Detailed PPT on Gonioscopy, Types, Methods and Representation

1. Dr Rishika Lakshminarayana
GONIOSCOPY

2. Alexios Trantas,
1907
Maximilian Salzmann, 1915

3. Otto Barkan, 1937 Hans Goldmann, 1938

4. What is
Gonioscopy?
• Coined by Alexios Trantas, 1975.
• Greek - “Gonia” and “skopein”.
• Gonioscopy is the clinical technique
which allows the structures of the
anterior chamber angle to be visualised.

5. Normal Anatomy of
the Angle
• Schwalbe’s line
• Trabecular Meshwork
• Scleral Spur
• Ciliary Body

6. Schwalbe’s line
• Termination of the Descemet’s
membrane.
• Fine ridge anterior to trabecular
meshwork - pigment.

7. Trabecular
Meshwork
• Pigmented band anterior to scleral spur.
• Anterior - Schwalbe’s line and anterior
edge of Schlemm’s canal.
• Posterior – Functional part - Primary site
of aqueous out flow.

8. Scleral Spur
• Posterior lip of scleral sulcus - attached
to the ciliary body and corneo-scleral
meshwork.
• White line.

9. Ciliary Body
• Visible part of Ciliary body in A.C - Iris
insertion into ciliary body.
• Width depends on level of iris insertion.
• Grey to dark brown

10. Important gonioscopic
Landmarks

11. Corneal Wedge
• Most important step in gonioscopy to identify is the
corneal wedge - Why?
• Thin slit of light at the Irido-corneal angle - two light
reflections - external and internal corneal surfaces -
sclero-corneal junction (Schwalbe’s line) marking
the anterior border of trabecular meshwork.

12. • Corneal wedge is not visible? Iris is
obscuring the trabecular meshwork.
• The next step is to identify whether
there is irido-trabecular contact and
assess the angular width between
the peripheral iris and the trabecular
meshwork.
• If neither epithelial nor endothelial
line is visible then there may be
obscuring corneal pannus or
scarring.
• Superior and inferior angles - the
beam vertical.
• Nasal and temporal angles - the
beam should be horizontal.

13. Schlemm’s canal
• Non-pigmented angle, deep to the posterior
trabecular meshwork.
• Blood can sometimes be seen in this canal if
the goniolens compresses the episcleral
veins such that the episcleral venous
pressure exceeds the IOP.

14. Blood vessels
• Radial pattern at the base of the angle
recess.
• Approximately two-thirds of individuals
with blue eyes and in 10% with brown
eyes.
• Any blood vessel that crosses the scleral
spur onto the trabecular meshwork is
abnormal.

15. Normal Blood Vessels Neovascularisation
Radial Orientation, thick Fine
Non branching Arborising
Does not cross scleral spur Crosses scleral spur

16. Iris processes
• Normal variation.
• These are small extensions of the anterior
surface of the iris which insert at the level of the
scleral spur and cover the ciliary body to a
varying extent.
• Iris processes should not be confused with
peripheral anterior synechiae.

17. Iris Processes
Peripheral Anterior
Synechiae
Fine Broad
Extend into scleral spur Extend beyond scleral spur
Follow concavity of recess Bridge the concavity
Underlying structures are
seen
Structures are not seen
Moves with indentation Stationary - resists movement
Normal variation

18. Principles of Gonioscopy
Critical angle ~ 46deg
Koeppe Lens Goldmann Lens

19. TYPES OF LENS

21. Direct Goniolens
Koeppe
• Dome-shaped direct goniolens.
• It is easy to use and provides a panoramic view of the
angle.
• Simultaneous comparison of one portion of the angle with
another.
• Offers greater flexibility.
• It cannot be used in conjunction with a slit-lamp and
therefore does not provide the same clarity and
illumination.

22. Indirect
Goldmann Single Mirror
• Contact surface diameter- 12 mm.
• Mirror inclined at 62°.
• Relatively easy to master, it affords an excellent
view of the angle.
• It also stabilizes the globe and is therefore suitable
for argon laser trabeculoplasty.
• Requiring viscous coupling substance - Perimetry,
ophthalmoscopy, or photography of the discs
should performed before gonioscopy.

23. • Gonio Two mirror.
• Gonio Three mirror.

24. Zeiss
• Indirect four-mirror goniolenses mounted on a
handle.
• Diameter of 9 mm.
• Curvature flatter than that of the cornea - no
coupling substance.
• All four mirrors are inclined at 64°.
• Quick and comfortable examination of the angle
and does not interfere with the subsequent
examination of the fundus.
• The four mirrors enable the entire circumference
of the angle to be visualized with minimal rotation.
• The lens is useful for indentation gonioscopy.

25. Techniques of
gonioscopy

26. SEAGIG Guidelines

27. • Direct gonioscopy is performed with the patient in a supine position under topical anaesthsia.
• The goniolens is positioned on the cornea using a coupling agent.
• Gonioscope in one hand and a light source(Barkan illuminator) in the other.
• Gonioscope with mounted light source may be used, which allows the examiner to control the
goniolens with the other hand.
Direct Gonioscopy

28. • The examiner scans by shifting his or her position until all 360deg are covered.
• The patient lies in a supine position with the head turned towards the examiner and
eyes looking at the examiner’s nose.

29. Goldmann
• Counselling the patient.
• Topical anesthetic.
• A coupling fluid is inserted into the cup of the lens.
• The patient is instructed to look up and the inferior rim
of the lens is inserted into the lower fornix and then
pressed quickly against the cornea so that the coupling
substance does not escape.
• The patient is then asked to gaze ahead with the other
eye.

30. • The angle is visualized with a gonioscopic mirror.
• Initially the mirror is placed at the 12 o’clock position to visualize the inferior angle and
then rotated clockwise.
• Slit beam - 2 mm wide and at right angles to the mirror.

