angle of anterior chamber

1. Moderator: Dr. Deepika M
Presenter: K. Sahithi Reddy
2K14, KAMS&RC
ANGLE OF ANTERIOR
CHAMBER
Date: 10-07-2017

2. INDEX :
• Anterior Chamber
• Angle of anterior chamber
• Development
• Aqueous outflow system
• Importance of Angle of anterior
chamber
• Diagnostic modalities

3. ANTERIOR CHAMBER :
• Anterior chamber is an angular
space.
• It is the space formed
Anteriorly by the posterior
surface of cornea
Posteriorly by the lens within
the pupillary aperture, anterior
surface of iris and a part of cilary
body

4. • Anterior chamber Is 3mm deep
and it contains 0.25ml of
aqueous humour.
• Anterior chamber depth is
shallower in the hypermetropic
eye than the myopic eye.
• It is also shallower in children
and older people.
• Chamber depth decreases by
0.01mm/year of life

5. • Chamber depth is slightly diminished during accommodation, partly
by increased lens curvature and partly by forward translocation of
lens.
• Chamber deepens by 0.06mm for each diopter of myopia.

6. • 1. Schwalbe’s line
• 2. Trabecular Meshwork
• 3. Scleral spur
• 4. Anterior most part of ciliary body
• 5. Root of Iris

7. Development :
By 7th week, angle is occupied by mesenchymal cells from neural
crest cells to develop trabecular meshwork.
 In posterior aspect, iris is formed from advancing bilayered optic cup
Corneal endothelium meets derivative of iris at 15th week to
demarcate the angle.
 Angle deepening continues even after birth.

8. Schwalbe’s Line:
• This marks the anterior border
of angle and represents
termination of descemet’s
membrane.
• Seen as glistening white line in
gonioscopy.

9. • Prominance of Schwalbe’s line is known as posterior embryotoxon,
seen in Axenfield Reiger’s Anomaly.

10. Pigments along Schwalbe’s line are known as
Sampaolesi’s line, seen in pigmentary glaucoma &
pseudoexfoliation Syndrome.

11. • Schwalbe’s line marks transition
from
Trabecular to cornea
endothelium.
Termination of the Decemet’s
membrane.
Insertion of trabecular meshwork
into corneal stroma.

12. TRABECULAR MESHWORK:
• It is a sieve like structure made
up of connective tissue lined by
trabeculocytes, which have
contractile and phagocytic
properties.
• Its main function is in drainage
of aqueous humour.

13. • The meshwork is roughly triangular in cross section;
• Apex is at the Schwalbe’s line
• Base is formed by the scleral spur and ciliary body.

14. • It is morphologically and
functionally divided into 3 types :
1. Uveal meshwork
2. Corneoscleral meshwork
3. Juxtacanalicular
tissue/meshwork

15. 1. UVEAL MESHWORK:
• Innermost part of TM
• It comprises of trabecular bands, which have a
central core that mainly consists of collagenous
fibers distributed with a few elastic fibers, and is
lined by trabecular endothelial cells resting on a
thick basement membrane
• The trabecular bands run mostly in radial fashion
• Trabecular apertures size is 25-75 micrometer.
• The trabeculocytes usually contain pigment
granules.

16. 2. THE CORNEOSCLERAL MESHWORK:
• Consists of a series of thin, flat, perforated
connective tissue sheets arranged in a
laminar pattern
• The central core consists of collagenous
and elastic fibres
• Each trabecular beam is covered by a
monolayer of trabecular endothelial cells,
supported by basement membrane.
• The pore size is smaller than the uveal
meshwork (5-50micro metre)

17. Ultrastructure of Meshwork:
• Both uveal and corneoscleral bands are composed of 4 concentric layers
1. An inner connective issue core is composed of collagen fibres, with 64nm
periodicity. The central core contains collagen types I and III and elastin.
2. Elastic fibres are arranged in a spiraling pattern with periodicity of
100nm.

18. 3. Cortical zone also called as glassy membrane
4. An outer endothelial layer provides a continuous covering over the
trabeculae.

