This document provides an overview of ultrasound principles and techniques for ophthalmic examination. It discusses the history of ultrasound in ophthalmology and describes A-scan, B-scan, and UBM modalities. Examination techniques for evaluating the globe, orbit, and various ocular structures are outlined. Indications for diagnostic ultrasound include evaluating the lens, vitreous, retina, tumors, and more. Clinical examples of pathologies visualized by ultrasound are also presented.

1. USG
DR DIWA HAMAL LAMICHHANE
3rd YEAR RESIDENT
DEPT OF OPHTHALMOLOGY

2. Outline
 Introduction
 History
 Ultrasound Principles and Physics
 A Scan
 B Scan
 UBM
 Examination Techniques For The Globe
 Examination Techniques For The Orbit
 Indications

3. Introduction
 One of the most useful non invasive diagnostic
techniques of intraocular & orbital evaluation involves
pulse-echo technology

4. History
 First used in ophthalmology in 1956 by
Mundt & Hughes - time amplitude-mode
(A-scan)
 Oksala & associates (Finland, 1957) -
published data regarding the sound
velocities of various components of the
eye
 In 1958, Baum & Greenwood developed
two dimensional (immersion) brightness-
mode (B-Scan) ultrasound instrument for
ophthalmology

5. History..
 In 1960s, Ossoinig (Austrian) -
 Developed the first standardized A-scan instrument,
the Kretztechnik 7200 MA (contact B-scan added
later)
 Devised meticulous examinations techniques
 Purnell in 1972, Coleman & associates - first
commercially available immersion B-scan instrument
 Bronson (1974) - contact B-scan machine - portable &
easy to use

6. Ultrasound Principles and
Physics
 Ultrasound wave shows the
properties of refraction &
reflection
Echo-
Reflected portion of the wave
produced by acoustic interfaces
that are created at the junction of
two media that have different
acoustic impedances
Acoustic impedance
= sound velocity × density

7. Ultrasound Principles and
Physics
Affected by many factors-
 Angle of sound incidence
 Size, shape & smoothness
of acoustic interface
 Absorption (higher frequency
> lower frequency)
 Scattering
 Refraction

8. Pulse-Echo System..
Probe / Transducer
Pulser
Receiver
Amplifier
Display

9. Ultrasound Principles and
Physics
Electrical
energy
converted to
sound energy
sound waves
strike
intraocular
structures
reflected back to
the probe
&converted into
an electric signal
signal is
subsequently
reconstructed as
an image on a
monitor
used to make a dynamic
evaluation of the eye or can be
photographed to document
pathology

10. Ultrasound Principles and
Physics
 Sound is emitted in a
parallel, longitudinal
wave pattern, similar to
that of light.
 Propagates as a
longitudinal wave that
consists of alternating
compressions &
rarefactions of molecules
as the wave passes
through a medium

11. Ultrasound Principles and
Physics
 Ultrasound - must have a frequency of greater than
20,000 oscillations per second, or 20 KHz
 Frequencies used in diagnostic ophthalmic ultrasound
range from 8 – 15 MHz.
 Inaudible to human ears.
 The higher the frequency of the ultrasound, the shorter
the wavelength good resolution of minute ocular and
orbital structures.

12. Ultrasound Principles and
Physics
 A direct relationship exists between wavelength & depth
of tissue penetration (the shorter the wavelength, the
more shallow the penetration).
 Ultrasound probes used for ophthalmic B-scan are
manufactured with very high frequencies of about 10
million oscillations per second, or 10 MHz.
 Recently, high-resolution ophthalmic B-scan probes
(UBM) of 20-50 MHz have been manufactured that
penetrate only about 5-10 mm into the eye for incredibly
detailed resolution of the anterior segment.

