This presentation is mainly focused on the clinical diagnosis and interpretation of oct macula.This is presented on 4th year optometry as topic presentation.

1. OPTICAL COHERENCE
TOMOGRAPHY
ANUJA DHAKAL ADHIKARI
B.OPTOMETRY , FINAL YEAR

2. LAYOUT
• INTRODUCTION
• HISTORY OF OCT
• TECHNICAL DESCRIPTION OF OCT
• PRINCIPLE OF OCT
• TYPES OF OCT
• MACULA OCT
• INTERPRETATIONS
• ADVANTAGES AND DISADVANTAGES
• ADVANCES IN OCT
• FURTHER RESEARCH ON OCT

3. INTRODUCTION OF OCT
• Optical coherence tomography (OCT) is a diagnostic, non-invasive, non-contact,
transpupillary imaging system which provides high resolution cross-sectional
images of anterior eye, the retina, vitreous and optic nerve.
• In vivo “optical biopsy” of the retina.
• Fast scanning rates and quick signal processing allows for image visualization in
real time and at a video rate.
• OCT is also useful in other medical specialties, including otolaryngology,
cardiology, gastroenterology, and vascular surgery.

4. HISTORY
• The use of OCT in posterior segment imaging was first reported by Huang et al in
1991.
• Since it became readily available for clinical use in the mid-1990s, OCT has
revolutionized the way ophthalmologists diagnose and manage certain eye
conditions.
• The OCT breakthrough was the capability to obtain high resolution histological
images in vivo, in real time in non-invasive way and using harmless radiation (low
power near infrared radiation, usually).

5. 1971
1996
1991
1993 2000
2002
2006
2012
2014
Concept of
“seeing inside
tissue”
First OCT
image of
in-vitro
retina
First OCT
image in-
vivo retina
First
commercial
ophthalmic
OCT
2nd gen of
ophthalmic
OCT
3rd gen of
stratus
OCT
Commercial
SD-OCT
Commercial
Swept source
OCT
Commercial OCT-
Angiography

6. TECHNICAL DESCRIPTION
• First and second generation OCT produces cross sectional images of the retina
with an axial (depth) resolution of approx 12 – 15 micro meter, current
commercial OCT offers a resolution of 8 – 10 micrometer – 10 x better than
Ultrasound.
• Third generation OCT (OCT3) uses 500 axial scans taken in 1 second and has
increased the resolution to 7 – 8 micrometer.
• Due to the interferometric measurements method,the axial resolution is defined by
the light source , not the focusing optics.

7. • The OCT two-dimensional scans are processed by a computer, then corrects for
axial eye movement artifacts. The scans are then displayed in a false color
representation scale in which warm colors (red to white) represent areas of high
optical reflectivity and cool colors (blue to black) represent areas of minimal or no
optical reflectivity.

9. PRINCIPLE OF OCT
• low coherence interferometry.
• The OCT setup is generally mounted with a Michelson interferometer, and can be
divided in the following main parts:
light source ( superluminescent diode)
Scanning system
Light detector .
These items define almost all crucial properties of the system.

13. • OCT technique is based on Michelson interferometer to produce tomographic
images. A light source, expressed in terms of it’s electrical field amplitude is
introduced in the Michelson interferometer and is directed to the beamspliter.
• An interferometer splits light coming from a source into two separate paths and
combines the light coming back from the two paths at the interferometer output.
• Constructive interference
• Destructive interference

14. LIGHT SOURCE
• Uses broad-band light source .
• Four main desired characteristics:
Wavelength
Spectral bandwidth
Intensity and stability.
• To biological tissue studies, the region known as “diagnostic window” is often used. This
spectral region is between 800 nm and 1300 nm.
• Super Luminescent LED (SLED) : High intensities,High spectral stability &
spectral band of 30 nm.

15. • Lasers : Applied in OCT research, most of them using a Ti:Sapphire laser &
femtosecond laser which produces a broadband radiation.
Lasers are a most flexible, about spectrum and intensity.
 In this type of fibers, nonlinear effects produces spectra large as 400 nm,allowing
submicron of spatial resolutions.
• Swept source : Broadband laser with an intracavity optical narrowband filter.

16. SCANNING SYSTEM
1)TIME DOMAIN OCT
• Time domain oct uses a broadband light source (infrared light source of 810nm)
and the reference arm contains a moving mirror that allows scanning of each depth
position in the image pixel by pixel.
• 3rd generation stratus oct is mainly used and it can’t picture 3D images.
• Pathlength of the reference arm is translated longitudinally into time.

