2. Introduction
• Ultrasound biomicroscopy (UBM) provides high-
resolution imaging of the anterior segment in a
noninvasive fashion.
• In addition to the tissues easily seen using conventional
methods (ie, slit lamp), such as the cornea, iris, and
sclera, structures including the ciliary body and zonules,
hidden from clinical observation, can be imaged and
their morphology assessed.
• Pathophysiologic changes involving anterior segment
architecture can be evaluated qualitatively and
quantitatively.
3. INTRODUCTION
• Recent technique to visualize anterior segment
with the help of high frequency ultra sound
transducer.
• UBM (anterior segment ultrasonography) is
performed with a 50 Mhz probe.
• The resolution of 50 MHz probe is 40 microns
and the depth is 4 mm
4. • UBM is done with the patient in the supine
position and the eye is open.
• Since the piezoelectric crystal of the transducer
is open it should not come in direct contact with
the eye to prevent injury to the cornea
5.
6.
7.
8. • There is a special cup which fits in between the
eyelids, keeping them open
• The eye cup is filled with saline or sterile
methylcellulose.
• The crystal of the transducer is placed in saline
approximately 2 mm from the eye surface.
(This distance of 2 mm prevents injury to the
cornea and also helps as a fluid standoff.)
• The eye is scanned in each clock hour from the
center of the cornea to the ora serrata
15. Corneal dystrophy
Corneal dystrophies can be imaged and the depth of pathology
defined. Granular dystrophy shows highly reflective hyaline bodies in
the superficial stroma.
29. Iridociliary cyst
The most common clinical presentation of an irido-ciliary cyst
is a peripheral iris elevation - the typical UBM finding of a thin
walled structure with no internal reflectivity is diagnostic.
42. Angle recession
Angle recession is imaged as a tear into the face of the
ciliary body. Ciliary body tissue is still imaged attached to
the scleral spur.
46. • UBM is useful in opaque media
• The most important limitation of UBM is
depth. UBM cannot visualize structures
deeper more that 4 mm from the surface.
• The other limitation is that UBM cannot
be performed in presence of an open
corneal or scleral wound.
• It is time consuming
48. • Tomographic techniques generate slice
images of three-dimensional objects.
• Optical tomographic techniques are of
particular importance in the medical field,
because these techniques can provide non-
invasive diagnostic images
49. • Optical coherence tomography is a non-
contact, real-time technique that uses low
infrared laser energy to image structures.
50. • Optical coherence tomography imaging is based on
measuring the delay of light (typically infrared) reflected
from tissue structures.
• Because light travels extremely fast, it is not possible to
directly measure the delay at a micron resolution.
Therefore, OCT employs low-coherence interferometry
to compare the delay of tissue reflections against a
reference reflection.
51. • To obtain an OCT image, the instrument scans a light
beam laterally, creating a series of axial scans (A-scans),
after which it combines these A-scans into a composite
image.
• Each A-scan contains information on the strength of
reflected signal as a function of depth.
52. • The more commonly used retinal OCT
uses 820-nm light, which allows for
excellent tissue penetration to the level of
the retina.
• The anterior segment OCT utilizes 1310-
nm light, which has greater absorption
resulting in limited penetration.
53. • This allows for increased intensity of the
light as decreased amounts reach the
retina.
• The light is 20 times more intense, giving
a much greater signal-to-noise ratio.
• This increased intensity allows for
increasing the speed in imaging 20 times,
with decreased motion artifact.
54. • Compared with other imaging modalities,
OCT has a higher-depth resolution.
• Resolution is determined by the
wavelength and the spectral bandwidth of
the light source, Shorter wavelengths and
wider bandwidths provide better
resolution.
55. Types of oct system
There are two principles of image
acquisition and data processing in anterior
segment OCT:
• Time domain and
• Fourier domain algorithms.
56. • In time domain OCT, there is a mechanical moving
part that performs the A-scan, Thus, the rate of the
scan is limited by the movement of the part.
• In Fourier domain OCT, the information in an
entire A-scan is acquired by a charge-coupled
device (CCD) camera simultaneously. As there is
no mechanical movement, the scan time in Fourier
domain OCT is faster. This is an important
advancement because faster acquisition time
means lesser variability in the result due to the
patient’s eye movements.
