Gonioscopy

Gonioscopy
Presented by:
Kartik Kumar Gupta
B. Optometry- 2nd year
BV(DU)MC school of optometry, Pune

13-03-2020 Kartik Kumar Gupta 2

1. Schwalbe’s line, 2. Trabecular meshwork, 3.
scleral spur, 4. ciliary body, 5. iris13-03-2020 Kartik Kumar Gupta 8

The Normal Angle
Iris:
• Peripherally, the contour of the iris is usually found to be flat or
slightly convex.
• Hyperopic eyes have more convex irides, while myopic or aphakic
eyes may have slightly concave irides.
• Abnormal convexity is noted in pupillary block, with large lenses,
and with tumours and cysts of the iris and ciliary body, plateau-
iris.
• Abnormal concavity is seen in the pigment dispersion syndrome
and the iris-retraction syndrome.

Iris continued…
• The iris also has concentric contraction rolls, which are most
prominent when the pupil is large and the iris bunched.
• The most peripheral roll of the iris is frequently more
prominent than other contraction rolls.
• In some eyes(e.g.- plateau iris syndrome) this last roll can
obscure visualization of the trabecular meshwork.
• As the angle is approached the stroma of the iris becomes
thinner and smoother.
• There may be a scalloped border where the iris inserts into
the face of the ciliary body.

Ciliary Body Band
• The iris usually inserts into the concave face of the ciliary body,
leaving some of the ciliary body visible anterior to the iris.
• The ciliary body band is seen as a light gray to dark brown band
located just anterior to the iris and posterior to the scleral spur.
• This band can be quite wide in myopic or aphakic eyes and
narrow to absent in hyperopic eyes or eyes with anterior
insertions of the iris.
• If the ciliary body band is abnormally deep and not symmetric
with the other eye, the possibility of angle recession,
cyclodialysis, or unilateral high myopia must be considered.

Scleral Spur
• The scleral spur is a ridge of scleral tissue that lies anterior to
the ciliary body band and marks the posterior border of the
trabecular meshwork.
• Appears as a thin band that is usually white or light gray but
which may have a yellowish cast in older individuals.
• Difficult to distinguish from trabecular meshwork in lightly
pigmented eye.
• Although the scleral spur is usually visible, it may be
obscured by iris processes, a high insertion of the iris, iris
bombe, peripheral anterior synechiae, or heavy
pigmentation.

Trabecular Meshwork
• The trabecular meshwork lies between the scleral spur and
Schwalbe's line.
• The meshwork is nonpigmented and smooth in infants but
becomes coarser and more pigmented with advancing age.
• Pigment in the angle is usually heaviest inferiorly owing to
gravitational settling and aqueous circulation.
• With narrow angles there can be more pigment superiorly than
inferiorly as a result of apposition of the iris against trabecular
meshwork.

Trabecular Meshwork cont’d…
• A non-pigmented angle is a pale gray color .
• Trabecular pigmentation usually appears deep within the
posterior trabecular meshwork.
• Sometimes pigment is deposited on the surface of the posterior
trabecular meshwork or over the anterior trabecular meshwork
and Schwalbe’s line.
• Heavy pigmentation may cover all angle structures.
• Increased pigmentation of the angle can be caused by many
pathological processes.

Trabecular meshwork cont’d…
• Heavy angle pigment can accumulate in a line anterior to
Schwalbe's line as a Sampaolesi's line.
• Sampaolesi's Iine is a non-specific finding in heavily pigmented
angles, whether physiologic or pathologic.
• The extra line of pigment can cause confusion in determining the
location of the pigmented trabecular meshwork.
• The corneal wedge can help in locating Schwalbe's line and in
defining whether the pigmentation is in the trabecular meshwork
or anterior to it.
• The anterior border of the trabecular meshwork is usually
smooth, but it can be wavy and irregular.