17. 2)FREQUENCY DOMAIN
• light source of 840 nm.
• The main advantage of Frequency Domain OCT it is that, once that a CCD based
spectrometer is used, there is no need of any mechanical variation in time.
• The principle optical setup of FD OCT is similar to time domain oct,but the point
detector is replaced by a spectrometer.
• All the depth information, the scattering profile, is encoded in the spectral
interference pattern.

18. 3) SWEPT SOURCE
• light source of 1040 nm.
• Due to the source features the spectrum is acquired as a function of time& there is
a relationship between time and wavelength.
• SS-OCT a single photo-detector is used (no gratings, no moving mirrors and
CCDs). Mechanically the SS setup has no moving parts.
• 10 to 50 x quiker than traditional OCT and, due to SS be a laser, the SS intensity is
greater than superluminescent LED, allows deeper tissue penetration.

19. OCT DEPTH RESOLUTION
• OCT depth resolution is determined by the wavelength band of the light source,and is
unrelated to OCT detection technologies.
• Namely, OCT depth resolution (∆Z) can be shown with the following mathematical
formula:
∆Z = 0.44 × λ2/∆λ
(where λ is centre wavelength and ∆λ is wavelength range)

21. SPECKLE NOISE
• Speckle noise occurs when an object is scanned with coherent light,
and is the most common cause of blurring to retinal layer boundaries
on OCT B-scan images.
• Removal of speckle noise by multiple B-scan averaging.

22. A=1 BSCAN
B=10 BSCANS
C=100 BSCANS

23. DIFFERENCES
FEATURES TD OCT FD OCT
SPEED SLOWER THAN EYE MOVEMENTS FASTER THAN EYE MOVEMENTS
REFERENCE MIRROR MOVING STATIONARY
A-SCANS
DIMENSION OF
IMAGE
GENERATED SEQUENTIALLY
2D IMAGES
ENTIRE A-SCANS AT ONCE WITH SPECTROMETER
ANALYSIS
3D IMAGES
FRAME RATE
RESOLUTION
20
10 MICRON DEPTH RESOLUTION
UPTO 100
5 MICRON DEPTH RESOLUTION
LINES PER FRAME 240 450-500
AXIAL RESOLUTION
A-SCANS PER
SECOND
10-20
400 SCANS
10-20
26,000 SCANS
SCAN DIAMETER 7MM 8.3-10 MM

24. OCT IN OUR SETUP
HEIDELBERG ENGINEERING SPECTRALIS OCT
photo posted with patient’s and examiner’s consent

25. SPECTRALIS OCT
• Introduced in 2006 based on the Heidelberg Retina Angiogram 2 (HRA2).
• It incorporated two imaging techniques :
confocal scanning laser ophthalmoscopy
optical coherence tomography.

26. Confocal scanning laser ophthalmoscopy(CSLO)
Offers a variety of laser sources providing different illumination wavelengths and
detection schemes.
CSLO imaging in the near infrared (IR) in the green and blue wavelength range,as
well as fluorescence imaging modes of Angiography and for Autofluorescence.
Optical coherence tomography
Confocal imaging creates a transversal image of the retina corresponding to the
en-face plane of oct.
Uses or utilizes the IR CSLO scans for Automatic motion tracking.

27. FEATURES OF SPECTRALIS OCT
• Uses Broad-band superluminescent Diode & Spectrometer.
• SLO has a center wavelength of 880 nm & spectral bandwidth of 40 nm resulting
in an axial resolution of approximately 7 micronmeters in the eye.
• Optical oputput = 1.2 mw.
• OCT frame rate is determined by scan density & camera’s read out time.
• Algorithm to combine multiple images= ART MEAN(Automatic real time Mean).

29. OCT SCANS PROTOCALS:
1. MACULAR THICKNESS SCAN
2. RETINAL NERVE FIBRE LAYER SCAN (RNFL SCAN)
3. OPTIC NERVE HEAD SCAN
4. AS-OCT
5. ANGIO-OCT
6. EDI OCT

30. 1) MACULAR THICKNESS SCAN

32. 1) LINE SCANNING OPHTHALMOSCOPE
• Thickness profile (tomogram).
• The image overlaid & colour coded over the fundus image.
= slice navigators
In dense scan only 49 line images are taken.
ART= automatic real time scan
HS=high speed scans

33. 2) ETDRS GRID
• Measures the thickness from internal limiting membrane to RPE.
• Consists of 3 circles outer ,inner and innermost circles.

