ANATOMY OF ANTERIOR CHAMBER ANGLE AND GONIOSCOPY.pptx

ANATOMY OF ANTERIOR
CHAMBER ANGLE AND
GONIOSCOPY
BY-
Dr NATASHA PANESAR (PRIMARY DNB)
GUIDE –Dr SHAIFALI KHANDPUR

INDEX
• 1.Structures Forming Anterior Chamber
• 2.Formation Of Anterior Chamber
• 3. Embryology
• 4. Description Of Structures Forming Angle Recess
• 5. Gonioscopy

FORMATION OF ANTERIOR CHAMBER
• The limbus is the transition zone between the cornea and the sclera.
• On the inner surface of the limbus is an indentation: the scleral sulcus, which has
a sharp posterior margin, the scleral spur, and a sloping anterior wall that extends
to the peripheral cornea.
• A sieve- like structure, the trabecular meshwork, bridges the scleral sulcus and
converts it into a tube called the Schlemm canal
• Where the meshwork inserts into the peripheral cornea, a ridge is created,
known as the Schwalbe line.
• The Schlemm canal is connected by intrascleral channels to the episcleral veins.
• The trabecular meshwork, Schlemm canal, and the intrascleral channels make up
the main route of aqueous humor outflow

• The ciliary body attaches to the scleral spur and creates the supraciliary
space ,a potential space between ciliary body and sclera.
• On cross section, the ciliary body has the shape of a right triangle, and the
ciliary processes (the actual site of aqueous humor production) occupy the
innermost and anterior- most portion of this structure in the region called
the pars plicata (or corona ciliaris).
• The pars plicata region is also composed of smooth muscle, which serves
the important functions of accommodation and uveoscleral outflow.
• The ciliary processes consist of 70 to 80 radial ridges (major ciliary
processes), between which are interdigitated an equal number of smaller
ridges (minor or intermediate ciliary processes)

• The posterior portion of the ciliary body, called the pars plana (or
orbicularis ciliaris), has a flat inner surface and joins the choroid at the
ora serrata .
• The anterior–posterior length of the ciliary body in the adult eye
ranges from 4.6 to 5.2 mm nasally to 5.6 to 6.3 mm temporally-75%
by pars plana .
• The iris inserts into the anterior side of the ciliary body, leaving a
variable width of the latter structure visible between the root of iris
and the scleral spur, referred to as the ciliary body band

• The lens is suspended from the ciliary body by zonules and separates
the vitreous posteriorly from the aqueous humor anteriorly.
• The iris separates the aqueous humor compartment into a posterior
and an anterior chamber, and the angle formed by the iris and the
cornea is called the anterior chamber angle
• Normal Angle is 35-45 degrees

Cellular Organization of Ciliary Body and
Ciliary Processes
• The ciliary body is one of the three portions of the uveal tract, or
vascular layer of the eye; the other two structures in this system are
the iris and choroid.
• The ciliary body is composed of muscle, vessels, epithelia lining the
ciliary processes, and nerve terminals from the autonomic nervous
system

CILIARY PROCESSES
• The functional unit responsible for aqueous humor secretion is the
ciliary process, which comprises capillaries, stroma, and epithelia .
The ciliary process capillaries occupy the center of each process.
• The thin endothelium has false “porous” areas of fused plasma
membranes with absent cytoplasm, which may be the site of
increased permeability.
• A basement membrane surrounds the endothelium, and mural cells,
or pericytes, are located within the basement membrane

• A very thin stroma surrounds the capillary networks and separates
them from the epithelial layers.
• The stroma is composed of ground substance, consisting of
mucopolysaccharides, proteins, and plasma solutes (except those of
large molecular size); very few collagen connective tissue fibrils,
especially collagen type III; and migrating cells of connective tissue
and blood origin.

• Two layers of ciliary epithelium surround the stroma, with the apical surfaces of the
two cell layers in apposition to each other.
• The pigmented epithelium has numerous melanin granules in the cytoplasm and an
atypical basement membrane on the stromal side.
• In the nonpigmented epithelium, the basement membrane is composed of
glycoproteins that are immunoreactive for laminin and collagen types I, III, and IV
• This membrane, which faces the aqueous humor, is also called the internal limiting
membrane, and it fuses with the zonules.
• The nonpigmented epithelium stains less intensely than the pigmented layer for
cytokeratin 18 but more so for vimentin, with the predominant distribution in the
crests of the pars plicata and the posterior pars plana. It also stains with antibodies
against S- 100 protein

• Another pair of molecules with restricted expression in the
nonpigmented cells are the water channels aquaporin- 1, which is also
expressed in trabecular meshwork endothelium, and aquaporin- 4.
• In transgenic knockout mice, which do not express these water
channels, IOP is significantly reduced compared within the wild- type
mice, whose water channels are normally expressed.
• The mechanism of IOP lowering is through reduction in decreasing
aqueous humor production, but not in outflow. Although these
genetically modified mice have a phenotype of lower IOP, patients with
aquaporin- 1 mutations have normal IOP.