13. A - Scan
 It is one dimensional acoustic display in which echoes
are represented as vertical spikes from a baseline.
 Spacing of spikes depends on the time it takes for the
sound beam to reach a given interface & for it’s echo to
return to the probe.
 The time between two echo spikes converted into
distance by knowing sound velocity of media
 Height of spike indicates the strength(amplitude) of echo

14. A - Scan

15. B-Scan Echography
 Produces a two-dimensional acoustic section by using
both the vertical & horizontal dimensions of the screen to
indicate configuration & location
 Requires a focused, narrow sound beam
 An echo is represented as a dot
 Strength of echo represented by brightness of dot
 Factors affecting the display-
 angle of the scanning transducer  the area scanned
 speed of the transducer oscillation  frame rate
 gray scale  echo intensity differentiation

16. B - Scan

17. B-Scan Echography
 Interpretation is based upon three
concepts -
1. Real time
  32 frames/sec
 dynamic examination
2. Gray scale
 stronger the echo, brighter the display
3. Three-dimensional analysis
 most difficult concept to master
 mental three-dimensional construct from
multiple two-dimensional images

18. Examination Techniques For The Globe
 Positioning the patient
 Topical anaesthesia
 Probe & it’s marker
 Probe Face - always represented by the initial line on the
left side of the echogram
 Fundus - represented on the right side of the echogram
 The upper part of the echogram corresponds to the portion
of the globe where the probe marker is directed
 The center of the screen corresponds to the central portion
of the probe face

19.  Methylcellulose - A coupling medium
 Probe - Placed directly on the globe
 Probe Orientations
 Transverse & Axial Scans
 Horizontal
 Vertical
 Oblique
 Longitudinal Scans
Direction Of Marker
Nasal
Superior
Superior
Toward center of
Cornea & Meridian
being examined
Examination Techniques For The Globe

20. Probe positioning
 Transverse probe positions
 Longitudinal probe positions
 Axial probe positions

21.  Sweeps across the
meridian
 The Designation of the
Transverse Scan
e.g.. transverse scan
of the 12- o’clock
meridian
Transverse Scan

22.  Keep marker
perpendicular to the
limbus, sweeps along
the meridian.
 Anteroposterior extent of
lession noted
 Best orientation for
demonstrating the
insertion of membranes
into the optic disc
Longitudinal Scan

23.  The probe is faced
centered on the
cornea
 Helpful for
documenting lesions
& membranes in
relation to the lens &
optic nerve and for
evaluating the
macular region
Axial Scan

24. Axial Scan
1.Horizontal axial(H)
 Eye in primary position &
Marker at nasal side.
2.Vertical axial scan(V)
 Eye in primary position &
marker at superiorly.
3.Oblique Axial scan (O)
 Eye in primary position &
marker at superiorly.

25.  Basic Screening Examination
 Transverse scans of the four major
quadrants at a high gain setting, from
limbus to fornix
 First superior portion  nasal portion 
inferior portion  temporal portion
 Special Examination Techniques
 Topograhic Echography
 Quantitative Echography
 Kinetic Echography
Examination Techniques For The Globe

26. Topographic Echography
 Shape
 Location- position, meridians
 Extension
 Contour abnormalities
Bone - excavation, defects, or hyperostosis
Globe - indentation or flattening

27. Topographic Echography
 Transverse – gross shape, dimension & lateral extent of
lesion
 Longitudinal – gross shape, dimension & antero
posterior extent between optic disc & ora of lesion
 Axial – lesion in relation to lens and optic nerve

28. Topographic Echography
A. Point-like
e.g. fresh V.H
B. Membrane-like
e.g. R.D
C. Mass-like
e.g. choroidal
melanoma

29. Quantitative Echography
Two Types - Type I & Type II
Type I – Histological architecture
 Depending on degree of variation of height(reflectivity) of
internal lesion spikes
 Homogenous
 Heterogeneous

30. Quantitative Echography
 Type II - used solely to differentiate a RD from a dense
vitreous membrane
 If membrane like lesion produce 100% tall spike at tissue
sensitivity in type l & other characteristic are equivocal
then type II applied
 Persistent movement of membrane reflectivity compared
with sclera of same eye