31. Iris insertion - Looking “Over the Hill”
• In primary position - Convex iris profile can obscure a narrow gap between iris and trabecular
meshwork.
• Oppositional.
• When the view of the angle is obscured by a convex iris - “over the hill”
• A very gentle rotation of the lens may be all that is needed to ‘look over the hill’ and confirm that
there is no iridotrabecular contact.
• Accidental indentation - wider angle.
• Movement of the lens is the best approach.

32. • By asking the patient to look in the direction of the mirror.
• When the plane of the iris is flat, the patient should be asked to look away from the mirror
in order to obtain a view parallel to the iris with optimal image quality.
• This is particularly important when performing laser trabeculoplasty.

33. Zeiss
• A coupling fluid is not required.
• The lens is placed directly on the center of the cornea.
• Only gentle contact with the cornea is needed because excessive pressure
will inadvertently distort angle structures.
• Each quadrant of the angle is visualized with the opposite mirror.
• The central fundus can be viewed through the center of the lens.

34. Indentation
• In the primary position - the level of iris
contact with the eye-wall and the angular
width of the anterior chamber angle.
• Indentation/Manipulative/Dynamic
gonioscopy - applying pressure to the central
cornea and so increasing the anterior
chamber pressure and forcing aqueous fluid
into the angle.

35. • In the absence of iridotrabecular contact, the
level of iris insertion is determined.
• If iridotrabecular contact is present -
“appositional” or “synechial”.
• Indentation is best performed with 4-mirror
lenses which have a smaller contact area.

36. DIRECT GONIOSCOPY
• Panoramic view of iridocorneal angle with ability to adjust view by examiner.
• Both eyes can be examined simultaneously.
• No viscous [ coupling ] material required.
• Direct view for surgery e.g. Goniotomy
• DISADV: Inability to perform indentation, low magnification, assistance.

37. INDIRECT GONIOSCOPY
• Indirect - Segmental View
• One Eye at a time
• Coupling agent is required
• Mirror Image seen
• Excellent optics with Slit Lamp
• Indentation Can be Done

38. Torch Light Examination
Prior to Gonioscopy
• Eclipse Sign.
• Screening Purpose.

39. • VH (Van Herick Grading) - The limbal chamber depth (LCD)
Assessed at a slit-lamp with the illumination column at 60
degrees.
• The brightest, narrowest possible vertical beam of light is
directed at the temporal limbus with the beam of light
perpendicular to the ocular surface and viewed from the
nasal aspect.
• The beam is positioned at the most peripheral point that
gives a clear view of both anterior chamber and peripheral
iris and then viewed at maximum magnification.
• The limbal chamber depth may be graded according to
classic grading schemes, e.g. 1 to 4

40. GRADING
• Main aims are to evaluate the functional status of the angle, the degree of closure and the
risk of further closure.
• It is important to determine:
• The geometrical angle width in degrees
• The shape and contour of the peripheral iris
• The most posterior structure seen
• The presence of peripheral anterior synechiae
• The amount of trabecular pigmentation.

41. • The Scheie grading system is based on the extent of visible angle structures.
• Obselete.
• The scale of I–IV is the reverse of the Shaffer grading system.11
Scheie

42. Shaffers
• The Shaffer system records the angle in degrees of arc subtended by two imaginary
tangential lines drawn to the inner surface of the trabeculum and the anterior surface of the
iris about one third of the distance from its periphery.
• Estimates geometric angle between iris and cornea.

43. Spaeth -
• Describes features identified by Scheie and Shaffer schemes as well as the iris profile and level of
true and apparent iris insertion.
• It was designed for indirect goniolenses (e.g., Zeiss four mirror) that allow for indentation
gonioscopy.
• Interobserver variability has been found to be minimal.
• The Spaeth grading system uses an intricate alphanumeric scale, attempting to provide three-
dimensional specificity to gonioscopic description.

45. Schematic Representation
• Goniogram - easy pictorial representation of
gonioscopy findings.
• Things to be recorded -
• Posterior most structure seen.
• Effect of manipulation or indentation.
• Mention iris configuration , recess and indentation.

47. Sterilization of gonio
lens
• Any instrument that contacts the eye creates the potential
hazard of trans- mitting bacterial and viral infection.
• Common disinfectants are - alcohol, glutaraldehyde,
sodium hypochlo- rite, (household bleach), formalin and
phenol.
• In 1988 the American Academy of Ophthalmology, the
National Society to Prevent Blindness, and the Contact
Lens Association of Ophthalmologists jointly issued
guidelines for disinfection.

48. Uses of Gonioscopy
Diagnostic and Therapeutic
• Diagnostic -
• Classification : Open or Closed angle
glaucoma.
• To assess AC angle recess & risk of angle
closure.
• To identify plateau iris.
• To look for Abnormal angle pigmenatation.
• PEX
• Angle recession
• Cyclodialysis
• Foreign body
• Neoplasm
• Blood in Schlemm’s canal.
• Evaluation of trabeculectomy fistula ,
glaucoma drainage devices.
• Congenital anomalies- aniridia, iris
processes.

49. • Therapeutic -
• Laser trabeculosplasty.
• Goniophtocoagulation
• Goniotomy
• Gonioplasty
• Trabectome surgery
• Reopening of blocked trabeculectomy opening.
• Laser of suture around tube of G.D.D.
• Indentation Gonioscopy to break an attack of Acute ACG.

53. RetCam Gonioscopy Technique
• Can be used to view the angle structures with
anterior focus of the lens.
• Provides a non-distorted view using optical
fibre connected to light emitting control unit
and a video camera.
• Advantage of clearer image at higher
magnification.

54. Thank you!