Nw2015 rcopt oct_retina22

Interpreting OCTs in
Common Macular Diseases
Nawat Watanachai
RCOPT : July 2015
1

» pros of FDOCT
– accurate
– reproducible
– non invasive
– fast
» good in
– diagnosis
– gold std in some diseases
– monitor objectively
– retinal thickness measurement
– fluid collection
why OCT
2

How to get the best information
from macular OCT?
» 1. do the RIGHT scan
» 2. read the scan properly
3

from macular OCT?
» take the best image
» minimise all possible
error
4

Image
Acquisition
1. centralization
– pts c good vision : easy
– Pts c poor fixation : hard
• Identify the fovea location
• Place the scan on it correctly 5

Image Acquisition
2. Data verification and validation
– Do it at the end of scanning session
– error in the retinal boundary delineation
– re-do the scan
6

Image Acquisition
7
2. Data verification and validation
– Verify centralizationof the 6 scans
– Retinal map(single eye), retinal
thickness/volume (OU) analyze protocols
»SD should be around 0 mcm
»SD > 30 mcm
» poor centration
» do the scan again

Image acquisition
3. raster scanning
8

• radial
OCT Basic Knowledge :
Scan Patterns for macula
• raster
• cruciate • single
9

radial line protocol
– 6X 6mm-long lines, 30’ apart
– Center at foveal center
10

3. raster scanning
– to minimize the chance of missing morphological
details
– 8 mm length scan
– best for vitreomacular adhesion
– May hit small lesions that missed on radial
protocol
11
raster scan protocol

Image acquisition
A. foveal split B. lamellar hole
A’ FTMH B’ FTMH
12

Retinal thickness map
13
color Thickness (microns)
White >470
red 350-470
Orange 320-350
Yellow 270-320
Green 210-270
blue 150-210
» from radial scan

Retinal Thickness
» 1. fundamental of OCT automatic retinal thickness
measurement
– algorithm (math. calculation)
– presumes 2 high reflective structures
• 1. VR surface
• 2. RPE-photoreceptor outer segment interface
– compares the shape of 1 a-scan to adjacent a-scans 14

Retinal thickness map
15
» Depth 2 mm
» For thickness map
» Interpolation for thickness between sample point

16
Retinal Thickness
machine can be error

» 2. software delineation of outer neuro-sensory
retinal boundary
» HRL
– TDOCT : RPE-choriocapillaries reflective complex
– SDOCT : 2 lines
• IS/OS junction
• RPE-choriocapillaries reflective complex
Retinal Thickness
17

» 2. software delineation of outer neuro-
sensory retinal boundary
» SDOCT sometimes detect innerHRL as
outer boundary of retina
• error in thickness measurement
• may need manual caliper-assisted
technique
– auto VS manual differed by 9.9-38%
• Costa 2004
Retinal Thickness
18

Retinal Thickness
» (L) automated retinal thickness measurement (VR-IS/OS)
» (R) manual retinal thickness measurement
» difference 51 mcm
19

Image acquisition
4. scan review software tool
20

from macular OCT?
» systematic approach
21

Basic Principles in OCT reading
» Know your retinal histo/histopathology
» Know what is normal : contour/ thickness
» Remember you’re dealing with
» light and its wave properties
» Reflections/ interfaces
» Attenuation/ shadowing
» Always consider image quality/ artefacts
22

Retinal layers in OCT
23

»High reflectivity : NFL/ IS-OS Junction/ RPE-choriocapillaris
»Intermediate reflectivity : plexiform layers
»Low reflectivity : nuclear layers/ photoreceptor outer segment/ vitreous
»Fovea
»Absence of inner retinal layer
»Increased thickness of the photoreceptor layer 24

»High reflectivity : NFL/ RPE/ choriocapillatis
»Fovea
»Increased thickness of the photoreceptor layer
25

»High reflectivity : NFL/ RPE/ choriocapillatis
»Fovea
»Increased thickness of the photoreceptor layer 26

• defining inner and outer HRL
• HRL - Highly Reflective Layer
• TD OCT : single line
• FD OCT : 2 lines 27

• defining inner and outer HRL
• FD OCT : not 1 line, but 2
• inner line : IS/OS junction
• outer line : RPE choriocapillaris complex
28

» IS/OS junction
» correlated with VA
» irregularities at the level of inner HRL after MH Sx
prevent VA improvement
» Uemoto 2002, Kitaya 2004, Villate 2005.
29

IS/OS junction : correlated with VA
RP
localization of missing photoreceptor
component
Jacobson 1998, 2000
cone-rod dystrophy, Best macular dystrophy
prediction of subret./ subRPE deposits
Aleman 2002, Pianta203
30

shadows
31

Morphologic assessment
» 1. determine scan quality
» 2. rate overall scan profile
» 3. evaluate foveal profile
» 4. identify foveal cut
» 5. structural assessment
33

