Binocular Indirect Ophthalmoscopy

Binocular Indirect Ophthalmoscopy is known to provide a wider view of the inside of the eye. It is one of the most commonly used ophthalmic instrument.

1. Binocular Indirect OPHTHALMOSCOPY Dr.Shah -Noor Hassan FCPS,FRCS Assistant Professor Vitreo -Retina BSMMU

2. History of ophthalmoscope Mery in 1704 made first ophthalmoscopic observation of a normal fundus in a drowning cat Cumming and Brucke in 1846 explained the principles of ophthalmoscopy 2

3. History of ophthalmoscope THREE basic principles described by Hermann von Helmholtz Patient and observer should be made emmetropic Retina of the patient should be sufficiently illuminated Optical alignment of light source and observer’s pupil 3

4. History of indirect ophthalmoscope Ruete in 1852 designed first monocular indirect ophthalmoscope 4

5. History of indirect ophthalmoscope Marc-Antoine Giraud-Teulon of France (1861) Weak source of illumination. 5

6. History of indirect ophthalmoscope 1911-Thorner and Allvor Gullstrand – Reflex free ophthalmoscopy 1946 – Charles Schepens - modern binocular indirect ophthalmoscope 6

7. Gullstrand’s principle The illuminating and viewing beams must be totally separated through the cornea, pupillary aperture, and lens (to avoid reflections) but must coincide on the retina to permit viewing 7

8. Direct vs Indirect Direct Indirect Monocular view Binocular view Limited field of view (10-15 degrees) Wide field of view (35 degrees) Poor view in hazy media Better view in hazy media One has to go very close to the patient Working distance is about 35-40 cms Drawing of retinal lesions is difficult & incomplete Drawing of retinal lesions are easier Difficult to use during surgery Can be used for fundus examination during surgery Illumination: 0.5 – 2 Watts Illumination: 15 – 18 Watts 15 times magnification 2-5 times magnification Virtual and erect image Real and inverted image 8

9. Monocular indirect ophthalmoscope Instrument: Magnifying eyepiece Relay system re-inverts image to a real one Image is focused using eye piece Indication of use: Small pupils Uncooperative children Patients intolerant to bright illumination 9

10. Instrumentation Headpiece illumination condensing oculars Convex lenses in the eyepieces of +2.00 D to relax the accommodation and view aerial image Condensing hand held lens ( +30D; +20D; +14D) Scleral depressors 10

11. Types HEAD MOUNTED SPECTACLE MOUNTED 11

12. Condensing Lenses Three types Biconvex Plano convex Aspheric Two different curved surfaces - to avoid spherical aberration Steeper curvature faces the examiner + 20 ,+30 , +14 D 12

13. Properties of Condensing Lenses Dioptric power 30 D 20 D 14 D Magnification Field Stereopsis Focal Length 2 60 o ½ normal 3.3 cm 3 37 o ¾ normal 5 cm 4 30 o 1 normal 7 cm 13

14. Scleral indentor For viewing the fundus periphery and oral region Suggested by Trantas in 1900- used nail Thimble depressor – Schepens Articulated scleral depressor Hand held scleral depressor 14

15. OPTICS OF INDIRECT OPHTHALMOSCOPY 15

16. Principle of indirect ophthalmoscope To make the eye highly myopic by placing a strong convex lens in front of patients eye The emergent rays forms a real inverted image between the lens and observer’s eye 16

17. Principle of binocular indirect ophthalmoscope 17

18. Optical system of BIO Binocularity is achieved by artificially reducing the observer’s IPD to approximately 15mm by the help of prisms/mirrors 18

19. Field of illumination More in myopia and less in hypermetropia as compared to emmetropia 19

20. Image formation EMMETROPIA MYOPIA HYPERMETROPIA 20

21. Emmetropia Emmetropic eye, rays from fundus are parallel, brought to a focus by the condensing lens Image formed at the principal focus of the lens Hence, size of image remains the same, no matter the position of lens. 21

22. Myopia Rays are convergent Image formed in front of the eye Final image by condensing lens within its own focal length Image is smaller when lens is nearer to anterior focus of the eye and larger when away 22

23. Hypermetropia Rays divergent and appear to come from behind the retina Image by condensing lens in front of its principle focus Image is larger when lens is nearer to the anterior focus of the eye and smaller when away. 23

