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.
Received January 23rd, 2013; revised February 24th, 2013; accepted March 15th, 2013
Copyright © 2013 Parul Singh et al. This is an open access article distributed under the Creative Commons Attribution License,
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
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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
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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.
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