• A variety of intercellular junctions connect adjacent cells within each
epithelial layer, as well as the apical surfaces of the two layers.
• Such junctions include gap junctions, which are expressed by the
pigmented cells, the nonpigmented cells and the pigmented–
nonpigmented cells, and tight junctions or zonula occludens, which
are expressed between the nonpigmented cells.
• The zonula occludens in the nonpigmented ciliary epithelium are
primarily responsible for creating an effective barrier to intermediate-
and high- molecular- weight substances, such as proteins.

• Tight junctions create a permeability barrier between the nonpigmented
epithelial cells, which forms part of the blood– aqueous barrier.
• These tight junctions are said to be the “leaky” type, in contrast to the
“nonleaky” type in the blood–retinal barrier, and may be the main
diffusional pathways for water and ion flow.
• Microvilli separate the two layers of epithelial cells. In addition, “ciliary
channels” have been described as spaces between the two epithelial layers.
• These channels may be related to the formation of aqueous humor in that
they develop between the fourth and sixth months of gestation,
corresponding to the start of aqueous humor production

• Both sympathetic and parasympathetic nerve endings innervate the
ciliary body.
• The sympathetic fibers synapse in the superior cervical ganglion, and
the postsynaptic fibers are distributed to the ciliary body vessels.
• Because the ciliary epithelium is not innervated, it is thought that the
catecholamine neurotransmitters released from sympathetic nerve
endings diffuse to the adrenergic receptors on the ciliary epithelium.
• Stimulation of these receptors increases aqueous humor secretion by
the ciliary epithelium

• The parasympathetic fibers originate from the Edinger–Westphal
nucleus to innervate the ciliary muscles. Stimulation of these nerve
fibers releases acetylcholine, which then stimulates the cholinergic
receptors on the ciliary muscle.
• These activated receptors cause the ciliary muscle to contract,
causing accommodation by changing the shape of the crystalline lens.
• In addition, ciliary muscle contraction reduces resistance to
conventional aqueous humor outflow, or trabecular outflow, and may
also affect unconventional aqueous humor outflow, or uveoscleral
outflow

EMBRYOLOGY
• Mesenchymal mass of neural crest origin gives rise to cornea ,iris and
anterior chamber angle .
• 3 waves of tissue come forward between surface ectoderm and
developing lens ,from the undifferentiated mesenchymal mass of
neural crest origin .

FIRST WAVE –differentiates into primordial corneal endothelium by 8 rth week and
Subsequently produces Descemet membrane
SECOND WAVE-grows between corneal epithelium and endothelium and produces
Corneal stroma
THIRD WAVE-insinuates between the developing cornea and lens and gives rise to
pupillary membrane and
Stroma of iris

• ANGLE OF ANTERIOR CHAMBER IS OCCUPIED BY A NEST OF LOOSELY
ORGANIZED UNDIFFERENTIATED NEURAL CREST DERIVED
MESENCHYMAL CELLS THAT ARE DESTINED TO DEVELOP INTO THE
TRABECULAR MESHWORK
• It develops by simple growth and differentiation .

• Anterior Chamber Cavity is formed as a slit in the mesenchyme
between the surface ectoderm and developing iris
• The mesenchyme anterior to the slit forms the corneal endothelium
and posterior to the slit forms the primary pupillary membrane

1. Closed cavity of anterior chamber is created by continuous layer of
endothelial cells (derived from neural crest cells ) at 5 th month of
gestation ,
2. Anterior Surface of iris is then inserted in front of primordial
trabecular meshwork
3. Endothelial layer progressively disappears in the third trimester,
from the pupillary membrane and iris and cavities over the anterior
chamber angle (incorporated in the trabecular meshwork )
4. Peripheral uveal tissue begins to slide posteriorly in relation to
chamber angle structure

5. Development of the trabecular lamellar and intratrabecular spaces
begins in the inner posterior aspect of the primordial tissue and
progresses towards developing Schlemm Canal and Schwalbe line
6. Normal Anterior Chamber angle is not fully developed until 1 year
of age

• Schlemm’s canal develops by end of 3rd
month of gestation from
channels derived from mesodermal mesenchyme .
• Posterior Chamber develops as a split in the mesenchyme posterior to
the developing iris and anterior to the developing lens
• The anterior and posterior chambers communicate when pupillary
membrane disappears and pupil is formed .

