Ultrasound is a useful tool for evaluating orbital diseases. It uses high frequency sound waves to create images of intraocular and orbital structures. A systematic ultrasound examination involves evaluating the orbital soft tissues, extraocular muscles, and retrobulbar optic nerve. Abnormalities are identified based on changes in location, size, shape, internal reflectivity, and mobility compared to the normal structures. This allows differentiation of various pathologies, such as cysts, masses, muscle thickening, and optic nerve swelling. A comprehensive ultrasound examination provides valuable information for diagnosing and monitoring orbital diseases.

1. ULTRASOUND METHODS FOR
EVALUATING ORBITAL DISEASES
(By Dr Zain Khatib)
MODERATOR:
Dr Y B Bhajantri

2. 1. BASICS OF ULTRASOUND
2. ORIENTATION AND
EXAMINATION TECHNIQUES
3. ORBIT EVALUATION

3. PHYSICS
 “ULTRASOUND WAVE” – By definition
Acoustic Wave (Sound wave) + Frequency > 20,000Hz (20KHz)
 Higher the frequency, lower is the wavelength of wave
 In clinical practice – 5 MHz to 50 MHz

4. High Frequency
Small wavelength
Less Penetration
+
Better Resolution

5. ABDOMINAL USG OPHTHALMIC USG
Low
frequency
(1 to 5 MHz)
Longer
wavelength
Lower
Resolution
(abdominal
and pelvic
structure)
High
frequency
(8 to 10
MHz)
Short
wavelength
Higher
Resolution of
minute ocular
and orbital
structure

6. ECHO
 When Ultrasound waves passes through a medium, on
striking a surface a part of it is reflected back and this is
called Echo.
 Ultrasound interpretations are based on Echoes.
 Produced at the junction of media with different Acoustic
Impedance.
 Acoustic impedance = Sound velocity x Density.
 Greater the difference in Acoustic Impedance of the 2 media,
stronger the reflection of ultrasound wave i.e. Echo.

9. Factors affecting echoes :
1. Angle of sound incidence.
2. Nature of acoustic interfaces.
3. Absorption.
4. Refraction.

10. ANGLE OF INCIDENT BEAM

11. NATURE OF ACOUSTIC
INTERFACES

12. ABSORPTION
Results in heat production.
Higher frequency absorbed to greater
extent.
More the thickness of medium more is the
absorption .

13. REFRACTION

14. ULTRASOUND SYSTEM
PULSE- ECHO SYSTEM
Requires Production of
multiple short pulses of
Ultrasound energy with
brief intervals between
pulses;
Interval allows returning
echoes to be detected,
processed & displayed.

15. • Electrical
energy
• Mechanical
vibration
• Ultrasound
wave

16. AXIAL RESOLUTION
 Damping Material - consists
of metal powder mixed with
plastic or epoxy.
 Serves to limit vibrations of
the crystal that produce the
pulses of ultrasound energy,
thus shortening the pulse

17. LATERAL RESOLUTION
• PLANAR CRYSTAL
LENS
• ADDITION OF AN
ACOUSTIC LENS

18. SIGNAL PROCESSING
 Electric signal produced by the returning echoes is initially
received by the ultrasound instrument as a very weak
radiofrequency signal.
 The type of amplification used affects the ability of ultrasound
system to display differences in strengths of various echo
signals.
 3 types of amplifications :
1. Linear
2. S- shape
3. Logarithmic

19.  Linear :Limited range of
echo intensities.
Sensitive to small
variation.
 Logarithmic : Wide range
of echo intensities.
Not sensitive to small
variation.
 S- shaped : Wide range
and great sensitivity.

20. GAIN
 Gain is measured in decibels
(db), which represents
relative units of ultrasound
intensity.
 The higher the gain level, the
greater the ability of the
instrument to display weaker
echoes.
eg. Vitreous opacities .
 As the gain is lowered, only
the stronger echoes will
continue to be displayed.
eg. Retina and Sclera.

