nw2015 rcopt oct_retina22

Interpreting OCTs in

Common Macular Diseases

Nawat Watanachai

RCOPT : July 2015

» 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

How to get the best information

from macular OCT?

» 1. do the RIGHT scan

» 2. read the scan properly

from macular OCT?

» 1. do the RIGHT scan

» take the best image

» minimise all possible

error» 2. read the scan properly

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

Image Acquisition

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

• radial

OCT Basic Knowledge :

Scan Patterns for macula

• raster

• cruciate • single

radial line protocol

– 6X 6mm-long lines, 30’ apart

– Center at foveal center

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

raster scan protocol

Image acquisition

A. foveal split B. lamellar hole

A’ FTMH B’ FTMH

Retinal thickness map

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

» Depth 2 mm

» For thickness map

» Interpolation for thickness between sample point

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

» 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

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

» (R) manual retinal thickness measurement

» difference 51 mcm

Image acquisition

4. scan review software tool

from macular OCT?» 1. do the RIGHT scan

» 2. read the scan properly

» systematic approach

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

Retinal layers in OCT

»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

» 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

localization of missing photoreceptor

component

Jacobson 1998, 2000

cone-rod dystrophy, Best macular dystrophy

prediction of subret./ subRPE deposits

Aleman 2002, Pianta203

shadows

Let’s read

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

» identify inner and outer retinal boundaries

» good signal to noise ratio

» rescan?

» 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

» 1. retinal detachment

» RRD/ TRD/ ERD/ HRD

» 2. retinal thickening

» CSME/ CME/ CNV

» 3. RPED

» fibrous/ serous/ hemorrhage

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

» normal foveal profile

» slightly depression in the surface of

retina

loss of foveal depression

some problems

» deformations in the foveal profile

» VR surface

» ERM/ pseudohole

» MH/ Lamellar hole/ macular cyst

» Retina

» 2. rate overall acan profile

» 4. identify foveal cut» 5. structural assessment

» do we need rescan?

back to

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

» 5. structured assesment» alteration of layers

» Systematic : antpost

» 5. structured assesment : Preretinal/ Epiretinal

preretinal-vitreous cavity

syneresis/ VH

Epiretina

ERM/ MH

vitreo-retinal strands

vitreo-retinal traction

»5. structured assesment : Preretinal/ Epiretinal

» Vitreous assessment

» Search for opacities eg

» posterior hyaloid

» MH operculum51

» 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

A,B : PVD

C : VM traction

D. remodel after completion of PVD

» 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

» early MH

» oblique vitreofoveal tractional forces

» intrafoveal split

» Hee1995, Gaudric1999,

Haouchine2001, Tornambe2003 60

»5. structured assesment :

Preretinal/ Epiretinal

» early MH

» late MH

»5. structured assesment

: Preretinal/ Epiretinal

» FTMH: typical configuration

» round cystic margins

» SRF

»5. structured

assesment :

Preretinal/

Epiretinal

» 5. structured assesment: Intra-Retinal

1. macula edema

diffuse

cystoid

2. hard exudates

3. scar tissue

4. atrophic degeneration

» macula edema : Characteristics

» diffuse vs cystoid

» Central/symmetric vs asymmetric (eg RVO)

» Remember thickened retina can attenuate

signal

» Cystic space : Discrete area of

hyporeflectivity

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

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

» 5. structured

assesment:

» Intra-Retinal

» Retinal thinning

» Increase transmission of light to the deeper layer

» 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

thick/ thin/ edema

» 1. CNV

» 2. RPED

» 3. drusen

» 4. subretinal fibrosis

» 5. scar

» 6. RPE atrophy

» 7. SRF

» 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

clear SRF

» 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***

NOT so clear SRF?

A. 1st visit

B. 6 wks after

- drusen

- RPED

» 5. structured assesment: RPE/ sub-RPE

drusenSmall/ discrete low-lying areas of RPE elevation

c highly reflectivity

» RPED : area of hypo-reflectivity

underneath RPE elevation

» RPED

» Assess its size, contour and reflectivity

» Look for adjacent areas

» eg atrophy from RPE tear

Morphologic assessment : RPE elevation

» RPED : content

» serous/ hemorrhagic/ fibrovascular

some samples

2. 1 yr later after rx

the end

nw2015 rcopt oct_retina22

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