19. TRABECULAR ENDOTHELIAL CELLS
• Larger, more irregular and have less prominent borders than corneal
endothelium.
• Joined by gap junction and desmosomes, which provide stability.
• 2 types of microfilaments:
1. Actin filaments : cell periphery, around nucleus, cytoplasmic
processes.
Cell contraction, phagocytosis, pinocytosis and cell adhesions.
Regulating the shape and cytoskeletal organization.

20. • 2. Intermediate filaments:
Numerous, composed of
vimentin and desmin.
Imparts the contractile and
motility functions.

21. 3. JUXTACANALICULAR MESHWORK:
• Also known as cribriform meshwork
• The outermost part of TM
• Lies adjacent to the inner wall of Schlemm’s
canal
• It consists of a lose network of fine fibrils,
elastic like fibres and elongated fibroblasts
life cells and ground substance full of
glycosaminoglycans and glycoproteins
• The spaces between cells are upto
10micrometre.

22. SCHLEMM’S CANAL
• Schlemm’s canal is a circular lymphatic like
vessel in the eye that collects aqueous humour
from the anterior chamber and delivers it into
the episcleral blood vessels via aqueous veins.
• Schlemm’s canal is often divided into different
parts by bridges or septa. The septa cross the
lumen of the canal mostly in an oblique
direction. They are often fixed to the outer wall
of the canal at places where the collector
channels begin.
• The structure of the outer wall of schlemm’s
canal differs very much from that of the inner
wall.

24. INNER WALL OF SCHLEMM’S CANAL
• The endothelial lining of the canal
consists of a complete monolayer of
flat endothelial cells that do not rest
on a complete basement membrane.
• The subendothelial cell layer is not
complete and consists of elongated,
star like cells oriented predominantly
in a radial anteroposterior direction
• The lateral walls of the endothelial
cells are joined by tight junctions

25. • Micropinocytotic vesicles are present at the apical and basal surfaces
of the cells
• Some “vacuoles’’ have openings on the inner and outer sides, thus
forming transcellular microchannels.

26. OUTER WALL OF SCHLEMM’S CANAL
• The endothelial lining is single-
layered, with a well developed
basement membrane
• The cells do not possess
transcellular microchannels.
• The adjacent stroma consists of
collagenous and elastic like
fibers intermingled with
fibroblasts.

27. COLLECTOR CHANNELS
• Schlemm’s canal is connected to
episcleral and conjunctival veins
by a complex system of
intrascleral channels.
• Two systems of intrascleral
channels have been identified:
(a) Indirect system
(b) Direct system

28. (a) INDIRECT SYSTEM
• Indirect system consists of 15-
20, finner channels, which form
an intrascleral plexus before
eventually draining into the
episcleral venous system

29. (b) DIRECT SYSTEM:
• Direct system consists of large
caliber vessels, which run a short
intrascleral course and drain
directly into the episcleral
venous system, they are about
6-8 in number and also called as
aqueous veins.
• These aqueous vessels terminate
into the episcleral and
conjunctival veins in laminated
junction- it is called LAMINATED
VEIN OF GOLDMANN

30. EPISCLERAL AND CONJUNCTIVAL VEINS
• Most aqueous vessel are
directed posteriorly, with most
of these draining into episcleral
veins, whereas a few cross the
subconjunctival tissue and drain
into conjunctival veins

31. • The episcleral veins drain into
the cavernous sinus via the
anterior ciliary and superior
ophthalmic veins,
• While the conjunctival veins
drain into superior ophthalmic
or facial veins via the palpebral
and angular veins

32. SCLERAL SPUR:
• Wedge shaped circular ridge.
• Pale, translucent narrow strip of
scleral tissue.
• Scleral spur is composed of a
group of fibres known as “scleral
roll”
• Scleral roll is composed of 75-
85% collagen and 5% elastic
tissue.

33. • ATTACHED:
Anteriorly: trabecular
meshwork
Posteriorly: sclera and
longitudinal fibers of ciliary
muscle

34. • Contraction of longitudinal ciliary
muscle opens up trabecular spaces.
• Scleral spur prevents ciliary muscle from
causing Schlemm’s canal to collapse.
• Individual scleral spur cells are
innervated by unmyelinated axons.
• Varicose axons characteristic of
mechano-receptor nerve measure stress
in the scleral spur due to ciliary muscle
contraction or changes in IOP.

