Nw2015 rcopt oct_retina22

Interpreting OCTs in

Common Macular Diseases

Nawat Watanachai

RCOPT : July 2015

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» 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

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How to get the best information

from macular OCT?

» 1. do the RIGHT scan

» 2. read the scan properly

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from macular OCT?

» 1. do the RIGHT scan

» take the best image

» minimise all possible

error» 2. read the scan properly

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Image

Acquisition

1. centralization

– pts c good vision : easy

– Pts c poor fixation : hard

• Identify the fovea location

• Place the scan on it correctly5

Image Acquisition2. Data verification and validation

– Do it at the end of scanning session

– error in the retinal boundary delineation

– re-do the scan

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Image Acquisition

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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 acquisition3. raster scanning

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• radial

OCT Basic Knowledge :

Scan Patterns for macula

• raster

• cruciate • single

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radial line protocol

– 6X 6mm-long lines, 30’ apart

– Center at foveal center

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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

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raster scan protocol

Image acquisition

A. foveal split B. lamellar hole

A’ FTMH B’ FTMH

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Retinal thickness map

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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

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» Depth 2 mm

» For thickness map

» Interpolation for thickness between sample point

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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

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» 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

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Retinal Thickness

» (L) automated retinal thickness measurement (VR-IS/OS)

» (R) manual retinal thickness measurement

» difference 51 mcm

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Image acquisition

4. scan review software tool

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from macular OCT?» 1. do the RIGHT scan

» 2. read the scan properly

» systematic approach

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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

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Retinal layers in OCT

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»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

»Intermediate reflectivity : plexiform layers»Low reflectivity : nuclear layers/ photoreceptor outer segment/ vitreous

»Fovea

»Absence of inner retinal layer

»Increased thickness of the photoreceptor layer25



»High reflectivity : NFL/ RPE/ choriocapillatis

»Intermediate reflectivity : plexiform layers

»Low reflectivity : nuclear layers/ photoreceptor outer segment/ vitreous»Fovea

»Absence of inner retinal layer

»Increased thickness of the photoreceptor layer26



• 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

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» 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

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shadows

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Let’s read

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Morphologic assessment

» 1. determine scan quality

» 2. rate overall scan profile

» 3. evaluate foveal profile

» 4. identify foveal cut

» 5. structural assessment33


» 1. determine scan quality» 2. rate overall acan profile



» 5. structural assessment

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» identify inner and outer retinal boundaries

» good signal to noise ratio

» rescan?

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» 2. rate overall scan profile» 3. evaluate foveal profile


» 5. structural assessment36


» normal over-all retinal profile

» slightly concave curvature

» abnormal

» exaggerated concavity and

convexity or retinal folds

» watch for artefact

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» 1. retinal detachment

» RRD/ TRD/ ERD/ HRD

» 2. retinal thickening

» CSME/ CME/ CNV

» 3. RPED

» fibrous/ serous/ hemorrhage

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» 3. evaluate foveal profile» 4. identify foveal cut


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» normal foveal profile

» slightly depression in the surface of

retina

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loss of foveal depression

some problems

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» deformations in the foveal profile

» VR surface

» ERM/ pseudohole

» MH/ Lamellar hole/ macular cyst

» Retina

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» 2. rate overall acan profile


» 4. identify foveal cut» 5. structural assessment

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» do we need rescan?

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back to

Image

Acquisition

1. centralization

• Identify the fovea location

• Place the scan on it correctly

– Centre line tool(OCT3 software) : right

click45



» 2. rate overall acan profile




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» 5. structured assesment» alteration of layers

» Systematic : antpost

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» 5. structured assesment : Preretinal/ Epiretinal

preretinal-vitreous cavity

syneresis/ VH

Epiretina

ERM/ MH

vitreo-retinal strands

vitreo-retinal traction

NVE

NVD

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»5. structured assesment : Preretinal/ Epiretinal

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» Vitreous assessment

» Search for opacities eg

» posterior hyaloid

» MH operculum51


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» 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

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A,B : PVD

C : VM traction

D. remodel after completion of PVD

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» 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

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VMT

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ERM

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ERM

» early MH

» oblique vitreofoveal tractional forces

» intrafoveal split

» Hee1995, Gaudric1999,

Haouchine2001, Tornambe2003 60


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»5. structured assesment :

Preretinal/ Epiretinal

» early MH

» late MH

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»5. structured assesment

: Preretinal/ Epiretinal

» FTMH: typical configuration

» round cystic margins

» SRF

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»5. structured

assesment :

Preretinal/

Epiretinal

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» 5. structured assesment: Intra-Retinal

1. macula edema

diffuse

cystoid

2. hard exudates

3. scar tissue

4. atrophic degeneration

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» macula edema : Characteristics

» diffuse vs cystoid

» Central/symmetric vs asymmetric (eg RVO)

» Remember thickened retina can attenuate

signal

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» Cystic space : Discrete area of

hyporeflectivity

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

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

edema

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» 5. structured

assesment:

» Intra-Retinal

» Retinal thinning

» Increase transmission of light to the deeper layer

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» 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

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thick/ thin/ edema

» 1. CNV

» 2. RPED

» 3. drusen

» 4. subretinal fibrosis

» 5. scar

» 6. RPE atrophy

» 7. SRF

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» 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

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clear SRF

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» 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***

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NOT so clear SRF?

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A. 1st visit

B. 6 wks after

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- drusen

- RPED

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» 5. structured assesment: RPE/ sub-RPE

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drusenSmall/ discrete low-lying areas of RPE elevation

c highly reflectivity

» RPED : area of hypo-reflectivity

underneath RPE elevation

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» RPED

» Assess its size, contour and reflectivity

» Look for adjacent areas

» eg atrophy from RPE tear

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Morphologic assessment : RPE elevation

» RPED : content

» serous/ hemorrhagic/ fibrovascular

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some samples

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1021

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2. 1 yr later after rx

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the end

Health & Medicine

Nw2015 rcopt oct_retina22