» 2. rate overall acan profile
34

» identify inner and outer retinal boundaries
» good signal to noise ratio
» rescan?
35

36

» normal over-all retinal profile
» slightly concave curvature
» abnormal
» exaggerated concavity and
convexity or retinal folds
» watch for artefact
37

» 1. retinal detachment
» RRD/ TRD/ ERD/ HRD
» 2. retinal thickening
» CSME/ CME/ CNV
» 3. RPED
» fibrous/ serous/ hemorrhage
38

39

» normal foveal profile
» slightly depression in the surface of
retina
40

loss of foveal depression
 some problems
41

» deformations in the foveal profile
» VR surface
» ERM/ pseudohole
» MH/ Lamellar hole/ macular cyst
» Retina
42

43

» do we need rescan?
44

back to
Image
Acquisition
1. centralization
• Identify the fovea location
• Place the scan on it correctly
– Centre line tool(OCT3 software) : right
click
45

46

» 5. structured assesment
» alteration of layers
» Systematic : antpost
47

» 5. structured assesment : Preretinal/ Epiretinal
preretinal-vitreous cavity
syneresis/ VH
Epiretina
ERM/ MH
vitreo-retinal strands
vitreo-retinal traction
NVE
NVD
48

49
»5. structured assesment : Preretinal/ Epiretinal

50

» Vitreous assessment
» Search for opacities eg
» posterior hyaloid
» MH operculum
51

52

53
» consider looking for ERM/ PVD
traction in difficult DME cases

DME: high prevalence of perifoveal PVD
Gaucher 2005
favorable macular remodeling in DME
after spontaneous PVD
Watanabe 2000, Yamagachi 2003
54

A,B : PVD
C : VM traction
D. remodel after completion of PVD
55

» Look for areas of abnormal VMT
» Identified areas where thin
hyperreflective band from the vit insert
into the retina
» Look for ERM
» Thin hyperreflective structures which
show multiple areas of attachment and
separation from the inner retinal surface
» may demonstrate free posterior hyaloid
face
56

57
VMT

58
ERM

59
ERM

» early MH
» oblique vitreofoveal tractional forces
» intrafoveal split
» Hee1995, Gaudric1999,
Haouchine2001, Tornambe2003 60

61
»5. structured assesment :
Preretinal/ Epiretinal
» early MH

» late MH
62
»5. structured assesment
: Preretinal/ Epiretinal

» FTMH: typical configuration
» round cystic margins
» SRF
63

64
»5. structured
assesment :
Preretinal/
Epiretinal

» 5. structured assesment: Intra-Retinal
1. macula edema
diffuse
cystoid
2. hard exudates
3. scar tissue
4. atrophic degeneration
66

» macula edema : Characteristics
» diffuse vs cystoid
» Central/symmetric vs asymmetric (eg RVO)
» Remember thickened retina can attenuate
signal
67

» Cystic space : Discrete area of
hyporeflectivity
68

Case courtesy of Dr. Scott Lee, East Bay Retina Consultants, Oakland, CA, USA
69

Mid-retina slab enface view emphasizes the presence of hard exudates in a subject with mild macular
edema
70

71

72

73
» 5. structured
assesment:
» Intra-Retinal

» Retinal thinning
» Increase transmission of light to the deeper layer
74

75
» Retinal thinning
» mostly found in late stage of many
diseases

IS/OS-Ellipsoid Enface Slab: Hydroxychloroquine toxicity example with classic bull’s eye
maculopathy
Case courtesy of Dr. Scott Lee, East Bay Retina Consultants, Oakland, CA, USA
76

77
thick/ thin/ edema

» 1. CNV
» 2. RPED
» 3. drusen
» 4. subretinal fibrosis
» 5. scar
» 6. RPE atrophy
» 7. SRF
78
» 5. structured assesment: sub-retina

» Separation between neural retina and RPE
» Generally hyporeflective
» Look for associated RPE level change eg
small PED in CSR
» Partial preservation of foveal depression
79
clear SRF

81

» Not hyporeflective space
» Presence of tissue eg typeII CNV,
subretinal fibrosis
» Hemorrhage or lipid
» Viscous SRF eg fibrinous CSR
» Correlate with color fundus photo/ FA/
ICG***
82
NOT so clear SRF?

83

84
A. 1st visit
B. 6 wks after

85

- drusen
- RPED
87
» 5. structured assesment: RPE/ sub-RPE

88
drusen
Small/ discrete low-lying areas of RPE elevation
c highly reflectivity

» RPED : area of hypo-reflectivity
underneath RPE elevation
89

» RPED
» Assess its size, contour and reflectivity
» Look for adjacent areas
» eg atrophy from RPE tear
90

Morphologic assessment : RPE elevation
» RPED : content
» serous/ hemorrhagic/ fibrovascular
91

Nw2015 rcopt oct_retina22

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