35. CILIARY BAND:
• It marks the posterior most part
of the angle.
• Represents the anterior face of
ciliary body between its
attachment to the scleral spur
and insertion of iris.
• Width depends on the level of
iris insertion.
• Wide in myopes
• Narrow in hypermetropes.

36. • Ciliary band appears as a
grey/dark brown band.
• It consists of longitudinal fibres.
• The contraction of longitudinal
muscle, opens the trabecular
meshwork and schlemm’s canal.

37. INNERVATION:
• Derives from the supraciliary nerve plexus and the ciliary
plexus in the region of scleral spur.
• Both sympathetic adrenergic and parasympathetic and
sensory innervation – present

38. Nerve endings contain mechanoreceptors which are
located in scleral spur :
act as proprioceptive tendon organs for the ciliary
muscle,
 contraction myofibroblast scleral spur cells
 baroreceptor function in response to change in IOP

39. IMPORTANCE OF ANGLE OF ANTERIOR CHAMBER:
• For classification of glaucoma
• To note the extent of neovascularization
• To assess angle recession
• History or evidence of inflammation
• For evidence of neoplastic activity
• Degenerative or developmental anomaly
• For planning of treatment – iris neovascularization and
laser procedure.

40. DIAGNOSTIC MODALITIES:
1) Van-herick test
2) Flashlight/ pentorch test
3) Ultrasound biomicroscopy
4) Optical coherence tomography
(OCT)
5) Gonioscopy

41. 1) VAN-HERICK TEST:
• It is a slit lamp estimation of angle
• To perform this test, slit lamp is made very bright and thin. It is
offset 600 temporally to the slit lamp oculars. The temporal sclera
is illuminated and the slit lamp beam is brought slowly towards
the cornea until the anterior chamber is first identified. The
thickness of the cornea is compared to the depth of the
peripheral anterior chamber
• At, present, this test is most widely adopted method for
evaluating the ACA in community optometric practice.

42. Corneal thickness: Chamber depth

43. GRADING:

44. 2) PENTORCH EXAMINATION:
• Depth of anterior chamber can be evaluated by focusing a beam of
light on the temporal limbus, parallel to the surface of iris.
• In normal or deep AC the beam will pass through directly, illuminating
the opposite limbus.
• In shallow AC, the anterior placement of or bowing forward of the iris
obstruct the light and shadow is observed on the medial half of iris.

45. 3) ULTRASOUND BIOMICROSCOPY:
• UBM is a close contact (non-invasive) immersion technique.
• UBM is performed with the patient supine, positioning that
theoretically causes the iris diaphragm to fall back. This deepens the
anterior chamber and opens the angle.
• With UBM, only 1 quadrant can be imaged at a time.
• There is a risk of infection or corneal abrasion due to the contact
nature of the examination.

47. O
4) OPTICAL COHERENCE
TOMOGRAPHY(OCT)
• OCT is a non contact, non invasive light
based imaging modality.
• Provides image resolution higher than
that of UBM of anterior segment in
cross section with AS-OCT, 4 quadrants
can be scanned at once(multiple cross-
sectional image of the anterior
chamber angle)
• The working principle of OCT is similar
to ultrasound which uses echoes to
locate structures within the body.

48. 5) GONIOSCOPY:
• Gonioscopy is an essential diagnostic tool and examination technique
used to visualize the structures of the anterior chamber angle.
• All gonioscopy lenses eliminate the tear-air interface by placing a
plastic or glass surface adjacent to the front of the eye.
• Methods of gonioscopy:
1) Direct
2) Indirect

49. DIRECT GONIOSCOPY: Procedure
• Direct gonioscopy is most easily performed with the patient supine
and in the operating room for an examination under anesthesia with
4% xylocaine.
• It is performed using a direct goniolens and either a binocular
microscope or a slit-pen light.
• The lens is positioned after saline or viscoelastic is placed on the eye,
which can act as a coupling device.
• The lens provides direct visualization of the chamber angle in an erect
position

50. DIRECT GONIOSCOPY:
• Direct goniolenses:
Koeppe Barkan
Swan-Jacob

51. KOEPPE LENS:
• Koeppe lens is the prototypical diagnostic
goniolens
• Koeppe gonioscopy is an unsurpassed
method for viewing the chamber angle in
the operating room.

