Diagnosis and Assessment of anterior chamber of eye.. measurement of anterior chamber angle and anterior chamber depth.

1. -L.Sai Charan
IMSc Optometry and Vision Sciences
School Of Medical Sciences
University of Hyderabad

2. Parts include Anterior chamber
are:- (From posterior to anterior)
 Pupil. Visible with the gonioscope if dilated.
 Iris. Colour varies between individuals.
 Ciliary body. Longditudinal muscle. Colour varies
between individuals - may be pale brown, grey or dark.
 Scleral spur. Protrusion of sclera into anterior
chamber. Attached to ciliary body posteriorly and
trabecular meshwork anteriorly.

3. Parts include Anterior chamber
are:- (From posterior to anterior)
 Trabecular meshwork. Multilayered network of




fenestrated lamellae and endothelial cells draining aqueous
into Canal of Schlemm which may visible when full of
blood (e.g. in hypotony or when excess force applied to
sclera during gonioscopy).
The multi-layers include
1) Anterior Trabecular meshwork
2) Posterior Trabecular meshwork
Most of the drainage occurs via the posterior, more
pigmented, portion of the trabecular meshwork. There are
variations in colour but usually grey with varying degrees of
pigmentation

4. Parts include Anterior chamber
are:- (From posterior to anterior)
 Schwalbe's line. Delineates the anterior edge of the
trabecular zone and represents the termination of
Descemet's membrane. Very fine glossy white line.

5. Reasons for anterior chamber
examination include:
 To rule out anterior segment inflammation (e.g.
anterior uveitis )
 To detect eyes at risk from angle closure
 To differentially diagnose open angle, closed angle,
primary and secondary glaucoma.
 To assess eyes at risk from developing anterior
chamber sequelae to other disease e.g. diabetes
mellitus, CRV occlusion

6. Assessment of anterior chamber
include: Assessment of anterior chamber angle (ACA):-
anatomical angle created by the root of the iris and the
peripheral corneal vault.
 Assessment of anterior chamber depth (ACD):-
Aqueous-containing space of the eyeball between the
cornea and the iris.

7. Methods that can assess the ACA
and ACD in clinical practice are: Pen torch method
 Smith’s method
 Van Herrick’s technique
 Split limbal technique
 Optical coherence tomography
 Gonioscopy

8. Pen Torch method: Shine a pen torch into the pt’s eye from the temporal
canthus such that the pen torch lies in the same plane
of eye.
 In the case of a deep anterior chamber, the iris lies flat
and the whole iris will be illuminated.
 In the case of a very shallow anterior chamber the iris
lies forward, blocking some of the light and very little
of the iris is illuminated.

9.  Based on the amount of eye illuminated the ACD can
be graded.
Figure 1 :Grading of anterior chamber angle/depth using the pen
torch method

10. Smith’s method: Is a quantitative method of measuring the ACD.
 It is carried out using a slit lamp with the observation
system directly in front of the patient’s eye and the
illumination system at an angle of 60° to the temporal
side.
 A beam of approximately 1.5mm thickness, with its
orientation horizontal, is placed across the cornea.
 Strain tear film with the fluroscein (for an easy
assessment)

11.  A second horizontal beam is then seen in the plane of
the crystalline lens.
 The length of the beam is adjusted until the beams on
the cornea and crystalline lens just appear to meet
 The length of the beam is read directly from the slit
lamp and this number is multiplied by 1.34 to
calculate the ACD.

12. Van Herrick’s technique: Common quantitative method of assessing the size of
the ACA using the slitlamp biomicroscope.
 It involves comparing the size of an optic section width
on the cornea to the gap between the section and the
reflection on the iris when a beam is trained just
within the limbus at an angle of 60°.
 It from the limbus the more the angle will be
overestimated. An angle of 60° should be used
consistently to allow for standardisation of
measurements.

13. Van Herrick’s technique: The AC angle width used to be graded on a scale of
grade 0 (closed) to 4 (wide open).

14. Split limbal technique: To estimate the superior and inferior angles the split
limbal technique can be used.
 In this technique the slit lamp is used to provide the
illumination.
 With the illumination in the click position, a vertical
slit should be placed across the superior ACA
at 12 o’clock.
 Observe the arc of light falling on the cornea and iris.

15. Split limbal technique: The angular separation seen at the limbal corneal
junction is an estimation of the anterior chamber
angle depth in degrees.

16. Optical Coherence
Tomography(oct)
 Uses low coherence interferometry to obtain cross-
sectional images of the ocular structures.
 To image the anterior segment, longer wavelength
light (1,310nm) is used.
 Anterior segment OCT can be used to take
measurements of the angle.

17. Gonioscopy: The gold standard for ACA assessment is gonioscopy.
 Use of a slit lamp and gonio-lens.
 Allow direct visualisation into the ACA.
 To carry out gonioscopy, the cornea is anaesthesised
using topical anaesthetic.
 With gonioscopy any abnormalities within the angle
eg, pigment deposition, neovascular growth etc. can be
detected

18. Gonioscopy: The structures visible in a wide angle are (from iris to
cornea)
(a) The ciliary body (CP): this appears slightly darker
than the iris itself,
(b) the scleral spur (SS): a white band just above the
ciliary body,
(c) the trabecular meshwork (TM): this can be a
whitish-grey or pink colour, and
(d) Schwalbe’s line (SL):

19. Structures Visible in Gonioscopy
The visible structures of the anterior chamber angle
during gonioscopy. CP = ciliary body; SS = scleral
spur; TM = trabecular meshwork; SL = Schwalbe’s line

20. Contraindications for gonioscopy:
 Hyphaema
 Compromised cornea (e.g corneal ulcer)
 Lacerated or perforated globe

21. Conclusion
 A full assessment of the ocular health should include
some examination of the ACA and/or ACD.
 The depth of the anterior chamber naturally decreases
with age due to the increase in size of the crystalline
lens and with this decrease comes an increased risk of
narrow and closed angle glaucoma.