34. 3)CROSS HAIR-LINE IMAGE OF THE MACULA
• Black and white or colour coded images.
• Image represent the cross hairline images of the macula taken in the horizontal
direction,temporal to nasal.

35. 4) LINE RASTER SCANS
• Selective scanning profile .
• Usually taken at angle of 30 degrees.

37. WHICH EYE IS THIS ?
Picture of Right eye as we can see the thick RNFL hyperreflective band exiting the retinal
through optic nerve head

38. INDICATIONS FOR MACULAR OCT
• Detection of fluid within the retinal layers or under the retina (which may not be
visible clinically),
• Macular holes, pseudoholes,
• Epiretinal membranes (ERMs),
• Vitreo-macular adhesion (VMA),
• Vitreo-macular traction (VMT),
• Exudates
• Retinoschisis,
• Retinal detachment,
• Detachments of the retinal pigment epithelium
• Diabetic retinopathy (DR),
• Age-related macular degeneration

39. MACULAR OCT CAN BE ANALYZED IN 5
DIFFERENT LAYERS AS:
1)PRE-RETINA
2)VITREORETINAL/VITREOMACULAR INTERFACE.
3)EPI-RETINA
4)RETINA
5)CHOROID

40. International Nomenclature for OCT
Suggested the terms band, layer, and zone for the layers of the retina
The term band refers to the three-dimensional structure of the retinal layers
anatomically.
The term zone describes those regions on OCT whose anatomical correlation is
not clearly delineated.
The RPE/Bruch’s complex is one of the layers described as zone as they are
inseparable owing to interdigitation of cellular structure or tissue.

41. 1)PRE-RETINA
• Comprised of vitreous anterior to the retina.
• Non reflective dark spot in the oct.
• Faint-dots indicate noise formed due to electronic aberrations.

42. 2)VITREORETINAL/VITREOMACULAR INTERFACE.
• Well defined due to the contrast between the non-reflective vitreous and the
backscattering retina.
• The condensed vitreous overlying the ILM is called posterior vitreous face and
are bound at their interface. fibronectin,laminin and other extracellular
components that form a glue like matrix.

43. 3)EPI-RETINA
• Anterior surface of the retina.
• An epiretinal membrane (ERM) is a fibrocellular tissue,semi-translucent and
proliferates on the surface of the ILM. Retinal glial and retinal pigment epithelial
cells are the major components of ERM.Idiopathic ERMs is the most common
presentation.

44. 4)RETINA
• Anterior boundary formed by hyperreflective band of ILM and bounded
posteriorly by RPE.
• Different intermediate layers of the neurosensory retina can be seen with different
characteristic reflectivity patterns.

45. OUTER RETINA
(INTERNATIONAL NOMENCLATURE FOR OPTICAL COHERENCE TOMOGRAPHY PANEL)
1)ELLIPSOID ZONE:
Hyper reflective band ,formed mainly by the mitochondria within the outer portion of the
inner segments of photoreceptors.Previously referred as IS/OS junction.
2)MYOID ZONE :
Hyporeflective region between EZ to ELM.Hporeflectivity is attributed to the low packing
density of the mitchondia in the myoids.
3)INTER-DIGITATION ZONE:
Previously referred as COST or ROST. corresponds to the apices of the RPE cells that
encase part of the cone outer segments .
4)RPE-BRUCH’S COMPLEX:
2 Hyper reflective bands separated by hyporeflective layer,often not separatable on
normal conditions.

46. 5)CHOROID
• SS-OCT and EDI-OCT have enabled us to image choroid.
• which is seen as the multiple layers going from the innermost BM to the
choriocapillaris, sattler layer, haller layer and a hyperreflective line indicating the
choroido-scleral junction.
To be discussed later on another presentation on OCT.

47. WHAT’S FOVEAL CUT?

48. Foveal cut is the area where the outer plexifom and retinal nerve fiber layer meet.

49. INTERPRETATIONS OF OCT
QUALITATIVE
ANALYSIS
1)MORPHOLOGICAL
STUDIES
2)REFLECTIVITY
STUDIES
QUANTITATIVE
ANALYSIS
1)RETINAL
THICKNESS
2)RETINAL MAPS

50. QUALITATIVE ANALYSIS
1) MORPHOLOGICAL STUDIES
• Overall retinal changes,retinal outline.
• Vitreoretinal interface to choroid in new generation of oct.
• Major regions : Pre retinal area.
Epi-retinal area.
Intra-retinal area.
Sub retinal area.