21. INSTRUMENTATION
 A scan echography: One dimensional acoustic display in
which echoes are displayed as a vertical spike from the
baseline (A – Amplitude)

22.  B scan echography: 2 dimensional acoustic display (sound
beam slices through the tissue)
 Echo is represented as a dot on the screen rather than a
spike, strength of echo indicated by brightness of dot
(B – Brightness)

23. STANDARDIZED ECHOGRAPHY
The combined use of
A scan and B scan
 B scan – Topographic
nature of intraocular &
orbital structures and
lesions.
A scan – Lesions
character and size

24. ORIENTATION & EXAMINATION
TECHNIQUES
 Pt. Position : Most examination are performed with Pt.
Reclined.
 Occasionally helpful to examine pt. in sitting position.
e. g. Posterior Hyphema, Orbital hematoma
 Patient head and the instrument should be kept close
together, so that probe position and the screen can be
viewed simulataneously by the examiner.

25.  All the probes contain a transducer that
oscillates rapidly back and forth near the
face (ie tip) of the probe.
 Each probe has a marker i.e. dot, line and
logo that indicate the sides of the probe that
is represented on the upper position of the
B scan screen display.
 Upper part of the echogram corresponds to
the position of the globe where the probe
marker is directed.
 Centre of scan corresponds to central
position of probe face and because the best
resolution of echogram is in the central
region- area of interest should be centered
within the echogram whenever possible.

26.  Probe: Can be placed directly over the conjunctiva, cornea
or placed over the lids.
Former Advantage:
Reducing sound attenuation caused by lid.
Also with lids closed the portion of the globe being evaluated
is uncertain.
Disadvantage:
Requires sterilization of probe between procedures.
 Coupling solution- methylcellulose- to avoid attenuation
caused by air.

27. B SCAN PROBE ORIENTATION
TECHNIQUES
 BASIC PROBE ORIENTATION:
1. TRANSVERSE SCANS
2. LONGITUDINAL SCANS
3. AXIAL SCANS
 ORBITAL EXAMINATION:
1. TRANSOCULAR 2. PARAOCULAR
- TRANSVERSE - TRANSVERSE
- LONGITUDINAL - LONGITUDINAL
- AXIAL

28. SPECIALIZED ORBITAL
EXAMINATION:
TRANSOCULAR:
 Examination through the globe
 Useful for lesions in posterior and mid orbital cavity
PARAOCULAR:
 Examination next to the globe
 Useful for lesions within the eyelids or anterior orbit

30. TRANSOCULAR TRANSVERSE
SCAN
 Longest diameter of probe is placed parallel (tangential) to
limbus outside the cornea
 Back and forth movement of transducer is parallel to the
limbus
 A circumferential slice is produced on opposite side
 This helps in determining lateral extent of a lesion
 Patient is asked to look to the side that needs to be
examined and away from the probe

32. By placing the probe at 6 o’ clock
position, the 12 o’ clock fundus is in
the centre of echogram, hence this is
called transverse scan of 12 o’clock
meridian

33. PROBE POSITION DIRECTION OF MARKER
TRANSVERSE SCAN TYPE:
HORIZONTAL
VERTICAL
OBLIQUE
NASAL
SUPERIOR
SUPERIOR

34. TRANSOCULAR LONGITUDINAL
SCAN
 The longest diameter of the probe is perpendicular to the
limbus, outside the cornea.
 The sound beam sweeps along the meridian opposite the
probe and thus this method provides anteroposterior
extent of the lesion.
 Peripheral (anterior) part is displayed superiorly and central
(posterior) part is displayed inferiorly.
 Patient is asked to look to the side that needs to be
examined and away from the probe.

