B-SCAN IN OPHTHALMOLOGY.pptx

its all about use of Bscan in eye diseases

1. B-SCAN IN OPHTHALMOLOGY Dr. Amresh Kumar Associate Professor Department Of Ophthalmology SBMCH, Hazaribag , Jharkhand

2. B-scan or brightness modulation scan provides two dimensional images of a series of dots and lines. B-scan provides the topographic information of shape, location, extension , mobility, and gross estimation of thickness of the tissue 2 dr amresh kumar

3. History It was first used in the field of ophthalmology by Mundt and Hughes . Oksala et al reported the sound velocities in the various components of the eye Baum and Greenwood came up with two dimensional, immersion scan First commercially available B scan was developed by Coleman et al in seventies The importance of the instrument and standardization of technique was emphasised by Karl Ossoinig 3 dr amresh kumar

4. Ultrasonography is used for Biometry ( Ascan ) for axial length and corneal thickness measurement. Standardized Ascan (diagnostic) for the echostructure assessment. It is a part of the Bscan in most of the contemporary machines with cross vector facility. Diagnostic Bscan (two dimensional) has to be coupled with the standardized Ascan to arrive at a correct diagnosis. Doppler ultrasonography is especially important in vascular lesions with different blood flow rates . Ultrasound biomicroscopy 4 dr amresh kumar

5. background 1-2 MHz :abdominal ultrasound 8-10 MHz :ophthalmic ultrasound (b scan) is best for posterior segment 35-80 MHz: ultrasound biomicroscopy best for cornea and anterior segment 5 dr amresh kumar

6. B mode(brightness) - Principle 2 D acoustic section An oscillating focussed sound beam is emitted, passing through the eye and imaging a slice of tissue , the echoes of which are represented as multitude of dots that together form an image on the screen. Stronger the echo, brighter the dot. 6 dr amresh kumar

7. The probe Bscan probes are thick, with a mark They emit focussed sound beam at a frequency of 10MHz. The mark on the probe indicates beam orientation Area towards which the mark is directed appears at the top of the echogram on display screen. Probe tip: the white line on the far left side of display Echoes to right side of this line –ocular structures opposite the tip 7 dr amresh kumar

8. Mostly the Bscanning is done transpalpebrum with slightly increased overall gain. Bscan probe can also be put directly on the anaesthetized globe after applying eye speculum; Pictures obtained with Bscan probe are two dimensional as compared to Ascan probe. 8 dr amresh kumar

9. To obtain high quality B scan pictures Ensure that Lesions are placed in the center of the scanning beam The beam is directed perpendicular to the interfaces at the area of interest Use lowest possible decibel gain consistent with the maintenance of adequate intensity to optimize the resolution of images. 9 dr amresh kumar

10. B scan pictures can be obtained by axial , transverse and longitudinal sections. axial axial longitudinal transverse 10 dr amresh kumar transverse

11. axial section The patient fixates in the primary gaze Probe is placed on the globe and directed axially towards the posterior pole. Depending on the clock hour location of the marker, axial-horizontal, axial-vertical and axial oblique pictures are obtained. These sections demonstrate lesions at the posterior pole and the optic nerve head. Marked attenuation of the sound beam by the crystalline lens not suitable for macular thickness measurement. The lens is avoided by placing the probe at the limbus . 11 dr amresh kumar

12. Transverse section: Transverse section: The mark is kept parallel to the limbus and probe is shifted from limbus to the fornix and also sideways. Produces a circumferential slice through several meridians This scan gives the lateral extent of the lesion. 12 dr amresh kumar

13. Longitudinal section: Longitudinal section: The mark is kept at right angle to the limbus towards the centre of cornea Helps in determining the antero -posterior limit of the lesion. Best to determine attachment of membranes to optic disc 13 dr amresh kumar

14. During the procedure the probe is moved from limbus to fornix in different clock hour meridians and the picture seen is of diagonally opposite meridian as follows: 14 dr amresh kumar

15. Probe can be moved antero -posteriorly as well as sideways. Patient is instructed to fix the gaze so that the probe is perpendicular to the area being examined 15 dr amresh kumar