57. Scans
• Anterior Segment Scan (16 x 6 mm)
• Single, Dual or Quad lines
• 256 A scans / .125 sec acquisition per line
• High Resolution Scan (10 x 3 mm)
• Single or Quad
• 512 A-scans / .25 sec acquisition per line
• Pachymetry Scan (10 x 3 mm)
• 8 radial lines
• 128 A scans / 0.5 sec total acquisition time
• All Scans adjustable in orientation and direction
68. PHAKIC IOL
PRE OP PLANNING POST OP OBSERVATION
ACD PCIOL DEPTH AND CENTRATION
ANGLE TO ANGLE IRIS POSITION
ANTERIOR CHAMBER ANGLE CRYSTALLINE LENS VAULT
IRIS OR CRYSTALLINE LENS ENDOTHELIAL SAFETY DISTANCE
POSITION
ACCOMADITVE ANALYSIS ACCOMADITIVE ANALYSIS
83. Advantages of AS OCT
• Technicians can do the scanning
• Imaging flexibility
• Faster imaging reduces error
• Image through an opaque cornea
• It's easy to image accommodative changes
• Scans can be taken immediately after
surgery
84. Limitations
• Pigmentation on the posterior side of the
iris blocks the penetration of infrared
light.
• Trabecular meshwork/ ciliary body not
seen
• Manual angle measurement
92. History
• History of present illness
• Associated history
• Past history
• Family history
93. History
• History of present illness :age of onset
• Associated history duration
• Past history one/both eye
• Family history variability
94. History
• History of present illness
• Associated history : diplopia
• Past history odynophagia
• Family history muscle weakness
cardiac problem
night blindness
95. History
• History of present illness
• Associated history
• Past history : trauma/ surgery
• Family history contact lens
lid edema
allergy
dry eyes
96. History
• History of present illness
• Associated history
• Past history
• Family history
97. evaluation of ptosis
• head posture,Eyebrow position, eyelid
masses, inflammation, proptosis
• pupillary size, reaction, heterochromia
• Best corrected Visual Acuity: In
infants, make sure infant can fix and
follow light with each eye
• Cycloplegic Refraction
104. Measurements
• Vertical fissure height
• Margin reflex distance
• LPS action
• Lid crease level
• Lid level on down gaze
105. Vertical fissure height
• The distance between the upper and lower
eyelid in vertical alignment with the center of
the pupil in primary gaze, with the patient’s
brow relaxed.
• Normal – 9-10mm in primary gaze
• Should be seen in up gaze, down gaze and
primary gaze
• Amount of ptosis = difference in palpebral
apertures in unilateral ptosis or Difference
from normal in bilateral ptosis
106.
107. Grading of severity of ptosis
< or = 2mm : mild ptosis
= 3 mm : moderate ptosis
= or > 4 mm : severe ptosis
108. MRD
• Margin-to-reflex distance 1 (MRD1) : is the
distance from the central pupillary light
reflex to the upper eyelid margin with the eye
in primary gaze.
• A measurement of 4 - 5 mm is considered
normal.
• If the margin is above the light reflex the
MRD 1 is a +ve value.
• If the lid margin is below the corneal reflex
in cases of very severe ptosis the MRD 1
would be a –ve value.
109.
110. MRD
• Margin-to-reflex distance 2 (MRD2) : is
the distance from the central pupillary
light reflex to the lower eyelid margin
with the eye in primary gaze. .
• The MRD1 plus the MRD2 should equal
the palpebral fissure measurement
111. Levetor function
• is the distance the eyelid travel from
downgaze to upgaze while the frontalis muscle
is held inactive at the brow.
• The normal levator function is between 13-
17mm
112. • Lid excursion is a measure of the levator
function. The frontalis action is blocked by
keeping the thumb tightly over the upper
brow and asking the patient to look up from
down gaze and measuring the amount of upper
lid excursion at the center of the lid.
114. Grading of levator action
< 4mm – poor levator function
5-7 mm – fair levator function
8-12 mm – good levtor function
115. Lid crease
• Position is the distance from the crease to lid
margin
• Normal – 8 to 10mm in primary gaze
• An absent lid crease is often accompanied by
poor levator function.
• If a lid crease is present but is higher than
normal and if a deeper upper lid sulcus is
found on that side, note these as signs of a
levator aponeurosis disinsertion.
116.
117. Phenyl ephrine test
• Patients with minimal ptosis (2 mm or less) should
have a phenylephrine test performed in the involved
eye or eyes
• Either 2.5 or 10% phenylephrine is instilled in the
affected eye or eyes. Usually two drops are placed
and the patient is reexamined 5 minutes later.
• The MRD1 is rechecked in the affected and
unaffected eyes .
• A rise in the MRDl of 1.5 mm or greater is
considered a positive test. This indicates that
Müller's muscle is viable