24. Relative position of images In Emmetropia: - at the principal focus In Myopia: - Nearer to the lens than its principal focus In Hypermetropia: - Farther away from the principal focus 24

25. Factors affecting Field of View Patient's pupil size Power of the condensing lens Over all size of the condensing lens Refractive error (very small amount ) Distance the condensing lens is held from the patient's eye 25

26. Image characteristics Real, inverted and magnified Magnification depends on: - Dioptric power of the convex lens Position of lens in relation to the eyeball Refractive state of the eyeball 26

27. Procedure for indirect ophthalmoscopy Explain the procedure At least one attendant in examination room Make the patient feel comfortable Dilate pupils Darken the room Keep both eyes open 27

28. Procedure Adjust head band Eye pieces are as close to the pupil as possible (+2.0D in eye piece to compensate for the accommodation) Eye pieces should be perpendicular to pupillary axis 28

29. Adjust IPD Face a wall approximately 40 cms away, and adjust the illumination mirror such that the illumination field is vertically centralized to the observation ports

30. Positions Sitting position First Opacities may move out of the way in one position Change in retinal folds and expose retinal breaks which may not be otherwise visible Lying down position Easier for the patient Examination of periphery 30

31. Holding of condensing Lens Hold the condensing lens with non-dominant hand Dominant hand for multiple functions which requires dexterity like: - Keeping patients eyelids apart when necessary Using scleral depressor Adjusting the knobs of the ophthalmoscope AND MOST IMPORTANT SKETCHING FUNDUS DETAILS 31

32. Holding of Condensing lens Condensing lens grasped between bulb of thumb & tip of flexed index finger Middle finger holds one lid & thumb of other hand, the other lid Flex the wrist Most lenses are coded either with a white or silver ring, this side is placed toward the patient's eye 32

33. Procedure Start with minimum intensity Brief examination in sitting position from disc to equator Then patient lies down for detailed fundus examination and fundus charting 33

34. Examination Technique Both eyes of the patient should be open Throw light into the patient’s eye from an arm’s distance and observe for red reflex Interpose the condensing lens, with more convex side towards the examiner in the path of the beam of light, keeping a watch on the reflex close to the patient’s eye Slowly move the lens away from the eye till the image of the retina is clearly seen This is usually at the focal length of the lens 34

35. Examination Technique Move around the head of the patient to examine different quadrant Stand opposite the clock hour to be examined Ask the patient to look in extreme gaze to see the more periphery of the fundus Correct position of the eye: - Provide a target like patient’s thumb Non seeing eye: - proprioceptive impulses 35

36. Examination Technique Maintain a common line of sight by imagining that the fundus under examination, the centre of the patient’s pupil, the centre of the condensing lens and the examiners visual axis are all connected by an imaginary line . 36

37. Peripheral Fundus Shape of pupil and retro-illumination changes with change in gaze With this changes the amount and extent of peripheral retina seen 37

38. Fundus periphery Stereopsis is good when the images of the observer’s both pupil are far apart in the patient’s pupil During examination of fundus periphery, the patient’s pupil appears elliptic to the observer The observer’s view becomes monocular 39

39. Adjustment of light source While viewing fundus periphery much of the light is imaged outside the patient’s pupil The light source should be adjusted to bring the image of the light source inside the elliptic pupil 40

40. Using variable pupil function and altering the covergence angle of right and left image steropsis can be achived . 41

41. Fundus Periphery Eye is rotated in the direction of the quadrant to be examined Stand 180° away from the quadrant to be examined Observer should align his head with the long axis of the pupil. This will allow wider exit pupil for stereoscopic view Use scleral indenter 42

42. Change the patients gaze in 20 - 30° increments Observe all the parts of Retina (‘Sweeping of the fundus’) 43

43. Alternative Method Examination of both eyes at the same time For quick comparison of both peripheral fundi pigmentation and appearance 44

44. Problems and Solutions Tilt the BIO lens to remove undesirable reflections Adjust the illumination slightly higher or lower than center Moving closer towards the image will magnify the view but decrease the field Moving away from the image will increase the field of view but decrease the magnification 45

45. Scleral indentation 46

46. Scleral Indentation Adjunct to see the peripheral/anterior parts of the fundus Dynamic examination (Rolling of lesion) Usually worn in middle finger of dominant hand Better control by holding between thumb and index finger 47