DESCRIPTION OF STUCTURES FORMING
ANGLE RECESS
1.Ciliary Band –
• It is the most posterior landmark in the angle recess .It is formed by
the anterior most part of the ciliary body between between its
attachment to the scleral spur and insertion of iris.
• Its width depends upon the level of iris insertion ,and tends to be
wider in myopes and narrow in hypermetropes

2.Scleral Spur-
• The posterior wall of the scleral sulcus is formed by a group of fibers,
the scleral roll, which run parallel to the limbus and project inward to
form the scleral spur.
• It is composed of 75% to 80% collagen and 5% elastic tissue.

3.Trabecular Meshwork-
• Scleral sulcus is converted into a circular channel, called the Schlemm
canal, by the trabecular meshwork.
• This tissue consists of a connective tissue core surrounded by
endothelium and may be divided into three portions: (1) uveal
meshwork; (2) corneoscleral meshwork; and (3) juxtacanalicular
tissue, which is also referred to as the cribriform layer .

LAYERS OF TRABECULAR MESHWORK
1. Uveal Meshwork -This innermost portion is adjacent to the aqueous humor in the
anterior chamber and is arranged in bands or ropelike trabeculae that extend from the
iris root and ciliary body to the peripheral cornea. The arrangement of the trabecular
bands creates irregular openings that vary in size from 25 to 75 µm across.
2. Corneoscleral Meshwork -This portion extends from the scleral spur to the anterior
wall of the scleral sulcus and consists of sheets of trabeculae that are perforated by
elliptical openings. These holes become progressively smaller as the trabecular sheets
approach the Schlemm canal, with a diameter range of 5 to 50 µm. The anterior tendons
of the longitudinal ciliary muscle fibers insert on the scleral spur and posterior portion
of the corneoscleral meshwork. This anatomic arrangement suggests an important
mechanical role for the cholinergic innervation of ciliary muscle on trabecular meshwork
function.

• Both the uveal and corneoscleral trabecular bands or sheets are composed
of four concentric layers
1. An inner connective tissue core is composed of typical collagen fibers with
the usual 640 Å periodicity. Central core contains collagen types I and III
and elastin.
2. Elastic fibers are composed of otherwise typical collagen, arranged in a
spiraling pattern with an apparent periodicity of 1000 A .These spiral fibrils
may wind loosely or tightly and may provide flexibility to the trabeculae.
3. Glass membrane is a name given to the layer between the spiraling
collagen and the basement membrane of the endothelium. It is a broad
zone composed of delicate filaments embedded in a ground substance.

4. An outer endothelial layer provides a continuous covering over the
trabeculae.

• The trabecular endothelial cells are larger and more irregular and
have less prominent borders than corneal endothelial cells.
• They are joined by gap junctions and desmosomes, which provide
stability but allow aqueous humor to freely traverse the patent
endothelial clefts.
• Two types of microfilaments have been found in the cytoplasm of
human trabecular endothelium.
• Sixty Å filaments are located primarily in the cell periphery, around
the nucleus, and in cytoplasmic processes.

• These appear to be actin filaments, which are involved in cell
contraction and motility, phagocytosis, pinocytosis, and cell adhesion.
Intermediate filaments of 100 Å are more numerous in the cells and
are composed of vimentin and desmin according to
immunocytochemical studies of cultured human trabecular cells.
• These molecular markers in the trabecular endothelial cells suggest a
myocyte or muscle cell–like phenotype, which further implies
important contractile and motility functions.

3.Juxtacanalicular tissue-
• This structure has three layers, discussed here beginning with the innermost
portion. The inner trabecular endothelial layer is continuous with the endothelium
of the corneoscleral meshwork and considered as a part of this layer.
• The central connective tissue layer has variable thickness and is unfenestrated
with several layers of parallel spindle- shaped cells loosely arranged in a
connective tissue ground substance. This tissue contains collagen type III but no
collagen type I or elastin.
• Connective tissue cells in human trabecular meshwork contain coated pits and
coated vesicles in the plasma membrane, which are involved in receptor-
mediated endocytosis.

• The outermost portion of the trabecular meshwork—that is, the last tissue that aqueous humor
must traverse before entering the canal—is the inner wall endothelium of the Schlemm canal.
• This endothelial layer has significant morphologic characteristics, which distinguish it from the rest
of the endothelium in both the trabecular meshwork and in the Schlemm canal. The surface is
bumpy due to protruding nuclei, cyst like vacuoles, and fingerlike projections bulging into the canal
• The fingerlike projections have been described as endothelial tubules with patent lumens,
although there is lack of agreement as to whether they communicate between the anterior
chamber and Schlemm canal. Actin filaments, as are also present in the inner wall endothelium of
Schlemm canal.
• The intercellular spaces are 150 to 200 Å wide and the adjacent cells are connected by various
intercellular junctions.
• It is not clear as to how tightly these junctions maintain the intercellular connections, although
they will open to permit the passage of red blood cells.

