Gonioscopy

1. What is Gonioscopy Gonioscopy is an examination of the eye to look at the anterior chamber from the ant. part of iris to the post. part of cornea using the help of gonio - lens and slit lamp.

2. The Who of Gonioscopy

3. P ioneer Alexios Trantas : The first person to examine angle in the Anterior chamber in a living eye. In 1900 with the aid of direct ophthalmoscopy and stimulating digital pressure on corneo -scleral capsule he examined – ciliary body, ora serrata and , the anterior chamber . 1901 – Gazette Medicale d’Orient .

4. Maximilian Salzmann : He reported that light that emanates from the angle undergoes ‘total internal reflection’ and thus, cannot be intercepted by ophthalmoscope due to change in medium He indicated that indirect ophthalmoscopy give’s a better view of angle than that of direct ophthalmoscopy. He later calculated that the lens with smaller radius of that of cornea would facilitate Gonioscopy (Zeiss scleral contact lens 7mm).

5. Impact Of Slitlamp Biomicroscopy 1920- Zeiss perfected the first slitlamp basing on principle of Noble laureate Allvar Gullstrand (Sweden) and Czapski’s corneal microscope. Koeppe (Germany) : Mathematically calculated the most adv. Contact lens and gave the method biomicroscopy of angle of ant. Chamber with slit lamp ( magni . – 40 dia )

6. He could see the nasal and temporal aspects of angle in sitting position of patient with the help of new more convex and thicker lens. Koeppe’s method improvised by Ascher and used on recumbent patients made it possible to visualizing inferior and superior angles Koeppe’s method is still been used for direct gonioscopy without reflecting surface

7. The American Pioneer Manuel Uribe Troncoso : Involved in Gonioscopy due to interest in glaucoma 1925-Discribed self illuminating mono-ocular G onioscopy with its complex arrangment of reflecting prisms ( mag: 30 dia ) 1941- Discribed chamber angles in various glaucoma’s 1947 – Wrote first comprehensive book on Gonioscopy Clarified the anatomical terminology of structures of angle seen in Gonioscopy .

8. Otto Barkan He combined Koeppe’s contact lens, the light powerful Vogt carbon-arc slit lamp and Zeiss binocular microscope which gave 40x mag. He coined the term ‘open angle glaucoma’ and suggested that, sclerosis of trabecular meshwork was the cause for raise in IOP He devised internal trebeculectomy under microscopy which spurned to todays external trebeculectomy and trebeculectomy

9. Contd … He was able to correlate the raise of IOP in eyes with narrow angle glaucoma with closure of angle by root of iris naming ‘narrow angle glaucoma’ and advocated peripheral iridectomy as a cure. Barkan and Maisler studied the exact topography of angle structures .

10. Goldmann’s Gonioscopy It was Goldmann a Swizz Ophthalmologist in Prague who popularised gonioscopy in Europe, not only by introducing a simple and superior method of examination but, also through his papers which confirmed Barkan’s observations. Allen, Braley and Thorpe (1945) with four reflecting surfaces gave a miter shaped gonioscope where external curvature of koeppe lens was replaced by a prism which stayed on the cornea by capillary attraction.

11. Why do we need Gonioscopy As the recesses of the angle of anterior chamber are difficult to visualize since this region is covered by projecting shelf of sclera at the limbus and all the emergent light is subjected to total internal reflection.

12. Why do we need Gonioscopy Fundamental part of comprehensive exam Most important factor in correct diagnosis Done initially for all glaucoma patients and suspects Repeated periodically for all angle – closure glaucoma patients

13. Purpose of Gonioscopy Visualization of anterior chamber angle View of peripheral iris Difference between angle – closure, occludable , and secondary glaucomas

14. Other ways to evaluate the angle Scheimpflup photography Ultrasound biomicroscopy

15. Anterior Segment optical coherence tomography

16. Principle of Gonioscopy

17. Criticle angle When light is passing from a medium with greater refractive index to one with lesser refractive index angle of refraction ( r) will be larger than angle of incidence( i ) Critical angle is where ‘r’ = 90⁰ When ‘I’ exceeds critical angle the light is reflected back into the medium Critical angle for corneal-air interface = 46⁰ Light from A.C. angle as exceeds the critical angle is reflected back into the anterior chamber leading to ‘ Total internal reflection’