47. Dynamic Examination Differentiate between a retinal tear and hemorrhage Hemorrhage will become elevated with indentation, holes will either gape open, look larger and/or appear darker with a surrounding edematous (white) cuff. 48

48. Scleral Indentation Place the tip of indenter on the skin on eyelid tarsal plate over the area of sclera to be indented While examining upper fundus Close the eyelids Apply depressor tip to the upper lid at the upper edge of the tarsus Ask the patient to open the eyelids and look up Depressor slides easily under the orbital margins 49

49. Scleral Indentation For 3 or 9 o’clock : - Sometimes necessary to apply pressure over the bulbar conjunctiva directly Topical anaesthesia Depressor should be introduced and removed from the conjunctival sac very slowly Perform this examination last as proparacaine may cause corneal epithelial oedema Use a 70% isopropyl alcohol swab to clean the depressor 50

50. Scleral Indentation Use indenter tangentially to the globe, with gentle pressure If used perpendicularly, causes pain and squeezing of eyelids 51

51. Scleral Indentation Axis of the indenter along the meridian of the globe-This ensures tip more likely to be in proper meridian If introduced obliquely- tip may not be in the observed meridian 52

52. Technique Shine your BIO in the pupil and observe the red-orange reflex Have the patient look in the direction where you have placed the depressor. Apply a light amount of pressure with the depressor. If the depressor is properly aligned along the correct axis, a darkening or change in the quality of the red- orange reflex is seen Insert the condensing lens and adjust the illumination such that the light shines into the eye in the direction of the depressor 53

53. Technique Again apply a light amount of pressure with the depressor. Pay attention to the lower part of the condensing lens The examiner should see an elevated possibly "grayish mound" of the indented retina. So called “ Mouse under the Blanket” phenomena Indicates that the indenter is in correct position 54

54. Remember while indentation Indentation beyond the Tarsal Plate Ora Serrata is 7mm from Limbus . Indenting too anteriorly is useless counter productive If mound of fundus not seen on indentation, its in another location 55

55. Remember while indentation Don’t apply too much pressure Be careful in patients who have IOL specifically AC IOL or Iris Supported IOL Procedure may be painful in patients with high IOP 56

56. Scleral indentation Retinal breaks in detached retina without indentation Enhanced visualization of breaks with indentation

57. Contraindications for Scleral Indentation Recent or suspected penetrating injuries Orbital injuries Intraocular surgery within 8 weeks Correct indentation is not believed to enlarge retinal holes or cause RD 58

58. Charting 59

59. Charting Best Chart Papers are the ones Avoids Glare Photographic reproducibility better Clipped on rigid board which rests on patient’s chest Oriented upside down so that 12 o’ clock on the chart is towards patients feet 60

60. Fundus drawing Place chart upside down Draw what you see Technique Vitreous opacity

61. Amsler’s Chart 3 Concentric Circle Innermost – Equator Middle – Ora Serrata Outermost – Pars plana Radial lines to describe the location of fundus finding in clock hours Posterior pole – in the 1 st circle 62

62. Orientation Ora serrata on chart has a larger circumference than the equator, while actually the equator has a greater circumference Centre of the chart: Optic nerve [O] Fovea [+] 63

63. Colour Coding 64

64. 65

65. Anatomical Landmarks Ora – Dentate processes Ampulla of vortex veins (red Octopus) – approximately at equator 1,5,7,11 o’clock Long post. ciliary vessels & nerves – 3 & 9 o’clock Dividing line between anterior and posterior portions of the fundus : Equator 66

66. 67

67. Units of Measurement Calculations in mm : 1 DD = 1.5 mm Elevation: +3DD = 4.5 mm Distance between each clock hour in the eye Ora serrata : 3 DD Equator : 6 DD Total distance from the Equator to Ora serrata : 4 DD (6 mm) Equator to Macula : 6 DD (9 mm) 68

68. Procedure Enter patient details Chart placed with the 12-00 meridian facing patient’s feet at 6-00 meridian facing patient’s chin Stand on the same side as the eye being examined Stand 180 from the site to be observed First observe: Disc, Macula and Post. pole Trace the major blood vessels as far anteriorly as possible 69