• Zonula occludens are traversed by meandering channels of
extracellular space or slit pores, although it is estimated that this
accounts for only a small fraction of the aqueous humor that leaves
the eye by the conventional route.
• Openings in the inner wall endothelium of the Schlemm canal have
been described, and in general, the openings consist of minute pores
and giant vacuoles that vary in size ranging from 0.5 to 2.0 µm .

4.Schwalbe Line-
• Just anterior to the apical portion of the trabecular meshwork is a
smooth area, which varies in width from 50 to 150 µm and has been
called zone S.
• The anterior border of this zone consists of the transition from
trabecular to corneal endothelium and the thinning and termination
of the Descemet membrane.
• The posterior border is demarcated by a discontinuous elevation,
called the Schwalbe line, which appears to be formed by the oblique
insertion of uveal trabeculae into limbal stroma

• Clusters of secretory cells, called Schwalbe line cells, have been
observed just beneath this ridge and are believed to produce a
phospholipid material that facilitates aqueous humor flow through
the canalicular system.

ANTERIOR CHAMBER
• DEPTH -3 mm
• Contains 0.25 ml of aqueous humor
• Volume -220 micro Liters
• Diameter -11.3 -12.4 mm
• Volume decreases by 0.11 micro liter /year life
• Depth decreases by 0.01 mm/year of life
• Deepens by 0.06 mm for each diopter of myopia
• It is shallower in hypermetropes ,children and older people
• It is slightly diminished during accommodation

GONIOSCOPIC ANATOMY
• The position of the lens and the overlying iris determines the depth of
anterior chamber .
• The width of chamber angle is defined by the point of iris insertion on
the ciliary body ,the peripheral contour of iris as it drapes around the
lens and the pupillary size .
• The deep chambered eye has a wide angle whereas the contour of
shallow chambered eye tends to be narrow .
• Angle formed between the iris and surface of trabecular meshwork is
between 20 and 45 degrees ,the eye is said to have a wide angle .
• Angles smaller than 20 are termed as narrow angles

• PLATEAU IRIS –Peripheral iris is displaced anteriorly into the angle by
anomalously positioned and rotated ciliary processes behind the root
(demonstrated by UBM) ,pupillary dilation may bunch up the iris and
occlude the angle appearing as a sine wave configuration .This angle
remains unchanged after surgery .

GONIOSCOPY
• It is best to start gonioscopy by looking at pupil for rapid orientation
• The anterior lens surface of lens can be observed for focal
opacifications (Glaukomoflecken) of anterior lens and for posterior
synechiae and also dandruff like flecks of exfoliation on the pigment
at the posterior edge of pupil seen in exfoliation syndrome .
• Iridodonesis can be seen in deep chambered eyes

Contour of iris –noting its flatness when deep and its convexity with shallow anterior
chamber and peripheral concavity in cases of high myopia and pigment dispersion syndrome
Site of Iris Insertion –both apparent and actual juncture of angle ,best judged by indentation
gonioscopy
1. At the level of upper trabecular meshwork and Schwalbe’s line
2.Just below the scleral spur
3.Below the spur in the ciliary body
4.Deep posteriorly in the ciliary band
Angulation between iris insertion and slope of inner cornea in the angle in approximate steps
of 10 degrees
Abnormalities such as neovascularization ,hypoplasia ,atrophy and polycoria should be noted

HISTORICAL BACKGROUND
• In 1907, Trantas visualized the angle in an eye with keratoglobus by
indenting the limbus. He later coined the term gonioscopy.
• Salzmann introduced the goniolens in 1914, and Koeppe improved on
it 5 years later by designing a steeper lens.
• Troncoso also contributed to gonioscopy by developing the
gonioscope for magnification and illumination of the angle.
• In 1938, Goldmann introduced the gonioprism, and Barkan
established the use of gonioscopy in the management of glaucoma.

PRINCIPLE OF GONIOSCOPY
• In healthy eyes, the angle cannot be visualized directly because of the
optical principle known as the critical angle.
• The critical angle is related to the properties of light passing through
media with different indices of refraction.
• When light passes from a medium with a greater index of refraction to
one with a lesser index, the angle of refraction (r) is larger than the
angle of incidence (i).
• When r equals 90 degrees, i is said to have attained the critical angle.
• When I exceeds the critical angle the light is reflected back into the first
medium.