51. 2) REFLECTIVITY STUDIES
• Hyperreflectivity :Appear as White and is reflecting light.
• Hyporeflectivity : Appears as dark and caused due to absorption of light.
• Shadowing: Due to increased light absorption.
• Reverse shadowing: Due to loss of pigmented tisuue causing excessive light to be
transmitted to outer layers.

54. NORMAL REFLECTIVITY OF STRUCTURES.
HIGH
REFLECTIVITY
• Retinal nerve fiber layer
• Is/os junction
• Inter-digitation zone.
• Outer limiting membrane.
• RPE/BM complex.
• Ellipsoid zone .
MEDIUM
REFLECTIVITY
• Outer plexiform layer.
• Inner plexiform layer.
LOW
REFLECTIVITY
• Ganglion cell layer.
• Outer and inner nuclear
layers.
• Choriocapillaries.
• Photoreceptors layer.
• Myoid zone.
• Choroid.
• Henle’s nerve fiber layer.

55. ABNORMAL PATHOLOGICAL REFLECTIVITY.
1) HIGH REFLECTIVITY
SUPERFICIAL INNER REGION OUTER RETINA RPE-CHOROID
• Pre retinal
membranes .
• Epi-retinal
membranes.
• Cotton wool spots .
• Fibrosis.
• Haemorrhages.
• Haemorrhages. • Hard exudates.
• Intraretinal
haemorrhages.
• Calcification.
• CNVM.
• Hyperplasia.
• RPE atrophy.
• Naevus.
• Scarring.
• Fibrosis.

56. ABNORMAL PATHOLOGICAL REFLECTIVITY
CONTD.
2) MEDIUM REFLECTIVITY. 3) LOW REFLECTIVITY
• Lipofuschin
• Deposits.
• Fluid(retinal edema , SRF, sub-RPE)
• Cavities, Cysts.
• Detachments.
• Projected shadows.

57. ABNORMAL PATHOLOGICAL REFLECTIVITY
CONTD.
3)SHADOWING
SUPERFICIAL INTRARETINAL DEEP
a)Dense :
• Micro and Macroaneurysms
b)Imperfect
• Haemorrhages
• Cotton wool spots.
a)Dense :
• Haemorrhages
• Sub-retinal deposits
• Neovascularization
• Scars
b)Imperfect
• Laser spots
• Haemorrhages
• RPE atrophy.
• Naevus.
• Sub- epithelial parasitic cysts.

58. QUANTITATIVE ANALYSIS
1)RETINAL THICKNESS
• Retinal thickness is a reproducible and common quantitative measurement.
• The scan protocols, namely, 3D cube scan and radial scan generates the early
treatment diabetic retinopathy study grid with the thickness values displayed in
each sector.
• Displacement may depict thickness.
• Retinal thickness can be measured manually using the inbuilt caliper function.

60. Retinal thickness Values in microns, RPE-ILM.
Retinal thickening Calculated value to the thickness minus the population mean for
the variable under consideration.
Center point(CP) The intersection of the 6 radial scans of the fast macular thickness
protocol of the oct.
CPT( center point thickness) Average of the thickness values for the 6 radial scans at their point
of intersection.
Center subfield(CS) Circular area of diameter 1 mm centered around the CP;128
thickness are made in this circular area in fast macula protocol.
CSMT(central subfield mean thickness) Mean value of the 128 thickness value obtained in the CS.
Absolute change in thickness Difference in the thickness between 2 measurements made at
different time.
Relative change in thickness Absolute change in thickness divided by the baseline thickness.
Relative change in thicknening Absolute change in thickness (or thicknening) divided by the
baseline thickening.
Definitions of commonly used landmarks and measurements on OCT

61. 2)RETINAL MAPS
• colour maps
• numerical value in map sector.
A: Retinal nerve fiber layer, B: ganglion cell layer, C: inner plexiform layer, D: inner nuclear layer, E: outer plexiform
layer + outer nuclear layer, F: photoreceptor inner segment, G: photoreceptor outer segment.
Each retinal layer has high symmetry, but the ganglion cell layer and inner nuclear layer are slightly thinner temporally

62. WHAT TO LOOK FOR?
1)DETERMINE SCAN QUALITY
2)RATE OVERALL SCAN PROFILE
3)EVALUATE FOVEALPROFILE
4)IDENTIFY FOVEAL CUT
5)CARRY OUT STRUCTURAL ASSESMENT
-OBSERVE ALTERATION OF LAYERS
-IDENTIFYADDITIONAL STRUCTURES
PRE RETINAL
EPI-RETINAL
INTRA RETINAL
SUB RETINAL
SUB-RPE

