Akbar Etesam Por MD - PowerPoint Presentation

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Akbar Etesam Por MDVITRORETINAL FLOWSHIP

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FA –ICG OCT

IN ARMD

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Angiography

Angiography is a diagnostic test used by ophthalmologists to photograph structures in the back of the eye and is especially useful in finding

damage to the blood vessels

, which nourish the retina. There are two types of angiography:

fluorescein

and

indocyanine

green

(ICG).

Fluorescein

angiography is used primarily to study blood circulation in and just beneath the surface of the retina

, while

ICG angiography is better for photographing the deeper

choroidal

vessels

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ICG Angiography

Indocyanine

green

(ICG) is an intravenous dye which has been used for many years to study

blood flow in the heart

. In the past several years, techniques have been developed to use ICG to image ocular blood vessels, the

choroid

. Leaky or abnormal blood vessels in the choroid are a common problem for people with macular degeneration, but traditional

fluorescien

angiography is sometimes unable to clearly identify these abnormal blood vessels under the retina

. Because of its unique properties, ICG is able to delineate this process more clearly in as many as

40% of patients in whom

fluorescein

angiography is inconclusive

.

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ICG BASICS

ICG absorbs light in the

near-infrared range

of 790 nm to 805 nm. The emission spectrum ranges from 770 nm to 880 nm, peaking at 835 nm. The physical characteristics of ICG allow for visualization of the dye through overlying

melanin

and

xanthophyl

. ICG molecule is larger (molecular weight,

775 d vs. 332

d for

fluorescein

) and more protein-bound in plasma than is

fluorescein

and fluoresces in the infrared spectrum

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I C G angiography

The activity of ICG in the near-infrared light also allows visualization through

serosanguineous

fluid

, shallow

hemorrhage

,

pigment

and

lipid

exudate

The result is enhanced imaging of conditions such as

choroidal

neovascularization

and

pigment epithelium detachment

. Images are usually taken at intervals at least up to

thirty minutes

, and perhaps as long as

an hour

after the injection.

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F A – I C G

ICG angiography was performed with infrared photographic film. However, the

poor sensitivity of film

coupled with the

relatively weak fluorescence

properties of the dye caused this method to be abandoned. The strong binding of ICG dye to plasma proteins Because it has both

lipophilic

and hydrophilic properties, (

ICG is 98% protein-bound in vivo

) results in slow leakage as compared with

fluorescein

and reduces the amount of

extravascular

fluorescence available for imaging.

Digital video

cameras

have been used to capture images for ICG angiography. This has made ICG angiography a useful clinical diagnostic tool, particularly for imaging of

subretinal

neovascular

membranes

in cases where such membranes can

not be adequately imaged with

fluorescein

angiography

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High speed angiography of a patient with choroidal neovascularization (white arrows) demonstrates clearly the perfusing and draining feeder vessels (black arrow).

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Fluorescein angiography reveals occult choroidal neovascularization. Fig. 3B: Late phase ICG angiogram shows a well-defined plaque.

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Recurrent Choroidal New VesselA. Late Phase Fluorescein AngiographyB. Late Phase ICG Angiography

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OCT

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How the OCT work

The OCT uses an interferometer that measures the time it takes for light to be reflected back from structures in the retina, as compared to the time it takes for light to be reflected back from a reference mirror at specific distances.  The process is similar to that of

ultrasonography

, except that light is used instead of sound waves

.

 

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Retinal layer scanning

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REFLECTIVITY

Highly reflective structures are represented by

red.NFL,RPE

Medium reflections appear yellow or

green MIDLE RETINAL layer

structures with low reflectivity are blue

Black signal designates the absence of a reflective

signal.PHOTORESEPTORS

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Reflectivity

Increased

:

inflammatory infiltrate, fibrosis, exudates and hemorrhage

Decreased reflectivity

:

retinal edema,

hypopigmentation

of the RPE

decreased uniformly

:

abnormalities of the media

)

small pupil

(

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ARMD

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ARMD tayps

Soft

drusen

-Geographic atrophy

Classic CNV

Occult CNV

Fibrovascular

pigment epithelium detachment

Retinal

angiomatous

proliferation

Polypoidal

choroidal

vasculopathy

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SOFT DRUSEN

Localized multiple elevation of the hyper-reflective band of the retinal pigment epithelium-

bruch's

membrane-

choriocapillaris

complex

With no shadowing backwards to choroid

Neither any sub-retinal nor intra-retinal fluid accumulation

The different retinal layers remain normally organized

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Soft druen

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GEOGRAPHIC ATROPHY

A decrease in thickness of the

neurosensory

retina

A disappearance of the

hyporeflective

band corresponding to the photoreceptors

An increased hyper-reflectivity of the retinal pigment epithelium-Bruch's membrane-

choriocapillaris

extending back towards the underlying choroid

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CNV

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CLASSIC CNV

direct

exudative

symptoms

indirect

exudative

symptoms

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Direct

Exudative

Symptoms:

a hyper-

reflective,fusiform

area of thickening, above and adjacent to the RPE

The shadowing underneath the RPE towards the choroid

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Indirect

Exudative

Symptoms:

increase of thickness of the sensory retina due to intra-retina fluid accumulation

flattening of the

foveal

depression

Detachment and elevation of the

neurosensory

retina

RPE detachment (serous or hemorrhagic)

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OCCULT CNV

A hyper-reflective thickened band confounded with the RPE usually irregular and sometimes

fusiform

(cigar-like) with shadowing towards the choroid

RPE detachment

Sub-retinal and/or intra-retinal accumulation of serous fluid with or without

intraretinal

cystoid

edema

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FIBROVASCULAR PIGMENT EPITHELIUM DETACHMENT

A thicker hyper-reflectivity notch appended on the

choroidal

side of the elevated retinal pigment epithelium might represent CNV

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RETINAL ANGIOMATOUS PROLIFERATION

Deep retinal

neovascularization

The retinal

neovascularization

eventually communicates with the

subretinal

and

choroidal

space

Choroidal

neovascularization

is present in late-stage RAP

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A distinct form of occult CNV associated with proliferation of

intraretinal

capillaries in the

paramacular

area

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POLYPOIDAL CHOROIDAL VASCULOPATHY

A unique form of occult

choroidal

neovascular

membrane

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1. A branching network of inner

choroidal

vessels

2. Terminal,

aneurysmal

dilations of the vessels

3. Subtle nodular

choroidal

protrusions

4.

Serosanguineous

retinal pigment epithelial detachments

5.

Exudative

retinopathy

6.

Vitreal

hemorrhage

7. Chronic and recurrent course

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Prognosis Generally good, provided the macula is not involved

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Conclusion:

Helping in categorization

Picking up the associated secondary changes

Monitoring response to the therapies

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THE END

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