• The critical angle for the cornea–air interface is approximately 46
degrees.
• Light rays coming from the anterior chamber angle exceed this critical
angle and are therefore reflected back into the anterior chamber,
preventing direct visualization of the angle.
• The solution to this problem is to eliminate the cornea–air interface
by using a goniolens or gonioprism.
• Because the index of refraction of a contact lens approaches that of
the cornea, there is minimal refraction at the interface of these two
media, which eliminates the optical effect of the front corneal surface

• Therefore, light rays from the anterior chamber angle enter the
contact lens and are then made to pass through the new contact
lens–air interface by one of two basic designs:-
A. DIRECT GONIOSCOPY
B. INDIRECT GONIOSCOPY

DIRECT GONIOSCOPY
1.INSTRUMENTS –
• The Koeppe lens is the prototype diagnostic goniolens, particularly for
children, and is available in different diameters and radii of posterior
curvature.
• A gonioscope, or handheld slit lamp, provides 15× to 20×
magnification.
• The light source may be a separate handheld unit, such as the Barkan
focal illuminator, although it may be attached to the gonioscope or
included in the slit lamp.

2.TECHNIQUE
• Direct gonioscopy is performed with the patient in a supine position,
preferably on a movable diagnostic table or chair.
• After applying a topical anesthetic, the gonio lens is positioned on the cornea,
with either balanced salt solution or a viscous preparation such as
methylcellulose serving as a coupling agent between the gonio lens and the
patient’s cornea.
• The examiner holds the portable slit lamp or may use a gonioscope in one
hand and a light source in the other hand .
• In either case, the examiner scans the anterior chamber angle by shifting his
or her position until all 360 degrees have been studied.

DIRECT GONIOSCOPY GONIOLENSES
LENS DESCRIPTION /USE
Koeppe Prototype diagnostic goniolens
Richardson– Shaffer Small Koeppe lens for use in infants
Layden For gonioscopic examination of premature infants
Barkan Prototype surgical goniolens
Thorpe Surgical and diagnostic lens for operating rooms
Swan Jacob Surgical goniolens for use in children

INDIRECT GONIOSCOPY
1.INSTRUMENTS
• The gonioprism and a slitlamp are the only instruments needed for indirect
gonioscopy. Several types of goniolenses are available with a single mirror or
multiple mirrors.
• The Goldmann single- mirror lens is tilted 62 degrees from the plano front
surface, which allows examination of the anterior chamber angle.
• The Goldmann three- mirror lens contains two mirrors for examination of the
fundus, and one for examination of the angle.
• Because of their 7.38- mm posterior radius of curvature, both Goldmann
lenses require the use of a viscous material to fill the space between the
cornea and the lens.

• In contrast, a modified Goldmann- type lens, with its 8.4 mm radius of
curvature, requires no viscous bridge.
• Goldmann type lenses have also been modified with antireflection
coating, allowing them to be used for laser trabeculoplasty.
• In the Zeiss four- mirror lens, all the mirrors are tilted at 64 degrees
for evaluation of the angle, eliminating the need to rotate the lens.
• The original four- mirror lens is mounted on a holding fork (an Unger
holder), whereas newer models have a permanently attached holding
rod (a Posner lens) or are held directly, such as Sussman-style lenses

• The posterior curvature of these four- mirror lenses is similar to that of
the cornea.
• Before placement of these lenses on the eye, a drop of proparacaine
may be placed on the lens to serve as a coupling agent.
• With the Goldmann- and Zeiss- type instruments, the anterior chamber
angle is viewed “indirectly” through a mirror 180 degrees from the
quadrant being viewed .
• Some newer gonioprisms enable direct viewing of the angle.
• More recent indirect gonioscopy options include six mirror lenses such
as the Volk G- 6 gonioscopy lens

INDIRECT GONIOSCOPY GONIOLENSES
LENS DESCRIPTION
Goldmann single mirror Mirror inclined at 62 degrees for gonioscopy
Goldmann three- mirror One mirror for gonioscopy, two for retina; coated
front surface available for laser use
Zeiss four- - mirror All four mirrors inclined at 64 degrees for
gonioscopy; requires holder (Unger); fluid bridge not
required
Posner four- - mirror Modified Zeiss four- mirror gonioprism with a
Sussman four- - mirror Handheld Zeiss- type gonioprism
Thorpe four- - mirror Four gonioscopy mirrors, inclined at 62 degrees
requires fluid bridge
Ritch trabeculoplasty lens Four gonioscopy mirrors, two inclined at 59 degrees
and two at 62 degrees, with convex lens over two

LENS DESCRIPTION
Latina trabeculoplasty lens One mirror for trabeculoplasty
Volk G- 6 Six gonioscopy mirrors, inclined at 63 degrees

2.TECHNIQUE
• The cornea is anesthetized and the patient is positioned at the slit lamp.
• A drop of proparacaine is placed on the gonioprism. The gonioprism is then
gently placed against the cornea.
• The light beam parameters may be about 2 mm, with a width of roughly 0.5
mm.
• The beam is fixated on a mirror, and then the slit lamp joystick is rotated to the
other quadrant mirrors to allow visualization of all 360 degrees of the angle.
• Visualization into a narrow angle can be enhanced by manipulating the
gonioprism—for example, asking the patient to look in the direction of the
mirror being used.