18. Critical angle, cornel and goniolens

19. Principle of Gonioscopy

20. Method of Gonioscopy

21. Common Goniolens and Types lens description Indirect goniolens goldmann single mirror Mirror inclined at 62⁰ Zeiss four mirror All mirrors at 64⁰ , no fluid bridge requried Posner four mirror Modified Zeiss with handel Sussman four mirror Hand held Zeiss model Ritch Trabeculoplasty lens Four mirror’s : 2 at 59⁰ and 2 at 62⁰ , with a convex lens over two of the mirror’s Direct goniolens Koeppe Dome shaped lens Barkan Quarter sphere, surgical and diagnostic lens Swan -Jacob Surgical goniolens for children

22. Direct Gonioscopy Instruments : goniolens , gonioscope or hand bio-microscope (15-20x) and a light source

23. Direct Gonioscopy Advantages Observer’s height can be changed to look deep or get a better look at the angle structre’s As done in supine position it can be used for sedated, comatosed , or in children Useful in examining the fundus with small pupil with D.O Straight on the view Panoramic view of the angle structure’s Comparison of angle recession Causes less distortion of A.C.

24. Direct Gonioscopy Disadvantages Inconvenient Special equipment needed

25. Indirect G onioscopy Instrument's used : gonioprism and a slitlamp Most widely used gonioprisum : Goldmann G oldman single mirror Height of the mirror : 12 mm Angle of the mirror : 62 ⁰ Central well diameter : 12mm Posterior radius of curvature : 7.38 mm Goldmann three mirror One mirror for examination of anterior chamber : 59⁰ Two mirror’s for examination of fundus. The posterior radius of curvature is such that both the lens need viscous material to fill the space

26. Contd … Modified Goldmann lens have been developed One with a posterior curvature of 8.4 mm eliminating the need of a viscous material Another with a anti-reflecting coat used in laser trabeculoplasty

27. Indirect G onioscopy

28. Indirect Gonioscopy

29. Indirect Gonioscopy

30. Four mirror lens Zeiss four mirror lens, all at an angle of 64⁰ eliminating the need for rotating Original four mirror is on a Unger Holder Posner has a fixed holder Sussman is held directly Posterior curvature of all these lens is equal to that of cornea which allows the patien’s own tears to form the fluid bridge

31. Indirect Gonioscopy

32. Indirect Gonioscopy

33. Indirect Gonioscopy

34. Indirect Gonioscopy

35. Slit lamp technique

36. Slit lamp technique

37. Indirect Gonioscopy

38. Indirect Gonioscopy

39. What to see While performing a direct or an indirect Gonioscopy and starting from the root of the iris and moving anteriorly to cornea the structure’s to be identified and examined are Ciliary body band Scleral spur Functional trabecular meshwork Schwalbe’s line Normal blood vessels

40. Normal Angle Structures

41. Pupil It is best to start at the pupil for rapid orientation Anterior lens surface is observed for focal opacification and posterior synechiae This position is also good for examining dandruff flake's like exfoliations on the pigment at the posterior edge of pupil – Exfoliation syndrome Iridodonesis – to a small extent seen in normal eye and easily observed in pathognomic one

42. Angle Structures : Iris Contour flat – deep A.C Convex – shallow A.C. , hyperopia Concave – high myopia, pigment dispersion synd. Abnormal last rolling – plateau iris

43. Angle Structures : Iris Site of insertion : while examining the iris care should be taken in distinguishing the apparent and actual juncture This is established by the use of indentation Gonioscopy Angulation : It is the angle between iris insertion and slope of the inner cornea in the A.C .( 10⁰) Abnormalities : neovascularization, hypoplasia, atrophy

44. Angle Recess Is seen beyond the final roll of iris At birth – incomplete 1sr yr of life it firms a concavity into the anterior surface of the ciliary body

45. Angle Structures : Ciliary Body band This structural portion of ciliary body is visible in the A.C. as a result of iris insertion Width depends on level of iris insertion Wider in myopes and narrow in hyperopia Color: grey to dark brown

46. Angle Structures : Scleral Spur This is the post. Lip of scleral sulcus which is attached to the ciliary body posteriorly and corneo -scleral meshwork anteriorly Color : prominent white line