36. The 6 o’clock probe placement examines
12 o’clock meridian and this is called
longitudinal scan of 12 o’clock meridian

37. PROBE ORIENTATION: TIP IS ALWAYS FACING
THE CORNEA

38. AXIAL SCAN
 Probe is centred on the cornea, the sound is directed through the
centre of the lens and optic nerve
 Easiest because lens and optic nerve is in the centre of
echogram, hence better orientation but sound attenuation and
refraction by lens will hinder the resolution

40. PROBE POSITION DIRECTION OF MARKER
TYPE OF AXIAL SCAN
HORIZONTAL
VERTICAL
OBLIQUE
NASAL
SUPERIOR
SUPERIOR

41. PARAOCULAR TRANSVERSE

42. PARAOCULAR LONGITUDINAL

43. ULTRASOUND EVALUATION OF
ORBIT
Orbital evaluation is divided into 3 major
components:
1. Orbital soft tissue evaluation
2. Extraocular muscle evaluation
3. Retrobulbar optic nerve evaluation
A systematic approach using both standardized
AScan & Bscan should be employed to detect
orbital lesions quickly and reliably.

44. ORBITAL SOFT TISSUE
EVALUATION
 The marked HETEROGENEITY of orbital soft tissue,
comprised of fat, connective tissue septae, blood vessels,
and nerves results in echograms that are very
HIGH REFLECTIVE ON A-SCAN and ECHODENSE ON B-
SCAN

45.  Since most orbital lesions have a more
homogenous compositions than the normal
orbital soft tissue, they usually produce easily
recognizable defects in the echogram

46. ORBITAL
SCREENING
Best
assessment
is by
transocular
transverse
scans of the
4 major
meridians

47. Axial scan
done in the
end to
observe
retrobulbar
space and
retrobulbar
optic nerve

48. DIFFERENTIATION OF ORBITAL
LESIONS
1. TOPOGRAPHIC ECHOGRAPHY
• Location
• Shape
• Borders
• Contour abnormalities
- Bone: Excavation, Defects, Hyperostosis
- Globe: Indentation, Flattening
2. QUANTITATIVE ECHOGRAPHY
• Internal Reflectivity: Spike height
• Internal Structure: Histologic architecture
• Sound Attenuation: Absorption or Shadowing
3. KINETIC ECHOGRAPHY
• Consistency: Soft vs Hard
• Vascularity: Blood flow
• Mobility: Of lesions or its contents

49.  TOPOGRAPHIC ECHOGRAPHY
 Location
 Shape
 Borders
 Contour abnormalities
- Bone: Excavation, Defects, Hyperostosis
- Globe: Indentation, Flattening

50. TOPOGRAPHIC ECHOGRAPHY
 LOCATION, SIZE, SHAPE:
1. Transverse Scan

51. Contd…..
2. Longitudinal Scan

53.  Paraocular approach for masses confined to anterior orbit

54.  BORDERS:
Well outlined: cysts, masses covered with capsule,
pseudocapsule
- Smooth regular contour and rounded shape on B scan
- High reflectivity spike on A scan
Poorly outlined: Indistinct, diffuse, eg. pseudotumour
- Indistinct, irregular contour on B scan
- Low reflectivity spike on A scan

55. INCLUSION CYST PSEUDOTUMOUR
WELL ENCAPSULATED
BENIGN LACRIMAL
GLAND TUMOUR

56.  Contour changes in globe and bone

57.  2. QUANTITATIVE ECHOGRAPHY
 Internal Reflectivity: Spike height
 Internal Structure: Histologic architecture
 Sound Attenuation: Absorption or Shadowing

58. QUANTITATIVE ECHOGRAPHY
INTERNAL REFLECTIVITY:
 Means evaluating the strength of a lesions internal echoes.
 A scan: height of the spikes
 B scan: brightness of the internal dots
INTERNAL STRUCTURE:
 Refers to the degree of variation in histologic architecture
within a lesion
 Evaluated by noting the differences in height of A scan spikes
and difference in echodensity on B scan

59. 1. Normal Orbit: Heterogeneous tissue – high
reflectivity
2. Cavernous Hemangioma: Multiple large blood
filled spaces – moderately high reflectivity
3. Benign mixed tumour of lacrimal gland: Multple
cystic cavities filled with mucinous material –
medium reflectivity
4. Hemangiopericytoma: Mildly heterogeneous
histologic architecture – low to medium reflectivity
5. Lymphoma: Homogenous densely cellular lesion
– low reflectivity