INTRAOPERATIVE GONIOSCOPY
• There has been a rise in the number of angle- based microinvasive
glaucoma surgeries that require visualization of the angle
intraoperatively.
• With this, there has been a need for intraoperative gonioscopy lenses
that allow for sufficient visualization without impeding surgical access.
• To obtain optimal visualization, both the patient’s head and the
microscope are tilted.
• The patient’s head is lifted and turned about 30 degrees away from
the surgeon and the microscope is also tilted away the same amount.

• The microscope oculars and surgeon’s chair must also be adjusted to
maintain ergonomics.
• A viscoelastic coupling agent may be applied to the cornea for lubrication.
• One commonly used lens is the modified Swan Jacob lens. Other lenses
like the Khaw, Ritch, Hill, and Vold are also available and similar to the
modified Swan Jacob lens.
• Another lens is the Ahmed 1.5× Surgical Goniolens, which is an indirect
gonioscopy lens that offers 1.5- fold magnification of angle structures.
• Endoscopic probes or high- resolution camera systems like the EyeCam
may be used to visualize the angle intraoperatively as well.

CLEANING OF DIAGNOSTIC CONTACT LENSES
• Any instrument that contacts the eye creates the potential hazard of transmitting bacterial
and viral infections.
• Adenovirus type 8 can be removed or inactivated by soaking the mirror for 5 to 15 minutes
in diluted sodium hypochlorite (1:10 household bleach), 3% hydrogen peroxide, or 70%
isopropyl alcohol, or by wiping with alcohol, hydrogen peroxide, iodophor (povidone-
iodine), or 1:1000 Merthiolate.
• Herpes simplex virus type 1 was eliminated by swabbing the mirror with 70% isopropyl
alcohol.
• Wiping with 3% hydrogen peroxide or 70% isopropyl alcohol swabs completely disinfected
tonometer tips contaminated with HIV- 1
• With any technique, it is important to carefully remove the disinfectant from the contact
surface before the next use using a tissue, because alcohol and hydrogen peroxide each can
cause transient corneal defects or even abrasions

GONIOSCOPIC APPEARANCE OF NORMAL
ANTERIOR CHAMBER ANGLE
• Starting at the root of the iris and progressing
anteriorly toward the cornea, the following
structures can be identified by gonioscopy in
an adult with a normal angle

CILIARY BODY BAND IRIS PROCESSES AND
SYNECHIAE
• The ciliary body band is the portion of ciliary body visible in the
anterior chamber as a result of the iris insertion into the ciliary body.
• The width of the band depends on the level of iris insertion and tends
to be wider in myopic eyes and narrower in hyperopic eyes. The color
of the band is usually gray or dark brown.
• If there is no pigment in the trabecular meshwork ,the ciliary body will
be the only pigmented structure in the angle wall .
• In angle recession the ciliary body may be broadly exposed. Irregular,
thread-like fibers of the anterior iris stroma sometimes arborize
across the angle recess and are called iris processes

• Larger processes represent an incomplete embryologic separation of
the iris from the angle wall, which is seen in exaggerated form in the
pathologic congenital syndrome of Axenfeld.
• In blue eyes, the iris processes are light gray and difficult to see, but in
brown eyes, the pigmented processes stand out prominently against
the light background of the scleral spur.
• True synechiae are formed when the peripheral iris becomes attached
to the trabecular wall.

• Some clues for distinguishing iris processes from peripheral anterior synechiae are –
Iris processes are fibers or syncytial sheets that closely follow or bridge the concavity of the
angle recess and that usually allow a view of the angle recess behind them unless they are
extraordinarily dense.
Peripheral anterior synechiae are actual adhesions of iris tissue that cover and occlude variable
amounts of the angle. They can insert low at the level of the scleral spur (such as after laser
trabeculoplasty) to as high as Schwalbe’s line and beyond (as with the irido-corneo-e
ndothelial
syndromes)
Synechiae can form only when the iris is pushed against the trabecular meshwork, as in angle
closure glaucoma, or when the iris is pulled up onto the meshwork as the result of the shrinkage
of inflammatory products or fibrovascular membranes attached to both iris and meshwork. In the
area of a synechia, peripheral iris tissue butts flat against the trabecular surface; it does not wrap
around the angle recess as does an iris process – a distinction well appreciated during
indentation gonioscopy.