69. Procedure Whatever meridian we see, its as if we are standing at the ora at that meridian and looking at the post. Pole Examine a meridian standing 180 degrees away Constantly check orientation by removing the condensing lens to verify the position of the eye Draw exactly what is seen Repeat the examination using scleral indentation Look for fundus landmarks Start drawing from disc towards periphery 70

70. Disadvantages of Indirect Ophthalmoscopy Direct Ophthalmoscopy easy to learn than indirect Inversion of image with indirect method of ophthalmoscopy- requires some practice to overcome INSTRUMENT DIPLOPIA in learners who accommodate on inverted image and necessarily converge as well causing homonymous diplopia Less magnification Patient is more uncomfortable with intense bright light 71

71. Photic Damage to the Retina Feared if Indirect Ophthalmoscope used at full intensity for prolonged time In experimental animals it is seen that damage to outer segment of the photoreceptors and RPE cells does take place Heat is an important element in this damage Damage to macula occurs when light thrown more than 7 min 72

72. Photic Damage to the Retina In clinical conditions: - Light is seldom focused - same area for more than 30-60 seconds Patient’s slight but constant eye movements These factors protect against accumulation of heat Avoid examining macula for prolonged period with full intensity of indirect light Caution is to be exercised while examining patient’s with high fever since difference of 2° or 3 ° C may sensitize the RPE and retina to photo-damage 73

73. Filters Green light – Nerve fibre layer, Blood vessels, microaneurysms Red light – Subtle pigmentary abnormalities Blue light – Angioscopy Yellow filter – Reduces photophobia

74. Cleaning And Sterilizing Your Condensing Lens Clean the lens using contact lens cleaner and warm tepid water, NOT HOT WATER. Then dry with a soft lint free cloth or paper towel. Never autoclave or boil a condensing lens. Place the lens completely in 3% hydrogen peroxide solution 2% Glutaraldehyde aqueous solution 20-25 mins Sodium Hypochlorite 1:10 parts 10 mins Pure 70% Isopropyl Alcohol for 5-10 minutes. 75

75. INDIRECT OPHTHALMOSCOPY Binocular view Use of condensing lens captures peripheral rays Wide field of view 25 ° or more depending on lens

76. INDIRECT OPHTHALMOSCOPY Check correct interpupillary distance Beam in centre of viewing frame Lens flat surface facing the patient Patient asked to move eyes and head into optimal positions for examination

77. NORMAL FUNDUS Pink optic disc with cup in centre Arteries lighter in colour and narrower than veins Red background due to choroidal vessels and retinal pigment epithelium Central macula

78. The Indirect Ophthalmoscope Gullstrand Indirect Ophthalmoscope ca. 1910 George T. Timberlake, Ph.D. Department of Ophthalmology University of Kansas Medical Center

79. If the retina could light up…. Emmetropic eye Image of retina on distant surface GTT 04 Fundamental Principle of the Indirect Ophthalmoscope

80. Ophthalmoscopic lens Aerial image of retina Fundamental Principle of Indirect Ophthalmoscope GTT 04

81. Viewing the aerial image with a magnifier GTT 04

82. Allvar Gullstrand Swedish Ophthalmologist 1862 - 1930 Professor of Physical & Physiological Optics, University of Uppsala Nobel Prize 1911 for work on optics of eye First “reflex free” ophthamoscope GTT 04

83. FIRST ATTEMPT AT BINOCULAR VIEW Obs. L eye Obs. R eye S’s eye Combine L and R eye views Observer’s eyes have to be too close

84. GTT 05

85. IMAGE ORIENTATION MAGNIFICATION FIELD OF VIEW

86. TOP VIEW

87. GTT 04

88. GTT 04

89. SUMMARY Draw a simplified diagram of the optics of the binocular indirect ophthalmoscope. Illumination planes Pupil planes Retinal image planes Be able to explain: Image orientation Field of view Magnification

90. BIO MAGNIFICATION M aerial image = P eye P lens

91. Indirect ophthalmology Condensing lenses

92. Slitlamp biomicroscopy Goldmann triple-mirror lens Image is upside down View of peripheral fundus

93. History of ophthalmoscope Mery in 1704 made first ophthalmoscopic observation of a normal fundus in a drowning cat Cumming and Brucke in 1846 explained the principles of ophthalmoscopy 102