63. Ten steps toward interpretation of an optical coherence tomography image
1)Determine the indication for the oct from the patient’s record,fundus pictures,angiograms,etc.Does the
OCT image shown the area of interest?
2)Is the scan protocol used appropriate for the information required?
3)Is the scan quality good enough for analysis?Identity artifacts,other findings that could affect image
quality
4)Use the macular Cube, 3D or volume scans for evaluation of the pathology,including the segment
maps.colour or grayscale images are both adequate.
5)Look at the macular thickness map and ETDRS grid and get an idea as to the location of the
pathology.Ensure that the overlay of the thickness map is centered on the fovea in the colour.SLO or IR
image.
6)Evaluate each layer from the posterior vitreous to the chorio-scleral junction if visible,for deviation from
the normal.The HD 5 line raster scans or line scans are preferable for this as they scan a precise location and
gave a higher resolution. Grayscale images are preferable.
7)Classically the abnormality into one or more of the following:change in contour, change in thickness
,change in reflectivity, loss of tissue.look for thr location of the abnormality. Layers involved either primarily
or as part of secondary effects.
8)Take measurements as appropriate in addition to the standard thickness measurements that are inbuilt in
the protocals.In case of follow-up scans,use software to analyze change.
9)Advanced analysis such as en face OCT images can be generated in selected instances.
10)Look for the presence of known biomarkers before making the final diagnosis.

64. TERMINOLOGIES FOR ALTERATION OF STRUCTURES
1)Irregularity
2)Fragmentation
3)Rupture
4)Interruption
5)Depression
6)Elevation
7)Thinning
8)Thickening

65. CLINICAL CASES
A)VITREOUS AND VITREO-MACULAR
INTERFACE PATHOLOGIES

66. 1)VITREOUS HAEMORRHAGE

67. • PRE-RETINAL SUB-HYALOID HAEMORRHAGE.IN THICK DENSE
HAEMORRHAGES YOU CANNOT VISUALIZE THE RETINA
POSTERIORLY .
• SHADOWING IS PRODUCED.INNER LAYERS CAN BE SEEN
HYPERREFLECTIVE AND AS YOU GO MORE DEEPER THE
RELECTIVITY DECREASES. PARTIAL VITREOUS DETACHMMENT CAN
BE SEEN OVER THE MACULA.

68. 2)ASTEROID HYALOSIS

69. • MULTIPLE HYPER REFLECTIVE SPOTS SEEN IN THE VITREOUS
CAVITY.
• MOST OF THEM ARE PRESENTED IN CASES OF DIABETIC
RETINOPATHY SO ALWAYS LOOK FOR VITREOUS MEMBRANES OR
PULL ON THE RETINA.

70. 3)VITREOUS CELLS

71. • FINER DETAILS WHICH COMPRISES OF FINE DOT LIKE
HYPERREFLECTIVE STRUCTURES MULTIPLE AND DIFFUSE IN
FASHION.
• MAINLY DUE TO INFLAMMATION.

72. 4)POSTERIOR VITREOUS DETACHMENT
1
3
2
4

73. 1)SUBTLE CHANGE ,THIN MEMBRANE WHICH IS PARTIALLY DETACHED
FROM THE RETINA.
2)CYSTOID MACULAR EDEMA SECONDARY TO PVD.THIN MEMBRANE
CAUSING VMT.
3)OVIOUS ON THE CLINICAL EXAMINATION BUT OCT WILL HELP YOU
WITH THE ARCHITECTURE OF THE LESION.
4) COMPLETE PVD

74. 5)EPI-RETINAL MEMBRANE

75. • CAN PRESENT IN VARIOUS WAYS,GLOBALLY ADHERENT MEMBRANE
OVER THE ILM.
• PRESENTS AS CORRUGATED SURFACE THAT GIVES YOU THE CLUE
ABOUT THE MEMBRANE.

76. 6)VITREOMACULAR TRACTION

77. • VITREOMACULAR TRACTION LEADING TO FULL THICKNESS
MACULAR HOLE,VMT MUST BE DIFFERENTIATED FROM
VITREOMACULAR ADHESION IN WHICH VMA IS THE MACULAR
ATTACHMENT OF THE VITREOUS CORTEX WITHIN 3 MM RADIUS OF
THE FOVEA WITHOUT A CHANGE IN RETINAL
MORPHOLOGY,WHEREAS IN VMT THERE IS PRESENCE OF RETINAL
MORPHOLOGICAL CHANGES AS SEEN IN PICTURE A&B.
• C = FULL THICKNESS MACULAR HOLE.