16. For macular screening , the four basic Bscan probe positions that allow perpendicular sound beam exposure to the macula are horizontal axial, vertical transverse, longitudinal and vertical macula approaches. 16 dr amresh kumar

17. With contact type of scanning there is a dead zone of about 7.5mm adjacent to the probe , so that the lesions in this region are missed. To visualize this area, one can keep the probe on the opposite side at right angle or use immersion scan technique. dead zone 17 dr amresh kumar

18. Topographic ultrasonography To determine the location, shape and extent of the lesion A transverse scan to determine the maximal height and lateral basal dimension of the lesion A longitudinal scan is done to determine the anterior to posterior topographic feature of the lesion 18 dr amresh kumar

19. Quantitative ultrasonography Reflectivity : height of the spike on Ascan Internal structures: Homogenous : little variation in spike Heterogenous : marked variation in spike A scan probe calibrated for tissue sensitivity Sound directed perpendicular to the lesion Sound attenuation (acoustic shadowing): for calcification, foreign bodies, bones 19 dr amresh kumar

20. Kinetic ultrasonography Motion of a lesion Within a lesion Mobility , vascularity and convection movement Mobility Change in gaze PVDs, RDs and choroidal detachments all exhibit their own distinctive pattern of movement Used in conjunction with colour Doppler instruments 20 dr amresh kumar

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22. Use of bscan : Some of the common eye conditions where diagnostic ultrasonography is helpful are: Dense cataract vitreous haemorrhage , leucokoria vitritis / endophthalmitis painful blind eye before penetrating keratoplasty intraocular tumors oculo -orbital trauma postoperative cases 22 dr amresh kumar

23. Dense cataract Do bscan and look for retinal detachment(RD), intraocular tumor with calcification, posterior staphyloma , vitreous haemorrhage , asteroid hyalosis , optic nerve head cupping, abnormal growth over optic nerve head or axial length disparity. 23 dr amresh kumar

24. Use of bscan In vitreous haemorrhage , on echoevaluation one may pick up retinal tear with detachment, disciform degeneration, melanoma, fibrovascular fronds with tractional RD or subhyloid haemorrhage . The cause of leucokoria whether due to retinoblastoma, PHPV, Coat's disease, Retinopathy of prematurity or old haemorrhage can be deduced. 24 dr amresh kumar

25. Use of bscan In vitritis / endophthalmitis , it helps in ruling out foreign body (FB) and rupture of intraocular cyst and helps in assessing the response to treatment. In a painful blind eye, it is indicated to rule out uveal melanoma, old RD with chronic uveitis , intraocular/ subretinal cyst, lens dislocation, failed RD surgery, inflamed phthisical eye, e.t.c . 25 dr amresh kumar

26. Use of bscan Patients planned for penetrating keratoplasty with opaque anterior segment. Patients with clear media where on indirect ophthalmoscopy suspicious lesions suggestive of intraocular tumors like choroidal melanoma, haemangioma , metastatic carcinoma, osteoma , etc are seen. Orbital screening should be performed in patients with abnormal choroidal folds and posterior scleritis . 26 dr amresh kumar

27. Use of bscan In oculo -orbital trauma, it is imperative to look for sclerochoroidal rupture with RD, intraocular/orbital FB, lens displacement, optic nerve avulsion and orbital haemorrhage . In postoperative cases to assess endophthalmitis /toxic anterior segment syndrome, lens fragment/ intraocular lens(IOL) displacement into the vitreous cavity, choroidal detachment/ haemorrhage , status of retina post RD surgery, etc. 27 dr amresh kumar

28. Echodescription of common intraocular conditions: 28 dr amresh kumar

29. Vitreous floaters Appear as one or more echo dots of less brightness in the mid /posterior vitreous cavity They show mobility with after movement display on Bscan . On Ascan , these echodots have extremely low to low reflectivity (2-20%) and to appreciate them better overall gain may be increased by 56db. 29 dr amresh kumar