47. Angle Structures : Scleral Spur May be obscured by Iris process iris bombe Peripheral anterior synechiae pigments

48. Angle Structures : Trabecular Meshwork Pigmented band anterior to scleral spur Although extent of TMW is from root of iris to schwalbe’s line it is considered as 2 portions Anterior - between schwalbe’s line and ant. Edge of schlemm’s cannal Involved in lesser degree of aqueous out flow Posterior – Functional part , primary site of aqueous out flow Appearance of funtional TMW depends on amount of pigmant deposition

49. Angle Structures : Trabecular Meshwork At birth no pigment and with age from faint to dark brown Pigment deposition may be homogeneous or irregular When lightly pigmented blood reflex in schlemm’s cannal may be seen as a red band

50. Angle Structures : Schwalbe’s line Junction between anterior chamber angle structures and cornea where the descement’s membrane terminates Fine ridge ant. to TMW identified by a small built up of pigment Landmark for TMW in narrow angle

51. Angle Structures : Schwalbe’s line

52. Angle Blood vessels

53. Differentiating between iris processes and synechiae

54. Manipulation's Sometimes the iridocorneal angle is quite confusing  Often the angle is difficult to interpret because there is too much or too little angle pigmentation In such cases manipulation’s are used for better viewing and diagnosis

55. Technique for examining difficult angle’s Looking over the hill Corneal wedging Indentation Van- Hericks test

56. Look over the hill WHAT ? Sometimes the iris is bowed forward making visualization of the iridocorneal angle quite challenging WHERE ? Open angle with iris bowing , cholinergic agents such as pilocarpine WHY ? To know weather the angle is occluded or not

57. Over the Hill Gonioscopy

58. Corneal Wedge WHAT ? When a thin slit of light hits the irido -corneal angle at an angle of 10⁰-15⁰, two light reflections are seen from the external and internal corneal surfaces which pipe down at the sclero -corneal junction ( Schwalbe’s line) marking the anterior border of trabecular meshwork

59. WHY ? corneal wedge is a useful technique to identify the trabecular meshwork in eyes that are either nonpigmented or excessively pigmented its diff. to mark trabecular meshwork begins WHERE ? Y oung patients where the trabecular meshwork has not yet developed any pigmentation WHY ? To diff. wide-open and nonpigmented angle or a totally closed angle where one is looking at the internal cornea.

60. The Corneal Wedge

61. The Corneal Wedge

62. Indentation Gonioscopy When iris covers the trabecular meshwork (TM) its easy to mistake: The non-pigmented TM for scleral spur Pigmented Schwalbe’s line for TM Apposition from synechiae Indentation Gonioscopy is particularly useful in these cases

63. Indentation Gonioscopy Useful when iris surface is convex Done when recognition of angle structures is difficult Performed in all glaucoma cases Differentiates appositional vs synechial closure in pupillary block Measures extent of angle closure Identifies plateau iris config . Identifies lens induced angle closure

64. Recognition of sites of blockage in angle closure Pupil block Plateau iris

65. Indentation Gonioscopy

66. Indentation Gonioscopy : Synechial closure

67. Plateau iris configuration large or anteriorly positioned ciliary processes that push the peripheral iris forward

68. Indentation : plateau iris

69. Indentation : cilicary body pseudo-plateau iris

70. VAN HERICK’S method of cornael thickness as a unit of measure WHAT ? The Van Herick test is a slit lamp estimation of the angle depth WHY ? T o estimate the angle width WHERE ?  In nonpigmented angles it can be difficult to determine whether the angle is open or closed

71. Thin bright slit 60⁰ from temporally is brought into cornea until A.C. is located compared with depth of peripheral A.C. If the depth of the A.C = corneal thickness then it’s a wide open angle

72. The Speath method

73. Grading of Angle Width : Shaffer’s

74. Difficulties in gonioscopy Koeppe’s lens: Scleral lip pressing on outer sclera causing narrowing of angle Zeiss lens: excessive pressure on central cornea causes angle widening and descement’s folds Air or methylcellulose collected on inner surface removed with soap water All lenses cleaned with dil.bleach or hydrogen peroxide after use