78. B)INTRA-RETINAL PATHOLOGIES

79. 1)MACULAR EDEMA

80. • Cystoid macular edema= circular spaces around outer plexifom
layer,hyporeflective in nature inside retina and may be accompanied
by sub retinal fluid.
• Causes are retinal vein occlusion, uveitis, or diabetes. It most
commonly occurs after cataract surgery.

81. Diffuse edema resulting in cystoid intra-
retinal spaces not necessarily complete
thickening of the retina.
Globally adherent membrane causing a
diffuse macular edema .
Obvious membrane pulling the retina
resulting in Vitreo-macular traction.

82. 2)MACULAR HOLE
Macular hole less than 400
microns without VMA.
Impending macular hole
with RPE elevation at foveal
centre.
Macular hole with complete
PVD

83. 3)HARD EXUDATES

84. • Hard exudates are seen as hyperreflective spots seen intraretinally at
outerplexiform layer that produces shadowing on the deeper tissues.
• In picture A we can see some intra retinal and sub retinal fluids in this
scan.
• causes:Diabetic retinopathy.Hypertensive retinopathy.Coat's disease.

85. 4)COTTON WOOL SPOTS

86. • Focal or segmented areas of hyperreflectivity of the inner retinal layers
in the acute phase .
• Mostly confined to retinal nerve fiber layer with sparig of the outer-
retinal layers.
• Causes= ischaemic,immune and inflammatory conditions,infectious
,embolic,neoplastic etc.

87. 5)INTRA-RETINAL HAEMORRHAGES

88. 6)RETINAL DEGENERATIONS
Appreciable thinning of the outer nuclear layer (yellow
arrows)
The ellipsoid zone was seen to be attenuated in the parafoveal
region

89. 7)INNER & OUTER RETINALATROPHY
1 2
1)atrophy of the outer retina usually in case of wet armd.
2)atrophy of the inner retina usually secondary to inflammatory cascade like endophthalmitis.

90. 8)RETINOSCHISIS

92. 8)RADIATION RETINOPATHY

93. • Lymphoma treated with whole body radiation and bone marrow
transplant 9 years prior.RR phenotypically results from microvascular
occlusion and leaking capillaries between 6 and 36 months after
radiation exposure.
• Macular edema is an initial sign of RR detected on OCT.
• There might be a presence of microaneurysma without frank diabetic
retinopathy.

94. 9)PLAQUENIL TOXICITY
Early photoreceptor and outer retinal damage
spaceship sign

95. MEK inhibitor induced multifocal serous retinal
detachments.
Mitogen-activated protein kinase (MEK) inhibitors are a novel class of chemotherapeutic agents used to treat
metastatic melanoma by inhibiting the MEK enzyme

96. C) SUB-RETINAL PATHOLOGIES

97. 1)ARMD

98. • DRUSENS PRESENCE APPEARING AS UNDULATING AND ELEVATIONS
IN THE HYPER REFLECTIVE BAND OF THE RPE WITH LESS
REFLECTIVE MATERIAL BENEATH THEM.
• INNER RETINAL LAYERS REMAIN GENERALLY INTACT. DRUSENS ARE
LOCATED UNDER OR OCCASSIONALLY ABOVE THE RPE. BRUCH’S
MEMBRANE CAN BE VISIBLE.
• FOVEAL CONTOUR IS INTACT.

99. WET ARMD

100. • GROSS INTRA-RETINAL EDEMA ,EXUDATES AND SUB-RETINAL
HAEMORRHAGES.
• FLUID IN THE SUB RETINAL SPACE MAY BE PRESENT WHILE PRE
RETINAL & INTRA RETINAL HAEMORRHAGES ARE LESS COMMON.
• FIBROVASCULAR PED MIGHT ALSO BE PRESENT,DISCIFORM
SCARRING WITH SUB-RETINAL HYPERREFLECTIVE MATERIAL CAN
BE SEEN.

101. GEOGRAPHIC ATROPHY
There is loss of outer retinal layers including the RPE, EPIS line, COST line, ELM, and the outer nuclear
layer. The Bruch's membrane and choroidal capillaris is visible due to the overlying outer retinal atrophy.

102. 2)CENTRAL SEROUS RETINOPATHY
small PEDs and hyper-reflective, fibrinous sub-retinal fluid. RPE line is straight at the areas without
serous PED.

