Gonioscopy

1. GONIOSCOPY MADE BY : SWATI PANARA FROM : BHARTIMAIYA COLLEGE OF OPTOMETRY 2 nd YEAR 4 th SEMESTER

2. INTROUCTION THE TERM GONIOSCOPY WAS COINED BY TRANTAS IN 1907. IT IS A CLINICAL TECHNIQUE THAT IS USED TO EXAMINE STRUCTURE IN THE ANTERIOR CHAMBER ANGLE.

3. PURPOSE OF GONIOSCOPY WHY DO I NEED PERFORM GONIOSCOPY ?? - fundamental part of comprehensive exam. - done initially for all glaucoma patient and suspects. - repeated periodically for patients with angle closure glaucoma.

4. WHAT CAN I ACHIEVE WITH GONIOSCOPY ?? - Visualization of anterior chamber angle - view of the peripheral iris - differentiation between angle closure , occludable and secondary glaucoma.

5. WHAT SHOULD I LOOK FOR IN GONIOSCOPY ? - level of iris insertion - shape and profile of peripheral iris - estimated width of the angle approach - degree of trabecular pigmentation - areas of iridotrabecular apposition

6. PRINCIPLE The total internal reflection at the cornea occurs because the angle of incidence of the rays from the anterior chamber angle structure is greater than the critical angle of the cornea – air interface , which is approximately 46°

7. TYPES

8. DIRECT GONIOSCOPY It is performed with a steep convex lens which permits light from the angle to exit the eye closer to the perpendicular at the lens – air interface. These lenses are used with a operating microscope. Direct gonioscopy is useful but fairly impractical for routine use.

9. TYPES

10. KOEEPE LENS It is the most commonly used for diagnostic direct gonioscopy.

11. HUSKINS BARKAN’S LENS It is a prototype surgical goniolens used for goniotomy. SWAN JACOB’S LENS It is also used for surgical purpose. . SIEBACK GONIOLENS It is a tiny goniolens which floats on the cornea.

12. RICHARDSON – SHAFFER’S LENS It is basically a small Koeppe lens used for infants. WORTH GONIOLENS It anchors to cornea by partial vacuum .

13. TECHNIQUE Cornea is first anaesthetized with 4% xylocaine instilled topically. Ideal position – patient lying supine with the examiner sitting on the side of the eye. Patient looking up , lower lip of the goniolens is inserted below the lower lid. Patient is asked to look down and upper lip is placed beneath upper lid.

14. Now the patient’s head turned towards the examiner , the nasal lip of goniolens is slightly raised and normal saline drops are used for irrigation Now gonioscopy is performed with the patient looking to the ceiling.

15. ADVANTAGE Greater flexibility Used in goniotomy surgery Used in anaesthetized patients as in infants Causes lesser distortion of anterior chamber angle becomes deep in supine position so it is easy to see the angle. Panoramic view is obtained so one part of angle could be compared with the other.

16. Using two lenses , both eyes can be examined simultaneously. Provide a straight view rather than inverted view. Detailed examination of minor structure is possible.

17. DISADVANTAGE Inconvenient Annoying light reflex from cornea Time – consuming Benefits of slit lamp are not available

18. INDIRECT GONIOSCOPY Indirect gonioscopy uses mirrors or prism to over come the problem of total internal reflection. Moreover , it uses the slit lamp’s illumination and magnification system to its advantage.

19. TYPES

20. GONIOPRISM REQUIRING COUPLING AGENT

21. GOLDMANN THREE MIRROR GONIOPRISM The mirror having inclination of 59° and domed upper border is used for gonioscopy. (1) the mirror inclined at 67° is used to examine pars plana area of ciliary body. (2) the mirror having inclination of 73° is used to examine ora serrata area of peripheral fundus.

22. GOLDMANN TWO MIRROR GONIOPRISM Both the mirrors are inclined at 62° It need to be rotated once to examine the whole angle. Laser trabeculoplasty

23. GOLDMANN SINGLE MIRROR GONIOPRISM The mirror is inclined at 62° It is prototype diagnostic gonioprism. It is to be rotated three times to examine the whole angle.

24. ADVANTAGE OF GOLDMANN GONIOPRISM Easy to use Excellent view Stabilizes the globe and there for can be used in argon laser trabeculoplasty. Peripheral retina can be seen Goldman two mirror gives best In – situ view of the angle.