30. Vitreous haemorrhage They appear as multiple fine echo opacities dusting the vitreous body which do not extend beyond the posterior vitreous border. They are usually attached to the retinal surface They may be fresh, resolving, organizing or organized with membrane formation. To pick up fresh vitreous haemorrhage , the overall gain can be increased by 10 db. 30 dr amresh kumar

31. In older haemorrhage , echodots are denser show higher reflectivity (up to 60%) on Ascan . In resolving vitreous haemorrhage , echodots on Bscan show decrease in brightness and numbers. Old organized vitreous haemorrhage can result in vitreous-membrane formation showing echogenic lines on Bscan mimicking RD The attachment of the echomembrane on/ upto the optic nerve head and Quantitative echography II help to differentiate RD from vitreous membranes 31 dr amresh kumar

32. Subhyaloid haemorrhage Subhyaloid haemorrhage is situated typically at the posterior pole between the anterior surface of retina and posterior vitreous face. It may be fluid in nature or may get organized. Sometimes an organized old pre-retinal haemorrhage may be seen in all the quadrants of the globe. 32 dr amresh kumar

33. endophthalmitis The inflammatory cells are seen dotlike on Bscan , These are multiple, scattered diffusely or may be localised to the anterior, mid or the posterior one third of the vitreous cavity depending on the etiology. 33 dr amresh kumar

34. On A scan, these dot like opacities show low to medium reflectivity (10-60%). It is not possible to differentiate vitritis from vitreous haemorrhage in still pictures unless clinical details are available. These inflammatory cells organize very rapidly to form vitreous membranes and therefore frequent examinations should be performed. 34 dr amresh kumar

35. Asteroid Hyalosis It is characterized clinically by presence of calcium crystals embedded in an amorphous matrix on Bscan It appears as multiple, densely packed, homogeneously distributed echodense dots of medium to high reflectivity (50-100%) These are usually localized to the core of vitreous body. One may find clear retrovitreal or pre-retinal space 35 dr amresh kumar

36. Posterior vitreous detachment (PVD): PVD is seen as echogenic membrane concentric to the globe, infront of the retinochoroidoscleral complex with clear subvitreal space . It may be small, interrupted, peripheral or continuous and total. If lined with red blood cells its echo density increases. On A scan, the reflectivity of this membrane is low if the PVD is thin but it may be high if it is thick and lined with red blood cells. PVD usually does not show attachment to the optic nerve head. 36 dr amresh kumar

37. Retinal detachment Retinal detachment means separation of neurosensory retina from the pigmentary retina. It may be total/subtotal, localized/peripheral or fresh/old with proliferative vitreoretinopathy (PVR) changes. 37 dr amresh kumar

38. Retinal detachment On Bscan , RD appears as echogenic dense membrane, biconvex or biconcave with 100% attachment at the optic nerve head (ONH) and 90-100% reflectivity on Ascan . Attachment at ONH is not seen in localized, peripheral RD where membrane is visible only in a single quadrant. In uncomplicated cases, there is a clear space between the detached retina and the ocular coat spike indicating transudative nature of the subretinal fluid. 38 dr amresh kumar

39. Fine echodots may also be seen in the subretinal space indicating the presence of haemorrhage or debris. In PVR cases, vitreous body shows debris dots or membrane formation depending upon its grade and cystic degeneration may be present in an old RD. After movement if present is suggestive of fresh RD. In rhegmatogenous RD, retinal tears especially operculated tears/ giant tears and even the trickle of vitreous haemorrhage from the break site into the vitreous cavity may be picked up. 39 dr amresh kumar

40. In tractional RD , fibrovascular frond within the vitreous cavity or along the vitreous face may be seen. This frond when exerts tractional force on the retina, produces tent like elevation from the retina as an echogenic membrane which may be localized or extensive enough to become total. It does not show after-movement and vitreous cavity may show evidence suggestive of old haemorrhage . On Ascan this thick membrane produces 100% reflectivity . At times thick vitreous may be difficult to differentiate from RD as it may have an attachment to the ONH and Quantitative echography II may be used to differentiate the two 40 dr amresh kumar

