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1. Aqueous Humor,Anterior
Chamber Angle and its
Examination
Kanwal Perveen Jamali
M.Phil (Vision Sciences)

2. Aqueous Humour
 The aqueous humour is a transparent, clear liquid inside
the front part of the eye. similar to plasma, but
containing low protein concentrations.
 Aqueous humor is formed by the ciliary processes, each of
which is composed of a double layer of epithelium over a
core of stroma and a rich supply of fenestrated
capillaries.
 Each of the 80 or so processes contains a large number of
capillaries, which are supplied mainly by branches of the
major arterial circle of the iris.
 The apical surfaces of both the outer pigmented and the
inner nonpigmented layers of epithelium face each other
and are joined by tight junctions, which are an important
component of the blood–aqueous barrier.
 The inner nonpigmented epithelial cells, which protrude
into the posterior chamber, contain numerous
mitochondria and microvilli; these cells are thought to be
the actual site of aqueous production.

3. The ciliary processes provide a large surface area for
secretion.
Aqueous humor formation and secretion into the
posterior chamber result from active secretion, which
takes place in the double-layered ciliary epithelium
It fills both the anterior and the posterior chambers of
the eye.
Composition:

4. Schematic diagram illustrating the uveoscleral outflow
pathway. Aqueous humor is produced by the ciliary body, in
uveoscleral route, it flows from the posterior chamber through
the pupil into the anterior chamber and then (shown by
dashed lines and arrowheads) through the face of the ciliary
body and iris root to the ciliary muscle and suprachoroidal
space to either veins in the choroid and sclera or through
scleral pores to episcleral tissue.

5.  Aqueous humor is essentially protein free (1/200–1/500 of
the protein found in plasma), which allows for optical
clarity and reflects the integrity of the blood–aqueous
barrier of the normal eye.
 Aqueous humor is produced at an average rate of 2.0–2.5
µL/min, and its composition is altered as it flows from the
posterior chamber, through the pupil, and into the
anterior chamber. This alteration occurs across the
hyaloid face of the vitreous, the surface of the lens, the
blood vessels of the iris, and the corneal endothelium and
is secondary to other dilutional exchanges and active
processes.

6. Functions
 Maintains the intraocular pressure and inflates the globe
of the eye. It is this hydrostatic pressure which keeps the
eyeball in a roughly spherical shape and keeps the walls
of the eyeball taut.
 Provides nutrition (e.G. Amino acids and glucose) for the
avascular ocular tissues; posterior cornea, trabecular
meshwork, lens, and anterior vitreous.
 May serve to transport ascorbate in the anterior segment
to act as an antioxidant agent.
 Presence of immunoglobulins indicate a role in immune
response to defend against pathogens.
 Provides inflation for expansion of the cornea and thus
increased protection against dust, wind, pollen grains and
some pathogens.
 For refractive index.
 Imbalances in the creation and drainage of aqueous humor
can lead to high intraocular pressure (eye pressure or
iop). High intraocular pressure is a major part
of glaucoma and can damage vision.

7. Aqueous Humor Dynamics

8. Introduction
• The main ocular structures related to aqueous
humor dynamics are the ciliary body (the site of
aqueous humor production), and the trabecular
meshwork and the uveoscleral pathway (the
principal locations of aqueous humor outflow).
• IOP is determined by contributions from
• aqueous humor production (aqueous flow)
• trabecular outflow
• uveoscleral outflow
• episcleral venous pressure.
• Aqueous flow has
• a distinctive circadian rhythm
• being lower at night than during the day.
• Aqueous flow is reduced by diabetes mellitus and
myotonic dystrophy.

9. Aqueous flow
 Fluorophotometry
• The best technique to measure aqueous flow in
humans.
• Passage of fluorescein dye in anterior segment
evluated
 Limitations and assumptions:
• a rate of diffusion of fluorescein into the iris,
limbal vessels and tear film is assumed
• fluorescein is distributed uniformly throughout the
anterior chamber and cornea
• a lens-iris barrier is present to block the passage
of the tracer into the posterior chamber
• Short-term fluctuations in aqueous flow not
detectable

10. Trabecular outflow
• The trabecular outflow pathway is comprised of
• the trabecular meshwork
• the juxtacanalicular tissue (JCT)
• the endothelial lining of Schlemm’s canal
• the collecting channels and aqueous veins
• Normal outflow resistance resides in
• the inner wall of Schlemm’s canal (SC) including
the juxtacanalicular tissue (JCT)
• the endothelial lining of SC.
• Hydraulic conductivity
• influenced by the cells in trabecular meshwork of
the inner wall region
• by modulating extracellular matrix turnover by
actively changing cell shape.
• Trabecular outflow is under the influence of ciliary
muscle tone.