Schlemm’s Canal
• In most individuals Schlemm's canal is not visible. It lies deep within
the posterior (pigmented)trabecular meshwork, anterior to the scleral
spur, and becomes visible only when filled with blood.
• Blood can occasionally be found in Schlemm's canal in normal eyes. It
may also be seen in situations where the flow of aqueous humor from
Schlemm's canal to the episcleral venous system is impeded. This can
occur when a contact lens with a large diameter (such as a Goldmann
lens) is pressed too firmly against the eye, compressing the episcleral
veins.
• It can also be seen when the pressure in the episcleral venous system
is high or when the intraocular pressure is low.

Schwalbe’s Line
• Schwalbe's line represents the anterior border of the trabecular
meshwork. It is the termination of Descemet's membrane.
• Schwalbe's line is usually subtle, marked only by a slight change
in color and density from trabecular meshwork to cornea and,
occasionally, by a faint white line.
• The corneal wedge, is invaluable in identifying Schwalbe's line.
• In most eyes the line is a flat transition zone between trabecular
and corneal endothelium.
• Pigment deposited on and anterior to Schwalbe's line is called a
Sampaolesi's line,

GONIOSCOPY
• Gonia means “angle” and skopein means to “observe” in
Greek.
• It is a clinical technique that is used to examine structures in
anterior chamber angle.

Optical Principles:
• The anatomy of the eye is such that the angle recess is not
visualized by routine instrumentation due to total internal
reflection of rays emerging from the angle recess.
• The lens on the cornea has a higher refractive index than the
cornea and the tear fluid and thus eliminates the phenomenon
of total internal reflection.
• In modern gonioscopy contact lenses are used to overcome the
problem of total internal reflection.
• Two basic types of lens are used: the direct Lens and the indirect
lens.

Common Indication For Gonioscopy
• Narrow anterior chamber angles by Van Herick (grade II or narrower).
Gonioscopy is the gold standard technique against which screening
tests for narrow angles are compared (e.g. Johnson & Foster 2005).
• Narrow (or closed) angle glaucoma including evaluation and
documentation of peripheral anterior synechiae if present (Johnson &
Foster 2005).
• Primary open angle glaucoma (POAG) and risk factors for POAG (e.g.
elevated intraocular pressure) to confirm ‘primary’ diagnosis.

Common Indication For Gonioscopy Cont’d…
• Secondary open angle glaucoma and risk factors (e.g. chronic
uveitis, pseudoexfoliation, pigment dispersion) to contribute to
determination of disease severity.
• Risk of angle recession post-blunt trauma.
• Risk of intraocular foreign body.

Common Indication For Gonioscopy Cont’d…
• Congenital or acquired structural irregularities of the iris and
anomalies of the anterior chamber (e.g. iris cysts or tumours,
ectopic pupil).
• Post-laser peripheral iridotomy to assess effect on angle depth.
• Risk of angle neovascularisation (e.g. confirmed rubeosis iridis,
and ischaemic posterior segment conditions including vein or
artery occlusions and diabetic retinopathy; e.g. Browning et al.
1998).

Contraindication Of Gonioscopy
• Recent ocular trauma especially in the presence of hyphaema or
microhyphaema.
• Recent intraocular surgery, including cataract surgery.

Direct Gonioscopy
• Direct gonioscopy is performed with a
steeply convex lens, which permits
light from the angle to exit the eye
closer to the perpendicular at the
interface between the lens and the air.
• These lenses are used with a portable
slit lamp or an operating microscope.

Various Types Of Direct Goniolens
1. Koeppe Goniolens is the most commonly used for
diagnostic direct gonioscopy.
2. Hoskins Barkan’s Lens is a prototype surgical goniolens
used for goniotomy.
3. Swan Jacob’s Lens is also used for surgical purpose.
4. Richardson-Shaffer’s Goniolens is basically small Koeppe
lens used for infants.
5. Sieback Goniolens- it is a tiny goniolens which floats on the
cornea.