103. 3)PIGMENT EPITHELIAL DETACHMENT
OCT images of varying types of PED
in the same patient with AMD.
A) Drusenoid PED .
B) Serous PED.
C) Fibrovascular PED
(arrow) with overlying scant sub-
retinal fluid and adjacent small serous
PED.

104. 4)NEOVASCULARIZATION

105. • PROLIFERATIVE DIABETIC RETINOPATHY …WHITE
ARROW:hyperreflective loop extending from the optic disc into the vitreous
cavity. YELLOW ARROW=neovascular membrane with the central epiretinal
membrane.
• YELLOW ASTREIK: neovascular tractional membrane is visible temporally as a
preretinal hyperreflective sheet. PINK ASTREIK= intraretinal fluid
present. GREEN ASTERICK=traction-induced subretinal FLUID

106. 5)OUTER RETINAL TUBULATIONS
The hyperreflectivity of the shell, the relative hyporeflectivity of the inside of the tube and the
location within the ONL. ovoid hyporeflective spac.present in age-related macular degenerationes.

107. 6)RETINAL DETACHMENT

108. 7)CHOROIDAL NEOVASCULAR MEMBRANE

109. NOVEL OPTICAL COHERENCE TOMOGRAPHY FINDINGS

110. ADVANTAGES OF OCT
• Non-invasive, Non-contact
• Improved lesion detection.delineation,differentiation from normal tissues.
• Improved lesion characterization.
• No ionization radiation: Can be performed in pregnancy(2nd trimester onwards) &
young children.
• More repeatability.
• Tissue sections comparable to histopathology sections.

111. LIMTATIONS OF OCT
• Media opacities can interfere with optimal imaging.
• Unable to show the details of ciliary body & posterior surface of the Iris.
• Landmarks such as scleral spur and Schwalbe’s line are not as clearly visible as UBM.
• Automatic demarcation of the optic disc borders by the machine may be inaccurate.
• As with most diagnostic tests, patient cooperation is a necessity.
• Artifacts.
• The quality of the image is also dependent on the operator of the machine.
• Always in co-relation.

112. ARTIFACTS ON OCT
1) MIRROR ARTIFACTS:
• It occurs when the area of interest to be imaged crosses the zero delay line and
results in an inverted image.
2) VIGNETTING :
• This occurs when a part of the OCT beam is blocked by the iris and is
characterized by a loss of signal over one side of the image.

113. 3) MISALIGNMENT:
• This occurs when the fovea is not properly aligned during a volumetric scan.
4)OUT OF RANGE ERROR:
• Outer retina/choroidal image is cut off because of improper positioning of the
machine during image acquisition.

114. 5)BLINK ARTIFACT:
• Blink artifacts result in partial loss of data due to the momentary blockage of OCT
image acquisition. Blink artifacts are easily recognized as black horizontal bars
across the OCT image and macular map.
6)MOTION ARTIFACT:
• This occurs when there is movement of the eye during OCT scanning leading to
distortion or double scanning of the same area.
MULTIPLE OTHER ON OCT-A, TO BE DISCUSSED LATER

115. What is a clinically significant artifact?
• Any artifact resulting in automated segmentation errors of more than 10% of the
actual ETDRS center subfield thickness (CST) is considered as clinically
significant.
• Any artifact resulting in an error is more than 50 µm. This is based on a study of
reproducibility in STRATUS TD OCT.
• Artifacts resulting in misdiagnosis of retinal thickening or thinning are noted as
significant. Cutoffs are generated using published normative data for CIRRUS and
SPECTRALIS and by defining retinal thickening or thinning as the mean ± 2
standard deviations.

117. 1)PED 2)RD 3)CSR 4)ARMD

118. 1)RETINOSCHISIS 2)MACULAR HOLE 3)ERM 4)RD

119. 1)PTMH 2)EXUDATES 3)RETINAL PUCKER 4)CME

120. 1)PVD 2)VITREOUS HAEMORRHAGE 3)ERM 4) FIBROUS DEGENERATION

121. 1)CME 2)ARMD 3) FOREIGN BODY 4)DR

122. 1)PED 2)DRUSENS 3) HAEMORRHAGES 4)RP

123. 1)HARD EXUDATES 2)COTTON WOOL SPOTS 3)RD 4)CME

124. RECENT ADVANCES

125. 1) OCT ANGIOGRAPHY
• Optical coherence tomography angiography (OCT-A) , non-invasive technique for
imaging the microvasculature of the retina and the choroid.
• OCT-A technology uses laser light reflectance of the surface of moving red blood cells to
accurately depict vessels through different segmented areas of the eye, thus eliminating
the need for intravascular dyes.
• Spectral domain OCT (SD-OCT), with a wavelength of near 800nm; or a swept-source
OCT (SS-OCT), with wavelength, close to 1050nm.
• Currently, there are currently 4 main commercially available OCT-A devices:
 ZEISS Angioplex™ OCT
 Optovue AngioVue®
 Topcon®
 Heidelberg Engineering®