52. • Koeppe-type lenses are also quite useful for performing funduscopy.
• When used with a direct ophthalmoscope and a high-plus-power
lens, they can provide a good view of the fundus, even through a very
small pupil.
• These lenses are especially helpful in individuals with nystagmus or
irregular corneas.
• Inconvenience is the major disadvantage of the direct gonioscopy
systems.

53. • BARKAN’S LENS:
The Barkan goniolens has served as the prototypical
surgical goniolens for surgical goniotomy. Has no rod
• SWAN-JACOB LENS:
The Swan-Jacob goniolens has been modified for
goniosurgery and is now one of the most popular models
for angle surgery.

54. ADVANTAGES- Direct Gonioscopy:
• Observer’s height can be changed to look deep or get a better look at
the angle structure’s
• As it is done in supine position it can be used for sedated, comatosed
patients and in children
• Useful in examining the fundus with small pupil
• Straight on the view
• Panoramic view of the angle structure’s
• Comparison of angle recession
• Causes less distortion of AC

55. DISADVANTAGES:
• Inconvinient
• Special equipment is needed.

56. INDIRECT GONIOSCOPY: Procedure
• Indirect Gonioscopy is performed under the slit lamp.
• The patient and the examiner must be positioned in a comfortable fashion.
• A drop of topical anesthetic is then applied to the conjunctiva of both eyes.
• If using the Goldmann lens, contact gel is placed in the concave part of the
lens.
• If using a Posner or similar type lens, a drop of artificial tears can be placed
on the concave surface.
• The patient is then asked to open both eyes and look upwards.
• The examiner can then pull down slightly on the lower lid and places the
lens on the surface of the eye.

57. • The patient is then asked to look straight ahead.
• Most examiners choose to start with the inferior angle as it is usually
more open, and the pigmentation of the trabecular meshwork is
slightly more prominent, allowing for easier identification of the angle
structures.
• Continue identifying all angle structures in all 4 quadrants, and then
repeat with the other eye.

58. INDIRECT GONIOSCOPY:
• Indirect goniolenses:
Goldmann
Zeiss
Sussman
Posner

59. GOLDMANN LENS:
• It is a three mirror contact lens
• For examination of the entire
ocular fundus and the
iridocorneal angle.
• The advantage of a longer mirror
is that it often permits binocular
observation of the lateral
sections of the ocular fundus

60. OBSERVATION:
• Central lens(1) - Posterior pole
• 730 mirror(2) - Equator
• 670 mirror(3) - Ora serrata
• 590 mirror(4) - Iridocorneal angle

61. ZEISS GONIOLENS:
• 4 identical mirrors angled at 640 which allow
examination without rotation of the lens
• ADVANTAGE: Coupling material not required
as the posterior curvature of the lens is equal t
the corneal curvature
• Easy to perform when mastered
• Indentation gonioscopy can be performed
• DISADVANTAGE: difficult to master
• Does not stabilize the globe

62. •SUSSMAN LENS:
It is similar to Zeiss Lens except that it has no handle
•POSNER LENS:
It is a modified Zeiss Lens with a handle

63. ADVANTAGES- Indirect Gonioscopy:
• Preferred by most
• Quick, convenient
• No special equipment needed
• Slit lamp is used, which provides variable
magnification and illumination
• Can create corneal wedge
• Allows differentiation of appositional and
synechial angle closure

64. DISADVANTAGES:
• Mirror image can be confusing
• Inadvertent pressure on the cornea:
 exaggerates the degree of angle narrowing in the Goldmann lens
 opens the angle in four mirror lenses

65. GRADING SYSTEMS:

68. REFERENCES:
• Glaucoma, 6th edition, Comprehensive Ophthalmology, A K Khurana.
• Gross and Microanatomy of Angle of the Anterior Chamber,
Glaucoma, Volume 1, 3rd edition, Modern Ophthalmology, L C Dutta
and Nitin K Dutta.
• Parsons’ Diseases of the Eye, 22nd edition.
• Shield’s textbook of Glaucoma, 8th edition.