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42. Scleral Explants Scleral Explants are used in rhegmatogenous RD surgeries where buckle or sponge is applied to indent the globe. On Bscan they appear as echogenic spots with the globe indentation towards the vitreous body and echolucent spot (shadowing) behind the scleral explant . The explant shows high reflectivity on Ascan . Silicone buckle is less echodense in comparison to the sponge. Silicon buckle sponge Scleral erosion 42 dr amresh kumar

43. Vitreous expanders Vitreous expanders like silicone oil or perfluorocarbons may be seen in operated RD cases. Emulsified silicone oil produces marked sound attenuation hindering the visualization of posterior segment. It also results in a larger vitreous cavity which is relatively echofree . Perfluorocarbons on the other hand show multiple, highly reflective liquid bubbles in the posterior vitreous Emulsified silicone oil Perfluorocarbons 43 dr amresh kumar

44. Choroidal detachment Choroidal detachment is usually in the periphery and may be localized or total. It is seen as dome shaped elevation with clear sub choroidal space on Bscan and 90-100% double peaked tall spike on Ascan . There is none or very little after movement on kinetic echography . 44 dr amresh kumar

45. Choroidal detachment In cases with impending expulsive haemorrhage or traumatic choroidal detachment, the sub choroidal space shows haemorrhage as multiple dot like opacities on Bscan . There may be two or more domes which may meet in the vitreous cavity to form kissing choroidals . 360 degree detachment shows pathognomic scalloped appearance 45 dr amresh kumar

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47. Retinal tear Retinoschisis : Moderately elevated thin membrane shaped echo Retinal tear with free superior end Vitreous attached to the tear tear 47 dr amresh kumar

48. Intraocular tumors Intraocular tumors which commonly require Bscan evaluation are retinoblastoma, choroidal melanoma, hemangioma , metastasis, diktyoma and Osteoma Bscan helps in measurement of tumour dimensions, differentiation , extrascleral extension, size , assessing tumour growth or regression help in distinguishing solid from cystic lesions 48 dr amresh kumar

49. Retinoblastoma Retinoblastoma is seen as a solid tumor arising from the retinal layer obliterating the vitreous cavity. Calcification within the tumor mass is typical of retinoblastoma. There may be shadowing effect behind the lesion in the orbital mass. Concomitant RD may be sometimes present. 49 dr amresh kumar

50. Retinoblastoma On A scan, spikes with moderate internal reflectivity may be seen but in presence of necrosis and calcification, highly reflective, irregular spikes are observed. Sound attenuation is moderate to high. The globe is usually normal in size except in glaucomatous stage when it becomes enlarged, 50 dr amresh kumar

51. OSTEOMA 51 dr amresh kumar

52. In persistent hyperplasic primary vitreous , the globe size may be smaller and the vitreous cavity shows persistence of the primary vascular system seen as echo membranous track from optic nerve head to the back of the lens 52 dr amresh kumar

53. Retinopathy of prematurity Retinopathy of prematurity is characterised by multiple vitreous membranes and RD in the periphery. The size of the globe may be smaller in these cases. 53 dr amresh kumar

54. Coat's disease In Coat's disease there is unilateral involvement and there may be presence of an exudative RD with turbid subretinal fluid or cholesterol crystals in the subretinal space. 54 dr amresh kumar

55. Choroidal naevus /melanoma appears as a small dome shaped, localized, solid lesion, elevated from the ocular coats with low to medium reflective Ascan spike (40-60%). Collar stud pattern/ mushroom appearance Regular internal structure, acoustic shadowing, internal vascularity Tuberculoma may have a similar appearance on Bscan . Collar stud pattern/ mushroom pattern Tumour with RD 55 dr amresh kumar

56. ruptured globe In a ruptured globe with low intraocular pressure, there may be scleral dehiscence with vitreous haemorrhage , vitreous/ uveal tissue prolapse or vitreous haemorrhage with RD. Scleral dehiscence usually occurs at the site of extraocular muscle insertion and may be concentric to the limbus. In cases of small scleral rupture, a trickle of haemorrhage into the vitreous cavity is noticed on Bscan . 56 dr amresh kumar