SCLERAL SPUR
• This is the posterior lip of the scleral sulcus, which is attached to the
ciliary body posteriorly and the corneoscleral meshwork anteriorly.
• It is usually seen as a prominent white line between the ciliary body
band and functional trabecular meshwork, unless it is obscured by
dense uveal meshwork or excessive pigment dispersion.
• Variable numbers of fine, pigmented strands may frequently be seen
crossing the scleral spur from the iris root to the functional
meshwork.
• These are referred to as iris processes and represent thickenings of
the posterior uveal meshwork.

• The spur’s crisp white appearance is the most helpful landmark in
orienting the gonioscopist.
• It is also prominent in ultrasonic biomicroscopy because unlike other
angle structures such as the posterior trabecular meshwork, it can be
readily identified and thus used as an important landmark in
quantifying angle measurements.

FUNCTIONAL TRABECULAR MESHWORK
• This is seen as a pigmented band just anterior to the scleral spur.
Although the trabecular meshwork actually extends from the iris root
to Schwalbe line, it may be considered in two portions:
(1) the anterior part, between the Schwalbe line and the anterior edge
of the Schlemm canal, which is involved to a lesser degree in aqueous
outflow, and
(2) the posterior pigmented (or functional) part, which is the remainder
of the meshwork and is the primary site of aqueous outflow (especially
that portion immediately adjacent to the Schlemm canal)

• The appearance of the functional meshwork varies considerably
depending on the amount and distribution of pigment deposition.
• The trabecular meshwork has no pigment at birth, but with age, color
develops, from faint tan to dark brown, depending on the degree of
pigment dispersion in the anterior chamber.
• The distribution of pigment may be homogeneous for 360 degrees in
some eyes and irregular in others.
• In the functional portion of the meshwork, especially when lightly
pigmented, blood reflux in the Schlemm canal may sometimes be
seen as a red band.

• In aging and disease processes, the aqueous flow carries pigment from
the iris and deposits it in varying amounts and depths in the meshwork,
giving rise to the trabecular pigment band, which tends to be denser in
the lower angle.
• Such pigmentation can be homogenous in appearance (as in the pigment
dispersion syndrome) or variegated (as seen after anterior segment
trauma).
• The presence and extent of trabecular pigmentation may provide
valuable clinical information, such as suggesting an occult case of
pseudoexfoliative syndrome or being indicative of a favorable response to
laser trabeculoplasty

SCHWALBE LINE
• The Schwalbe line is the junction between the anterior chamber angle structures and
the cornea. It is a fine ridge just anterior to the meshwork and is often identified by a
small buildup of pigment, especially inferiorly.
• By using a thin slit beam at a slightly oblique angle, this line can be identified by the
corneal wedge created by light wedge created at the junction between the inner light
beam along the cornea endothelium and the outer light beam along the corneoscleral
junction.
• It marks the most anterior extension of the meshwork and the termination of
Descemet’s membrane of the cornea.
• Schwalbe’s line is seen as a translucent or white ledge that projects slightly into the
anterior chamber ,or it may be a vague line of demarcation between the smooth surface
of Descemet’s membrane that covers the inner cornea and the less transparent rough
texture of the uveal meshwork.

• The corneal radius of curvature changes to the larger radius of the
sclera,
• This change in curvature and the beginning roughness of the
trabecular surface provide a lodging place for the pigment granules
that may be carried into the inferior angle by the aqueous convection
currents (Sampaolesi’s line).
• Such pigmentation is rare in healthy young eyes but becomes
increasingly common in older or diseased eyes.

NORMAL BLOOD VESSELS
• Blood vessels are normally not seen in the angle, although loops from
the major arterial circle may appear in front of the ciliary body band
and less commonly over the scleral spur and trabecular meshwork.
These vessels typically take a circumferential route in the angle.
• In addition, an anterior ciliary artery may occasionally be seen as a
more radially oriented vessel in the ciliary body band of lightly
pigmented eyes. Circumferential and radial vessels may also
occasionally be seen in the peripheral iris of lightly colored eyes.
• Radial vessels is more common in the peripheral iris, whereas the
circumferential type is more common on the ciliary body band

RECORDING GONIOSCOPIC FINDINGS
• Various classification systems have been suggested for describing the
width and appearance of the anterior chamber angle, including the
Scheie, Shaffer, and Spaeth systems and RPC Grading System .