60. LYMPHOMA LYMPHANGIOMA

61. SOUND ATTENUATION: ORBITAL SHADOWING
 Highly reflective media obstruct the pathway of Ultrasound wave
eg. Calcium, bone, foreign material (or lesion being highly reflective itself)
CAVERNOUS HEMANGIOMAS

62.  3. KINETIC ECHOGRAPHY
 Consistency: Soft vs Hard
 Vascularity: Blood flow
 Mobility: Of lesions or its contents

63. KINETIC ECHOGRAPHY
 CONSISTENCY: Assessed by Compressibility testing

64. VASCULARITY:
 Indicates presence of
blood within a lesion
 Internal lesion A scan
reflectivity spikes are
observed in real time for
a fast, spontaneous,
flickering motion

65. MOBILITY: Of orbital lesions or its
contents
 If a lesion is mobile, it moves on
ocular mobility
(ask patient to perform a saccade
or rapidly blink)
 Movement within a lesion: shifting
of fluid level on changing body
position, eg. Blood in a hematoma

67. EVALUATION OF EXTRA
OCULAR MUSCLES
 EOM thickening is the commonest abnormality encountered
in orbital echography
 USG is the most sensitive imaging for detecting early and
subtle muscle thickening
 EOMs are surrounded by sheaths that produce distinct,
highly reflective interfaces
 EOM fibers are relatively compact and homogenous, thus
medium reflective on A scan, and less echodense than
surrounding orbital tissue on B scan

69. EXAMINATION OF RECTI MUSCLES
Transverse and longitudinal scans are
carried out of the 12, 3, 6, and 9 o clock
positions to examine the superior, medial,
inferior and lateral rectus muscles
respectively
Patient is asked to look towards the muscle
being examined
(10 degrees)

70. TRANSVERSE SCANS

71. LONGITUDINAL
SCAN

72.  Contralateral muscles should always be checked for
comparison of thickness and size, with the patient fixating
both eyes similarly

75. EXAMINATION OF OBLIQUE MUSCLES
SO: Orbital apex –
superomedial wall of orbit –
trochea – insertion into
superior sclera
IO: Medial floor of orbit –
passes below IR- inserts into
globe just inferior to macula

76. SUPERIOR OBLIQUE
OBLIQUE TRANSVERSE &
LONGITUDINAL – 2 o clock

77. INFERIOR OBLIQUE
OBLIQUE TRANSVERSE &
LONGITUDINAL – 7 o clock

78. THYROID ORBITOPATHY – MEDIAL RECTUS THICKENING

79. MYOSITIS: MEDIAL RECTUS THICKENING WITH TENDON INVOLVEMENT

80. TO vs MYOSITIS

81. RETROBULBAR OPTIC NERVE
EVALUATION
 The intraorbital portion of
optic nerve is a distinct
homogeneous tubular
structure that courses
through the orbit in a
sinuous fashion
 Axial scan – not of much
value, only helps in
documenting marked
changes in optic nerve
thickness

82. TRANSVERSE SCAN:
• Patient looks slightly nasally,
and a vertical transverse scan
from the temporal side produces
a vertical cross section of the
nerve

84. RETROBULBAR NEURITIS vs ISAF (PSEUDOTUMOUR CEREBRI)

85. THE 30 DEGREE TEST
 A Scan technique
to diff between
ISAF and nerve
parenchyma
thickening
 Based on the
assumption that
when the eye is
turned, nerve is
stretched, thus
distributing the
ISAF over greater
area

86. OPTIC NERVE SHEATH TUMOUR
(GLIOMA)
• Mass that replaces the normal
optic nerve void on B scan
• A scan shows low to medium
reflective spikes

87. THANK YOU
REFERENCES:
1. ULTRASOUND OF EYE AND ORBIT: Sandra Frazier
Byrne, Roland L. Green
2. DYNAMIC OPHTHALMIC ULTRASONOGRAPHY: Julian
Pancho S. Garcia, Jr., MD