototype surgical.

● Thorpe: surgical/diagnostic in operation theatre.

● Swan Jacob: surgical for children.

6.2. Indirect Gonioscopic Lenses

● Goldmann single mirror has one mirror inclined at

62˚.

● Goldmann three-mirror has one mirror at 59˚ for

angle, other at 67˚ for pars plana and, third one at 73˚

for oraserrata.

● Zeiss four-mirror has four mirrors all at 64˚ for an-

gle.

● Posner four-mirror is like Zeiss four mirror gonio-

scopewith attached handle.

● Sussmann four-mirror: Handheld zeiss.

● Thorpe four-mirror has all mirrors placed at 62˚.

● Ritchtrabeculoplasty lens has two mirrors at 59˚ and

two at 62˚ with convex lens over the two.

7. Gonioscopic Techniques for Step Iris

Configuration and Narrow Angles

7.1. Manipulative Gonioscopy

Manipulative gonioscopy is useful in studying angle

anatomy in narrow irido-corneal angles. The angle cham-

ber width is initially evaluated in primary gaze followed

by observation of angle by asking patients to look into

mirror with mirror tilted towards angle to be viewed.

7.2. Indentation Gonioscopy

The procedure is done with corneal type gonio-lenses

that have small diameter. The central cornea is indented

to force aqueous out and artificially widen the angle to

view structures that were not visible before indentation.

This was introduced by Forbe’s [9]. The closure of the

angle can be due to following causes:

● Synechial.

● Appositional.

● Optical.

Three things can happen on indentation:

● Iris moves peripherally backwards, assumes a con-

cave configuration and angle recess widens. This re-

presents appositional closure [10].

● Iris moves peripherally backward but periphery of the

iris bulges and does not assume concave configura-

tion. This represents an anteriorly displaced ciliary

body and iris root, seen in plateau iris.

● The iris moves only slightly and evenly backward,

but retains a convex profile. This can occur due to an

anteriorly displaced lens or large diameter lens.

8. Aims and Indications for Gonioscopy

8.1. Diagnostic Uses

● For visualization of anterior chamber angle.

● Evidence of angle closure or narrow peripheral ante-

rior chamber (Van Herricks).

● Classification of glaucoma.

● To look for any abnormality in angle-neovasculariza-

tion angle recession, inflammation, tumor, degenera-

tive ordevelo mental abnormality.

8.2. Therapeutic Uses

● Argon laser trabeculoplasty, selective laser trabecu-

loplasty.

● Goniotomy.

9. Gonioscopic Anatomy

While performing gonioscopy one can identify the struc-

tures from anterior to posterior and vice versa. The angle

structures from anterior to posterior includes cornea,

Schwalbe’s line(termination of descemet’s membrane),

anterior non-pigmented trabecular network, the scleral

spur, the ciliary body band, and the insertion into the

ciliary body.

1) Cornea

Open Access OJOph

Gonioscopy: A Review

120

2) Schwalbe’s line: This is the peripheral termina-

tion of the cornea where the Descemet’s membrane ends.

It can be best identified by locating the corneal wedge.

Prominence of this line is known as posterior embryo-

toxon, seen in Axenfield Reiger’s Anomaly. Pigments

along this line are known as Sampaolesi’s line, seen

in pigmentary glaucoma and pseudo-exfoliation syn-

drome.

3) Trabecular meshwork: This has porous and textured

appearance. Dispersed pigmentation is seen especially

posteriorly which overlies Schlemm canal and is the

functional portion meshwork. Pigmentation is prominent

in inferior and nasal angle.

4) Scleral spur: It is a prominent internal extension of

sclera which is whiter and less translucent compared to

trabecular meshwork.

5) Ciliary body band: It is seen as light grey to dark

brown band.

6) Iris: Following points are to be noted-configuration,

concave, convex and insertion.

Angles in Infants

Normal infants have flat iris inserted posterior to scleral

spur with little pigmentation in trabecular meshwork. A

normal ciliary body band is present. In congenital glau-

coma, the key finding is anterior insertion of iris, directly

in the trabecular with thin ciliary body.

10. Grading of Angle

● Shaffer system.

● Scheie system.

● Spaeth system.

● RPC system.

10.1. Shaffer System

According to the Shaffer system, angle of anterior cham-

ber can be graded as following.

