Gonioscopy

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 Secondary to appositional angle closure, creeping angle closure, inflammation, neovascular membranes, ICE syndrome and trauma. 


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

19. TYPES OF LENS

20. 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.

21. 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.

22. Gonio Two mirror. Gonio Three mirror.

23. 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.

24. Techniques of gonioscopy

25. SEAGIG Guidelines

26. 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

27. 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.

28. 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.

29. 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.

30. 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.

31. 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.

32. 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.

33. 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.

34. 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.

35. 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.

36. 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

37. Torch Light Examination Prior to Gonioscopy Eclipse Sign. Screening Purpose.

38. 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

39. 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.

40. 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

41. 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.

42. 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.

43. 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.

44. 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.

45. 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.

46. 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.

47. 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.

48. Thank you!