127. 2)VIS-OCT(OCT WITH VISIBLE LIGHT)
• Supercontinuum (SC) light source, which provides a smooth and powerful
broadband spectrum with good spatial coherence within the visible spectral range.
• The axial resolution is improved more by switching to visible light illumination.
• The highest axial resolution achieved using this method was 12.2 μm, and the
visible light spectrum covered 8 nm around 417 nm.
• Two major advantages:
Improved resolution.
Spectral imaging oximetry.

129. 3)OCT ELASTOGRAPHY (OCE)
• Optical coherence elastography (OCE) can provide clinically valuable information
based on local measurements of tissue stiffness.
• The assumptions commonly used to interpret displacement and strain
measurements in terms of tissue elasticity for static OCE and propagating wave
modes in dynamic OCE are discussed with the ultimate focus on OCT system
design for ophthalmic applications.
• Five dynamic OCE methods are considered in this comparative study. Each
method is classified by a vibration source configuration: Crawling waves method
Swept crawling wave
Standing wave method
Shear wave propagation
Tone-burst propagation

131. 4)POLARIZATION SENSITIVE OCT(PS-OCT)
• PS-OCT measures the polarization state of light and is based on the fact that some
tissues can change the polarization state of the probing light beam.
• Different mechanisms of Light–tissue interaction can cause such changes of the
polarization state: birefringence, diattenuation, and depolarization.
• Anterior eye segment imaging with PS-OCT: keratoconus, Anterior-chamber angle.
• PS-OCT in retinal imaging: macular region, optic nerve head and peripheral retina.

133. 5)OPTICAL COHERENCE TOMOGRAPHY
BLOOD FLOW
• OCT technique is capable of estimating functional characteristics of scanned
tissue such as tissue blood flow using Doppler OCT and OCT angiography.
• The optical frequency of light shifts when it scatters from moving red blood cells.
The amount of the shift is related to flow velocity, and this information provides a
noncontrast method to visualize and quantify retinal blood flow.
• While Doppler OCT provides data on total retinal blood flow, it is not sensitive
enough to examine the microcirculation with low-velocity blood flow.

135. 6)High-Resolution OCT (High-Res OCT)
7)Full-Field OCT (FFOCT) and Dynamic FFOCT (D-FFOCT)
8)Wide-Field and Ultrawide-Field OCT (WF-OCT and UWF-
OCT)
9)Hand-Held and Intraoperative OCT (iOCT)
10)At-Home OCT

136. EMERGING INNOVATIONS
• Photoacoustic ophthalmoscopy combined with OCT.
• Vertical-cavity surface emitting laser (VCSEL) technology.

137. 2)GLAUCOMA OVERVIEW MAP

138. SECTIONS OF THE REPORT
1) PATIENT DATA
2) FUNDUS IMAGE WITH RADIAL LINES OVERLYING THE OPTIC DISC
3) TSNIT MAP OF RNFL
4) TSNIT MAP OF NRR
5) QUADRANT MAP – RNFL
6) QUADRANT MAP-NRR
7) POSTERIOR POLE RETINAL THICKNESS MAP
8) POSTERIOR POLE GANGLION CELL THICKNESS MAP
9) HEMISPHERE ASYMMETRY & AVERAGE THICKNESS

139. 1)PATIENT DATA

140. 2) FUNDUS IMAGE WITH RADIAL LINES OVERLYING
THE OPTIC DISC

141. 3)TSNIT MAP OF RNFL

142. 4)TSNIT MAP OF NEURO RETINAL RIM

143. 5 & 6) QUADRANT MAP OF RNFL & NRR

144. 7 & 8) POSTERIOR POLE THICKNESS MAP OF
RETINAAND GANGLION CELLS

145. 9) HEMISPHERE ASYMMETRY & AVERAGE
THICKNESS

146. REFERENCES
• HANDBOOK OF RETINAL OCT,ELSEIVER 2013
• OCT ATLAS- HANGAI BY HEIDELBERG ENGINEERING 2014
• OPTICAL COHERENCE TOMOGRAPHY,KARGER 2014
• EYEWIKI
• AAO
• AOA
• INTERNET RESOURCES

147. THANK YOU!