Grade 4 (35˚ - 45˚) Ciliary body

band seen Incapable of closure

Grade 3 (25˚ - 35˚) Scleral spur seen Incapable of closure

Grade 2 (20˚) Trabecular

meshwork seen

Closure possible but

unlikely

Grade 1 (10˚) Schwalbe’s line

seen High risk of closure

Grade S (<10˚) No iridocorneal

contact Imminent closure

Grade O (0˚) No corneal wedge Indentation

gonioscopy

10.2. Scheie System

According to the Shaffer system, grading of angle of

nterior chamber is as following. a

Grade 0 CBB seen No angle closure

Grade I CBB Narrow No angle closure

Grade II CBB not seen, SS

seen Rarely closure possible

Grade III Post. TM not seen Closure likely

Grade IV Schwalbe’s line not

seen Gonioscopically closed

10.3. Spaeth System

This system grades the angle as a combination of fol-

lowing findings:

Iris configuration:

q: Queer (concave peripheral iris).

r: Regularly straight iris.

s: Steeply concave iris.

Angular width: 10˚, 20˚, 30˚, 40˚.

Level of iris insertion:

A: Anterior to schwalbe’s line.

B: Just behind schwalbe’s line.

C: At the scleral spur.

D: Deep angle CBB seen.

E: Extremely deep angle.

Iris process:

U: along angle recess.

V: upto trabecular meshwork.

W: uptoschwalbe’s line.

Pigmentation of posterior trabecular meshwork:

0: No visible pigmentation.

1+: Just perceptible pigmentation.

2+: Definite but mild.

3+: Moderately dense.

4+: Dense black pigmentation.

10.4. RPC System

RPC system of grading of anterior chamber angle is as

following:

Grade 0: Closed.

Grade 1: Schwalbe’s.

Grade 2: Anterior (non-pigmented) TM.

Grade 3: Posterior pigmented TM.

Grade 4: Scleral spur.

Grade 5: Ciliary body band.

Grade 6: Root of Iris.

11. Gonioscopic Findings in Various

Disorders

11.1. Disorders Associated with Open Angle

1) Iris process: Prominent iris processes are feature of

Axenfeld Reiger’s anomaly. Broken iris process are seen

in angle recession [10].

2) Trauma: Angle recession-widening of ciliary body

band.

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Gonioscopy: A Review

Open Access OJOph

121

a) Foreign body in angle.

b) Hyphema in angle.

c) PAS, pigmentation.

3) Pigmentary glaucoma: Sampaolesi’s line.

4) Pseudo exfoliation syndrome: White flaky mate-

rial and pigmentation can be seen.

11.2. Disorders Associated with Closed Angle

1) Angle closure glaucoma shows narrow/closed angle.

Peripheral anterior synechiae and gonio-synechiae may

be present.

2) Mass in angle.

3) Angle blood vessels-neovascular vessels.

11.3. Gonioscopy after Surgery

1) After cataract surgery:

a) Internal aspect of the incision can be seen gonio-

scopically.

b) Pseudophakic chafing by haptic of posterior cham-

ber lens protruding through peripheral iridectomy and

resting in the angle.

2) After filtering surgery:

a) Inner aspect oflimbal fistula and drainage implant

can be seen.

b) Iridectomy can be observed [11].

12. BiometericGonioscopy

This is new method for objective measurement of ante-

rior chamber angle. The reticule ismounted on slit lamp

X10 ocular and ruled in 0.1 mm units, which is used to

measure the distance between insertion of the iris and

Schwalbe’s line in superior, inferior, nasal and temporal

quadrants. If the angle is closed, a measurement of 0 is

recorded, while an occludable angle is defined as one

with an average measurement of 0.25 mm or less for the

four quadrants.

13. Disinfection of the Lens

Guidelines by the American Academy of Ophthalmology

[11]:

● Invert the contact lens.

● Wipe the lens with alcohol sponge.

● Fill concave area with 1:10 solution of household

bleech.

● Leave for five minutes.

● Rinse with water.

14. Conclusion

At present, there are new techniques such as ultrasound

bio microscopy and optical coherence tomography, avail-

able to ophthalmologists for the evaluation of the iri-

docorneal angle. These techniques can describe the width

of the angle and perhaps the risk of developing angle clo-

sure. Though they are excellent tools, they cannot replace

gonioscopy as the basic investigation for the diagnosis of

glaucoma. Gonioscopy not only tells whether the angle is

open or closed but also underlying cause of the same in a

very cost-effective manner. In fact, it would be rational

to state that without reasonable proficiency in the basic

technique of gonioscopy, one should not manage glau-

coma patients.

REFERENCES

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