Koeppe Lens
• The Koeppe lens, which is a 50-dioptre convex lens, is placed on the
eye of a recumbent patient using saline to bridge the gap between
lens and cornea.
• The examiner views the angle through a hand-held binocular
microscope, which is counterbalanced to permit ease of handling.
• Illumination is provided by a light source that is held in the other
hand.
• The Koeppe lens magnifies x 1.5. This, in combination with the x 16
magnification of the oculars, yields a total magnification of x24.
• Koeppe lenses are manufactured in several sizes to suit infants to
adults.

Advantages Of Direct Gonioscopy
• Greater flexibility because position of observer can be changed.
• Panoramic view is obtained so one part of angle can be
compared with other.
• Angle become deep in supine position so it is easy to see the
angle.
• Cause less distortion of anterior chamber.

Advantages Of Direct Gonioscopy Cont’d…
• Can be used in sedated/anesthetized patients as in infants.
• Provides a straight view rather than inverted view.
• Can be used for surgical procedures like goniotomy.
• Detailed examination of minor structures is possible because the
observer can change his or her height to look deeper into anterior
chamber.

Disadvantages of direct gonioscopy
• Inconvenient
• Annoying light reflex from cornea
• Time consuming
• Benefits of slit lamp (like variable light and better clarity are not
available)

Indirect gonioscopy
• The lenses used in indirect
gonioscopy use mirrors or prism
to overcome total internal
reflection.
• The mirror redirects light from
the angle so that it exits the eye
perpendicularly to the lens-air
interface.
• It uses the slit lamp’s illumination
and magnification system to its
advantages.

Goldmann 3-Mirror Goniolens
• Goldmann three mirror universal lens uses a high minus contact
lens to neutralize the power of the cornea and an appropriate
angled mirrors to allow examination of anterior chamber angle,
peripheral and mid-peripheral fundus as well as a central lens for
the evaluation of the vitreous and the posterior pole.
• The mirror having inclination of 59, 67 and 73 degree is used for
gonioscopy, examine pars plana and ora serrata respectively.

Goldmann Two Mirror Goniolens
• Both the mirror is inclined at 62 degree.
• It needs to be rotated once to examine whole angle.

Goldmann Single Mirror Goniolens
• The mirror is inclined at 62 degree.
• It is prototype diagnostic gonioprism.
• It is to be rotated three times to
examine the whole angle.

Advantages Of Goldmann Goniolens
• Easy to use, excellent view, stabilizes the globe and therefore
can be used for laser trabeculoplasty, peripheral retina can
be seen.
• Better view in patient with significant loss of corneal
transparency.
• Goldmann two mirror gives best in-situ view of the angle.

Disadvantages Of Goldmann Goniolens
• Curvature of lens is more than that of cornea so coupling material is
required. It blurs vision and fundus; therefore, visual field charting,
direct and indirect ophthalmoscopy cannot be done immediately
after its use.
• Only one mirror is there for gonioscopy so it needs to be rotated by
360 degrees.
• It cannot be used for indentation gonioscopy.
• Broad area of contact with cornea is there in case of Goldmann three-
mirror and under pressure it can lead to artefactual closure of angle.

Allen-Thorpe Gonioprism
• It has got four prisms instead of mirrors and allows examination of
the whole angle when rotating prisms.

Zeiss Four-mirror Gonioprism
• It has four identical mirrors angled at 64 degree which allow examination
of four quadrants without rotation of the lens.
• By turning only 11 degree through lens, the smaller area in between the
mirror can be visualize.
• Because the lens has a small (9 mm) area of contact with the cornea, the
angle can be deepened by pushing on the lens.
• The small gap between lens and cornea is filled with tears or topical
anaesthetic.
• This keeps the cornea free of viscous fluids and permits clear examination
and photography of the optic nerve head following gonioscopy.

Posner Gonioprism
• The Posner lens is similar to the Zeiss lens but is made of plastic
instead of glass and also has a fixed, rather than a detachable, handle.

Sussman Lens
• The Sussman lens is also similar to the Zeiss lens, except that it has no
handle.

Van–Herick Technique

THANK YOU

Gonioscopy

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