57. haemophthalmos Hyphaema , vitreous haemorrhage with choroidal haemorrhage and scleral rupture with orbital haemorrhage may be seen in combination and the condition may appear as haemophthalmos . Black eye (lid haemorrhage ) may coexist with it. 57 dr amresh kumar

58. Posteriorly dislocated crystalline lens into the vitreous cavity It is seen as a biconvex body which may be mobile or fixed. Lens fragment in vitreous usually produces vitritis . The intraocular lens in vitreous cavity appears like a FB and shows high reflectivity and shadowing effect behind it. intraocular lens crystalline lens Lens fragment 58 dr amresh kumar

59. Phthisis bulbi Phthisis bulbi The globe is small, soft, deshaped and There is thickened retinochoroidal complex . Intraocular calcification or bone formation may occur in choroidal layer in long standing cases which is better appreciated on decreasing the gain by 15-20db. Retro globe shadowing may also be visible. 59 dr amresh kumar

60. IOFB IOFB are seen as echodense spots with a 100% reflectivity on Ascan spike irrespective of the nature of the FB and ultrasonography enables its exact sizing and localization. Shadowing effect is usually seen. Decreasing the gain on the machine by 10db helps in differentiating it from dense blood clot and lens fragment. 60 dr amresh kumar

61. IOFB Spherical FB like gunshot pellets, have an anterior and posterior surface and between them there are multiple internal reverberations/echoes . These echoes are seen as echogenic opacities with a wedge shaped trail of spikes . The trail disappears on decreasing the overall gain of machine but the initial echodense spot remains as such 61 dr amresh kumar

62. optic nerve evaluation general topography ,relationship to structures , optic disc anomalies and alteration in contour of the globe the subarachnoid space surrounding optic nerve appears as echoluscent crecentric or circle around the nerve called ‘ DOUGHNUT SIGN 62 dr amresh kumar

63. Macular edema 63 dr amresh kumar

64. Retinal coloboma is a congenital abnormality seen in the inferonasal quadrant as defect in the retinochoroidal layer of the globe on Bscan . Optic disc coloboma : If the coloboma involves the ONH region, there is absence of ONH . Optic disc coloboma 64 dr amresh kumar

65. Posterior staphyloma It appears as a sudden bowing backward of the globe with thinning of the retinochoroidal layer. It is usually seen at the posterior pole and the axial length of the globe is increased , indicating axial myopia. There may be presence of vitreous debri . Posterior staphyloma 65 dr amresh kumar

66. Post operative endophthalmitis In endophthalmitis there is severe vitritis and exudation in the vitreous cavity. Bscan is useful in evaluating the response to intravitreal injection in endophthalmitis 66 dr amresh kumar

67. Cysticercosis It is common in vitreous cavity, subretinal space and sub conjunctival space Bscan reveals a well defined cystic lesion with clear contents and a hyperechoic area suggestive of scolex . Serial echography helps in follow up scolex Cystic lesion 67 dr amresh kumar

68. Posterior scleritis : T-sign collection of fluid in sub tenon space T-Sign in posterior scleritis 68 dr amresh kumar

69. Reverberation artefacts insufficient coupling fluid entrapment of air between the probe and eye display of bright echoes representing multiple signals ANGLE OF INCIDENCE ARTEFACT 69 dr amresh kumar

70. Thank you 70 dr amresh kumar

71. UBM 27-Dec-12

72. Ciliary body tumor 27-Dec-12

73. Iris tumor 27-Dec-12

74. Tumor involving the cornea UBM shows that the tumor ( T) is superficial and that Bowman’s membrane is intact over the cornea 27-Dec-12

75. Tumor involving the cornea UBM shows deep involvement of all corneal layers (T) 27-Dec-12

76. Iridociliary cyst 27-Dec-12

77. Peter’s anomaly 27-Dec-12

78. Iridodialysis 27-Dec-12

79. Cyclodialysis 27-Dec-12