31. Kinetic Echography
Two types -
 Aftermovement – movement of lesion echoes following
cessation of eye movement eg non-solid, tumor
 Vascularity - Spontaneous motion of lesion echoes in
steadily fixating eye indicative of blood flow within
vessels

32. Evaluation Of The Macula:
 Four basic B-scan probe positions that allows
perpendicular sound beam exposure to the macula-
 Horizontal axial scan
 Vertical transverse scan
 Longitudinal scan
 Vertical macula scan

33. Anterior Segment Evaluation
Immersion Technique
 Can examine the cornea, anterior
chamber, iris, lens & retrolental
space
 Can measure axial eye length

34. Anterior Segment Evaluation
High-resolution technique (Ultrasound Biomicroscopy):
 Developed by Pavlin & colleagues
 uses sound wave of 50 to 100 MHz

35.  Three major portions:
 Orbital soft tissue assessment
 Extraocular muscle evaluation
 Retrobulbar optic nerve examination
 Two approaches:
 Transocular (through the globe)
 For lesions located within the posterior & mid-
aspects of the orbital cavity
 Paraocular (next to the globe)
 For lesions located within the lids or anterior orbit
Examination Techniques For The Orbit

36.  Positioning the patient
 Topical anaesthesia B/E
 Methylcellulose - a coupling medium
 Transocular Approach-
 Transverse scans
 Longitudinal scans
 Axial scans
Examination Techniques For The Orbit
 Paraocular Approach-
 Transverse scans
 Longitudinal scans
 Axial scans

38. Examination Techniques For The
Orbit
 Basic Screening Examination
 Mainly transocular approach
 Longitudinal scan - useful for lacrimal gland region
 Axial scan - useful for assessing the retrobulbar
space
 slight tilt to either side is more appropriate
 Axial length measurement

42. B-scan Indications
lid
 severe edema, partial or
total tarsorrhaphy
Cornea
 keratoprosthesis, corneal
opacities, scars, severe
edema
AC
 hyphema, hypopyon
Pupil
 miosis, pupillary
membrane
Lens
 cataract
vitreous
 hemorrhage,
inflammatory debris

44. B-scan indications contd..
Diagnostic B-scan
 Status of the lens, vitreous, retina, choroid, & sclera.
Diagnostic purposes even though pathology is clinically
visible.
 Differentiating iris or ciliary body lesions
 Ruling out ciliary body detachments
 Differentiating intraocular tumors
 Serous versus hemorrhagic choroidal detachments
 Rhegmatogenous versus exudative retinal detachments
 Disc drusen versus papilledema.
 IOFB

45. Doppler ultrasound
 It emits a beam of pulsed or continuous ultrasound that is
used to detect blood flow by means of the Doppler shift
(effect).
 Doppler effect is defined as a change in the frequency of
the sound wave that is caused by the movement of the
reflector
i.e. echo source.
 Reflector motion towards the transducer---- frequency of
returning echo greater and vice versa.

46. Doppler ultrasound
 Helpful in assessing the direction of flow within
orbital vessels and detection of blood flow within
orbital lesions.
 Incorporation of color doppler with the conventional
B scan imaging allows two dimensional presentation
of ocular and orbital images with simultaneous
doppler evaluation indicated by color changes in the
echogram.

47. Doppler ultrasound
 Red – blood flow toward probe whereas blue - away
 Use- study of vascular disorder of eye and orbit ,
blood flow characteristics of tumors.
47

48. Ultrasound bimicroscopy (UBM)
 Very high frequency ultrasound waves of 50 – 80
MHz
 Allows histological resolution of anterior segment
structures
 Use – defining abnormalities of the anterior chamber
angle, limbus and anterior part of retina.