25. DISADVANTAGE OF GOLDMANN GONIOPRISM Curvature of lens is more than that of cornea so a coupling material is required. it blurs vision and fundus therefore field charting , direct and indirect ophthalmoscopy cannot be done immediately after its use. It cannot be used for indentation gonioscopy. Only one mirror is there for gonioscopy so it needs to rotated by 360°

26. ALLEN – THROPE GONIOPRISM It has got four prisms instead of mirror and allows examination of the whole angle without rotating the prisms.

27. GONIOPRISM NOT REQUIRING COUPLING AGENT

28. ZEISS FOUR MIRROR GONIOPRISM Four identical mirrors angled at 64° which allow examination without rotation of the lens. ADVANTAGE : coupling material not required Easy to perform when mastered Indentation gonioscopy can be performed DISADVANTAGE : difficult to master Does not stabilize the globe

29. POSNER LENS It is similar to zeiss gonioprism but is made of plastic instead of glass and also has fixed rather than detachable handle.

30. TOKEL GONIOPRISM It is a single mirror gonioprism and has got a wider field of view. SUSSMAN LENS It is also similar to zeiss lens except that it has no handle.

31. TECHNIQUE Eye is anaesthetized with the topical anaesthetic anent Patient who is sitting on the slit lamp is asked to look down The thumb of one hand is used to retract the upper lid. The lower edge of the gonioscope is placed on the lower lid. Slit lamp beam is focused on the mirror that shows the angle diametrically opposite to it.

32. ADVANTAGE Easier to learn. Faster to perform. Requires less instrumentation and space. Slit lamp provides better optics and lighting. Indentation gonioscopy can also be done. Magnified stereoscopic view of optic disc can also be obtained.

33. DISADVANTAGE Comparison is not possible. Limited positioning of light rays. Difficult to perform in horizontal meridian. Mirror image seen , so confusing. Excessive pressure may open or close the angle artefactually.

34. RECORDING Most posterior angle structure observed. Angular approach at the recess. Iris contour Amount of pigment to what degree the angle opens with indentation Surgical alteration such as sclerectomy and peripheral iridotomy.

35. GRADING SYSTEM FOR THE ANGLE OF ANTERIOR CHAMBER

36. SCHEIE’S GRADING Grade 1 narrow = hard to see over iris root into recess Grade 2 narrow = ciliary body band obscured Grade 3 narrow = posterior trabeculum obscured Grade 4 narrow = only schwalbe’s line visible.

37. SHAFFER’S GRADING SYSTEM Grade 0 —PARTIAL OR COMPLETE CLOSURE Grade I </= 10° angle of approach Grade II -20° angle of approach Grade III 20°–35° angle of approach Grade IV 35°–45° angle of approach

38. RP CENTRE GONIOSCOPIC GRADING Grade 0 = no dipping of the beam Grade 1 = dipping of the beam Grade 2 = schwalbe’s line and anterior one – third of the trabecular meshwork visualized. Grade 3 = middle one – third of trabecular meshwork visualized. Grade 4 = posterior one – third of trabecular meshwork Grade 5 = scleral spur visualized Grade 6 = ciliary body band visualized

39. SPEATH CLASSIFICATION

40. GONIOSCOPIC VIEW OF ANGLE STRUCTURE

41. SCHWALBE’S LINE Termination of descement’s membrane It is marked only by a slight change in colour from trabecular meshwork or by a faint white line. Important landmark in identifying the gonioscopic anatomy in confusing angle.

42. TRABECULAR MESHWORK It has an anterior non pigmented trabecular meshwork and posterior pigmented trabecular meshwork.

43. CILIARY BODY BAND It is light grey or dark brown just posterior to the scleral spur.

44. ROOT OF IRIS Iris contour is slightly convex or flat. Colour varies in different individuals.

45. GONIOSCOPIC TECHNIQUE

46. CLINICAL USE OF GONIOSCOPY Differentiation between primary open angle glaucoma and primary closure angle glaucoma To diagnose and provide a prognosis for the congenital glaucoma. To diagnose secondary glaucoma and unusual causes of glaucoma. For treatment To diagnose condition like tumours of anterior segment , intraocular foreign body.

47. LIMITATION Cannot be performed in painful inflamed eyes. Difficult to perform in case of acute glaucoma where eyes are painful.

48. REFERENCE CLINICAL PROCEDURE IN PRIMARY EYE CARE – DAVID B. ELLIOTT OPTIC AND REFRACTION – A K KHURANA NET PURAB SIR’S NOTES COMPREHENSIVE OPHTHALMOLOGY – A K KHURANA KANSKI

49. Thank you