11. Uveoscleral outflow
• The uveoscleral outflow pathway is comprised of
• the ciliary muscle
• supraciliary space
• suprachoroidal space
• Sclera
• It is 25-57% of total outflow in young healthy
humans
• Uveoscleral outflow decreased in
• Aging.
• Ocular hypertension
• Uveoscleral outflow increased in
• Uveitis
• Unchanged in
• pigment dispersion syndrome

12. Outflow facility
 In healthy human eyes is
• 0.1 to 0.4 µl / min / mmHg
 Outflow facility is reduced in
• Primary open angle glaucoma
• Ocular hypertension
• PXF or PDS associated with ocular HTN.
• In Primary open-angle glaucoma
• there is an increase in extracellular material in the JCT
• decrease in number of pores in Schlemm’s canal
endothelium.
 Outflow facility can be measured
• Tonography
• Fluorophotometry.
 Uveoscleral outflow
• Calculated from the modified Goldmann equation
• Invasive methods
• The tracer collection method;
• The indirect isotope method

13. Aqueous Humor – Outflow
 The physiology of these two routes differs in several
important ways. For example, the outflow through the
unconventional pathway is relatively independent of the
intraocular pressure unlike the conventional pathway ,
their behavior in response to different pharmacological
agents , also rate limiting step in unconventional pathway
is flow through the ciliary muscle and in the conventional
pathway it’s the flow through the inner wall of schlemm’s
canal . Regulation of the extracellular matrix (ECM)
composition appears to influence aqueous humor outflow
resistance in both the pathways .
 Another mechanism reported to influence aqueous humor
outflow involves age-dependent changes. For instance, in
the healthy aging human eye, a reduction in the
production of aqueous humor is balanced by a reduction
in its drainage through the uveoscleral outflow pathway,
thereby leaving intraocular pressure relatively unchanged.

14. Episcleral venous pressure
 Episcleral venous pressure
• in healthy humans is 8 to 10 mmHg.
• It is affected by
• body position
• inhalation of O2
• application of cold temperature
• treatment with vasoactive drugs
 Episcleral venomanometry
• is used in clinical studies.
• measurement is difficult to make and highly
variable
 Direct cannulation
• is used in animal studies.
• is an accurate but invasive method.

15. Anterior Chamber Examination
 Anterior Chamber Depth:
• Pentorch
• Slit-Lamp
 Anterior Chamber Angle:
• Slit-Lamp (von Herrick)
• Direct Gonioscopy
• Indirect Gonioscopy
• Indentation Gonioscopy

16. Pentorch
• Light shone from temporal side
• Shadow in shallow AC

17. Gonioscopy
 Angle Width:
• O - Contact
• I - Closed
• II - Narrow
• III - Open
• IV - Wide Open
modified Shaffer:
– no structure visible
– schwalbe’s line visible
– trabecular meshwork visible
– scleral spur visible
– ciliary body visible
von Herick:
– PCD < ¼ of corneal thickness
 Iris Insertion:
• Anterior to schwalbe’s line
• Behind trabecular meshwork
• Centered on scleral spur
• Deep on scleral spur
• Extremely deep on ciliary body
 Iris Configuration:
• queer
• regular
• steep
 Trabecular Pigmentation:

18. View of the Angle

19. Slit-lamp Parameters
• Short Slit
• Low Light
• Maximum Magnification
Illumination Arm
- 45° - nasally

20. Direct Gonioscopes
• Koeppe
• Swan-Jacob
• Layden
(infants)
• Worst
• Thorpe
• Medical
workshop
prismatic

21. Indirect Gonioscopes
 Goldmann
 CGA 1.4 Lasag

22. Indendation Gonioscopes
 Zeiss
 Posner
 Sussman

23. UBM

24. Thank You