49. Clinical Examples:

50. Vitreous

51. Vitreous Haemorrhage:

52. Vitreous degeneration

53. Posterior Vitreous Detachment
(PVD)
 Moderate to high reflective membrane
 Mostly disappears in low gains
 May or may not attach to ONH
 Good after movements

54. PVD
PVD

55. PVD attached to ONH

56. Retina

57. Retinal tear

58. Retinal Detachment (RD)
 High reflective membrane
 Always attached to ONH
 Membrane persists at low gain
 Very minimal or no after movements in kinetic scan

59. Retinal detachment

60. Retinal Detachment:

61. TRD
TRD

62. RD PVD
High reflective membrane Moderate to high reflective
membrane
Always attached to ONH May or may not attach to
ONH
Persists at low gain Mostly disappears at low
gain
Limited mobility and after
movements on kinetic scan
Good mobility and after
movements on kinetic scan
Uniform reflectivity of the
membrane all over
Reflectivity decreases at the
periphery of the membrane

63. Retinoschisis. (A) B-scan transverse view demonstrates a
smooth, thin, dome shaped membrane (arrowhead).
(B) On A-scan, a thin, 100% single-peaked spike can be
seen just anterior to the retina. R, retina; S , sclera;
V, vitreous.

64. Retinoblastoma
Criteria for diagnosis
1. Dome shaped appearance with a very irregular
configuration.
2. Internal reflectivity of the lesions vary according to
the degree of calcification within the lesions.
65

65. Retinoblastoma

66. Macular lesion
Macular lesion

67. Choroid

68. Kissing choroidals seen as a dome
shaped membrane not attached to the
optic disc.

69. Posterior Staphyloma

70. Choroidal melanoma
Specific criteria for diagnosis
1. Collar button ( i.e. mushroom) shape
2. Low to medium internal reflectivity
3. Regular internal structure
4. Internal blood flow (i.e. vascularity)

71. Choroidal Melanoma

72. Metastatic choroidal lession
from breast

73. Shadowing caused from sound
absorption by the calcium within a
choroidal osteoma

74. Choroidal hemangioma with an
associated exudative retinal
detachment

75. Sclera

76. Posterior Scleritis:

77. Nodular Scleritis with fluid in the Tenon
capsule. The scan on the right
demonstrates a positive T-sign at the
insertion of the optic nerve.

78. Scleral perforation
Scleral perforation

79. CB

80. Ciliary body detachment as seen
on high-resolution scan. Note the
large cleft in the subciliary space.

81. 360 degrees Ciliary detachment

82. Iris

83. High-resolution B-scan images of an iris melanoma. This
imaging requires a separate probe, and it delivers high
magnification and superior detail of the small structures of the
anterior segment. On the left is a longitudinal, or radial, scan,
and on the right is a transverse, or lateral, scan.

84. Lens

85. Dislocated Lens:

86. Optic Nerve

87. Optic disc drusen

88. Increased subarachnoid fluid
around the optic nerve. Note the
positive crescent sign.

89. Glaucoma

90. Optic disc cup. (A) Fundus photograph
showing large optic disc cup suggestive
of advanced glaucoma. (B) B-scan USG
demonstrates corresponding concave
bowing of the optic disc (arrows).

91. Closed angle. (A) Peripheral iridocorneal
touch observed with UBM indicates that the
angle is closed (arrow). (B) After peripheral
iridotomy (arrowhead), the angle (arrow) has
opened.

92. Plateau iris configuration. (A) The iris approach
toward the anterior chamber angle is flat, and the
angle is closed (white arrow). Note anteriorly
placed ciliary processes (black arrow). (B) Even
after the peripheral iridotomy (arrowhead), ciliary
processes prevent the peripheral iris from falling
away from the trabecular meshwork

93. Congenital anomalies

94. Persistent hyaloidal vessel

95. Coloboma
Coloboma

96. Coloboma with RD

97. Others

98. SB
Scleral buckle

99. Sponge

100. SO filled globe
Silicon oil filled globe

101. Gas filled globe
Gas filled globe

102. Artifacts

103. IOFB
IOFB

104. Retinopathy of prematurity
105

105. Thyroid ophthalmopathy
106

106. Thank you