Akbar Etesam Por MD VITRORETINAL FLOWSHIP

FA –ICG OCT IN ARMD

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

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.

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

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.

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

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

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

Recurrent Choroidal New Vessel A. Late Phase Fluorescein Angiography B Recurrent Choroidal New Vessel A. Late Phase Fluorescein Angiography B. Late Phase ICG Angiography

OCT

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.

Retinal layer scanning

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

Reflectivity Increased : inflammatory infiltrate, fibrosis, exudates and hemorrhage Decreased reflectivity : retinal edema, hypopigmentation of the RPE decreased uniformly :abnormalities of the media )small pupil (

ARMD

ARMD tayps Soft drusen-Geographic atrophy Classic CNV Occult CNV Fibrovascular pigment epithelium detachment Retinal angiomatous proliferation Polypoidal choroidal vasculopathy

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

Soft druen

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

CNV

CLASSIC CNV direct exudative symptoms indirect exudative symptoms

Direct Exudative Symptoms: a hyper-reflective,fusiform area of thickening, above and adjacent to the RPE The shadowing underneath the RPE towards the choroid

Direct exudative symptom

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)

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

FIBROVASCULAR PIGMENT EPITHELIUM DETACHMENT A thicker hyper-reflectivity notch appended on the choroidal side of the elevated retinal pigment epithelium might represent CNV

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

A distinct form of occult CNV associated with proliferation of intraretinal capillaries in the paramacular area

POLYPOIDAL CHOROIDAL VASCULOPATHY A unique form of occult choroidal neovascular membrane

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

Prognosis Generally good, provided the macula is not involved

Conclusion: Helping in categorization Picking up the associated secondary changes Monitoring response to the therapies

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