• The Spaeth grading system uses an intricate alphanumeric scale, attempting to
provide three-dimensional specificity to gonioscopic description. It addresses
each of the following items in sequential order:
(1) The site of insertion of the iris root in the eyewall;
(2) The width or geometric angle of the iris insertion;
(3) The contour of the peripheral iris near the angle;
(4) The intensity of the trabecular pigmentation, and
(5) The presence or absence of abnormalities such as mid-iris bowing, peripheral
synechiae, and so on. If there is a discrepancy between the apparent and the
actual site of iris insertion, as determined by indentation gonioscopy, this is
also noted.

STEP 1-SITE OF IRIS INSERTION
• A = Anterior to trabecular meshwork (i.e., Schwalbe’s line)
• B =Behind Schwalbe’s line (i.e., at level of trabecular meshwork)
• C =Centered at the level of the scleral spur
• D = Deep to the scleral spur (i.e., anterior ciliary body)
• E = Extremely deep in the ciliary body

STEP-2 ANGLE WIDTH
• The geometric angle is estimated at the perceived intersection of the
imaginary tangents formed by the peripheral third of the iris and the
inner wall of the corneoscleral junction.
• Though some examiners prefer increments of 10°, as with the Shaffer
system, and others use increments of 15°, these clinical assessments
tend to overestimate by 5° the actual angle, as measured by the
ultrasonic biomicroscope.

STEP-3 IRIS CONFIGURATION
The newer system describes four iris configurations, indicated by the
first letter of their description:
• b =‘bows 1 to 4 plus’ (usually indicative of optically-appearing closure,
altering with indentation)
• p = ‘plateau’ (comparable to older ‘s’ designation)
• f =‘f lat approach’: the commonest iris appearance (comparable to the
older ‘r’ designation)
• c = ‘concave’ as in posteriorly bowed iris (comparable to the older ‘q’
designation).

STEP-4 TRABECULAR MESHWORK
PIGMENTATION
• The degree of trabecular meshwork pigmentation (TMP) is labeled
from 1 to 4: minimal or no pigment is graded 1, and dense pigment
deposition is indicated as grade 4, with lesser degrees between.

USES OF GONIOSCOPY
• 1. Aid in Diagnosis of Glaucoma .
• 2.Evaluation Of symptoms -halos around lights, which suggests
episodes of angle-closure glaucoma if the angles are found to be
critically narrowed. If the angles are wide open, however, the risk of
sudden, catastrophic tension elevation by angle closure is virtually
non-existent, and the history of halos warrants another explanation.
Appreciation of the signs of pigment dispersion syndrome, such as
Krukenberg’s spindle, iris transillumination defects, and heavily
pigmented trabecular meshwork, can explain sudden episodes of
visual disturbance from ‘pigment storms’ following intense activity

• 3.Use Of Drugs -If an angle is found to be wide open, it is safe to use
strong miotics, mydriatics, or sympathomimetics freely. Such use
might cause the angle to close completely in eyes with narrow angles,
precipitating an acute rise of IOP. If miotics become necessary for the
management of glaucoma in an eye with a narrow angle, the angle
should be re-evaluated after therapy has begun.

• 4. Postoperative Examination –
The success of iridotomy in opening an angle and of cyclodialysis in
producing a suprachoroidal cleft can be evaluated promptly. After
filtering procedures, the surgical stoma can be seen gonioscopically.
If filtration is impaired, the appreciation of a patent ostium will direct
attempts to restore the bleb by addressing the episcleral surface –
suture lysis, bleb needling, or resections of scar tissue beneath the
conjunctiva. If the ostium is occluded by the iris or adhesions, it may be
re-opened using laser.

• 5.Conditions other than glaucoma
The diagnosis of peripheral tumors or cysts often can be made by gonioscopy.
Operability can be determined by an accurate view of the extent to which the iris and
ciliary body are involved, supplemented by anterior segment imaging with UBM.
Foreign bodies in the angle and holes in the peripheral iris from penetrating foreign bodies
may be discovered.
Inflammatory and traumatic conditions, such as keratic precipitates covering the
meshwork and iridodialysis, can be visually evaluated.
When a portion of the cornea is hazy, it may be possible by gonioscopy to look through a
clear portion of cornea to see the reason for the haze.
Tears in Descemet’s membrane, epithelial downgrowth, and areas of vitreous adhesions
can be diagnosed in this way.

INDENTATION GONIOSCOPY
• By deliberately varying the amount of pressure applied to the cornea
with a tear-coupled indirect (e.g., Zeiss) contact lens, the physician
can observe the effects on angle width.
• Increased pressure indents the central cornea and displaces fluid into
the angle, opening it wider .
• To the experienced examiner, this technique is valuable in evaluating
the status of the angle and the presence of synechiae.
• The ability to visualize angle structures by indentation may be
reduced in the presence of elevated intraocular pressure

ANATOMY OF ANTERIOR CHAMBER ANGLE AND GONIOSCOPY.pptx

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