FUNDUS FLUORESCEIN ANGIOGRAPHY

SURAJ CHHETRIB.Optometry16th batchMaharajgung medical campus , Nepal

PRESENTATION LAYOUT• Introduction to fluorescein

• Basic principle of fluorescence• Some terminologies • Anatomical considerations • Indication and contraindication of FFA • Procedure of FFA• Normal phases of FFA • FFA interpretation• FFA Vs ICG• Phenomenon of FFA

INTRODUCTION OF FLUORESCEIN

• Orange water soluble dye

• When injected IV , it remains largely intravascular and circulates in blood stream

• 70 – 85 % of fluorescein bind with blood serum albumin

• Rest of remain free i.e unbound form

• Sodium fluorescein : C20 H10 O5 Na2

CONTINUE…• Properties

-Non-expensive-Non-toxic-Flouresces at blood PH level 7.37 – 7.45 -Rapid diffusion

• Synthesized from the petroleum derivatives resorcinol and phthalic anhydride

Chemically related to Phenolphthalein

• Molecular weight : 376 daltons

BASIC PRINCIPLE OF FLUORESCENCE

• Absorption followed by release of the radiant energy in the form of visible light

• Fluorescent substance follows Stokes lawStokes law

• Fluorescent substances absorbs light • Molecular excitation• Electrons elevated to higher less stable state Returns

to stable lower energy form Releasing light of longer wavelength FLUORESCENCE

• Entire process – 10 – 8 sec.

BASIC PRINCIPLE OF FLUORESCENCE

• Absorption spectrum of fluorescein – 465 to 490 nm• Excitation peak 490nm (blue part of spectrum )• Emission spectrum of fluorescein – 520 to 530 nm • Emission peak 530 nm (green-yellow spectrum )

NOTEAbsorbed radiant energy > emitted energy

AND As energy – inversely proportional to –wavelength SO, λ of emitted wave > λ of absorbed wave

FILTERS FOR PROCEDURE• Two type • 1) blue barrier filter• 2) yellow green barrier filter • Blue barrier filter ensures that only the blue light enters the eye

• Yellow green barrier filter blocks the blue light reflects from the eye • It allows green light to pass through unimpaired, to be recorded on the

film

TERMINOLOGIES Fluorescence- ability of a compound to absorb light of

shorter wavelength and emit light of longer wavelength with in a very short interval

Hyper-fluorescence – an area of abnormally high fluorescence due to increase density of dye molecule

Hypo-fluorescence - an area of abnormally poor fluorescence

Auto-fluorescence – an inherent property of a lesion to spontaneously fluoresce even in absence of dye

( observed before injection of the dye)

Arm retina circulation time- from dye injection to first appearance in retinal arteries( 10-12 sec)

Pooling- accumulation of dye in closed space .e.g. RPE detachment, CSR

Leakage- dye escapes in open space e.g. vitreous space

Window defect- type of early hyper-fluorescence due to RPE atrophy

Control photograph –photo taken before dye given to detect auto-fluorescence

Staining- late hyperfluorescence due to adsorption of the dye by a tissue

Blocked fluorescence – hypofluorescence occurs by masking underlying retinal and choroidal tissue by blood , pigment etc.

Capillary nonperfusion – due to non filling of the retinal capillaries due to anatomical and function reasons

Artifacts- undesirable shadows that are seen following the development of the film

ANATOMICAL CONSIDERATION• Major choroidal vessels are impermeable to both bound and unbound

form of fluorescein BUT Choriocapillaries • Walls are extremely thin • Contains multiple fenestrations • Through which free molecules pass across Bruchs membrane

Choriocapillaries and Bruchs membrane both permeable to free and bound fluorescein molecules

CONTINUE….• Outer blood retinal barrier : tight junction between RPE cells prevent

passage of fluorescein

• Inner blood retinal barrier : tight junctins between endothelium cells of retinal blood vessels prevent passage of fluorescein

• Fluorescein pass from choriocapillaries also passes through bruch’s membrane but it encounter with tight junction intracellular complex zonula occludens of RPE cells and prevent passage

• Disruption of barrier leak both bound and free fluorescein molecules

BLOOD VESSLES IN RETINA

• For FFA interpretation sensory retina divided into two layers 1. Inners vascular half ( ILM – INL ) Here retinal blood vessels located in two separate planes large retinal arteries and veins located in nerve fiber layer Retinal capillaries located in inner nuclear layer

2. Outer avascular half (OPL – RPE )• when retina becomes edematous ,• it is the layer that fluid accumulate causing the cystoid space

PURPOSE OF FULUROSCEIN ANGIOGRAPHY

• Studying the normal physiology of the retinal and choroidal circulation,as well as disease process affecting the macula.

• Evaluation of the vascular integrity of the retinal and choroidal vessels • Check the integrity of the blood ocular barrier.

- Outer blood retinal barrier breaks in CSR

- Inner blood retinal barrier breaks in NVD, NVE

CONTINUE…

• It helps in clinical diagnosis

• To determine extent of damage

• To formulate treatment strategy for choroidal and retinal disease

• To monitor result of treatment

INDICATION OF FFARetinal vascular malformation and tumors

Retinal vascular disorders

Macular disorders

Choroidal disorders

Optic nerve disorders

Retinal diseases1) Diabetic retinopathy2) Retinal vein occlusions3) Retinal artery occlusion4) Retinal vasculitis5) Coats disease6) Familial exudative

vitreoretinopathy

Macular diseases1) Central serous retinopathy2) RPE detachment3) Cystoid macular edema4) Macular hole5) ARMD6) Cone rod dystrophy7) Epiretinal membrane8) Vitiliform dystrophies9) Stargardts dystrophy

Retinal vascular malformations and tumors

1) Capillary hemangioma of retina2) Cavernous hemangioma of retina3) Retinal AV malformation 4) Congenital tortuosity of retinal vasculature5) Congenital hypertrophy of RPE6) Angioid streaks7) Astrocytic hamartoma

Choroidal lesions1) Choroidal neovascular (CNV)2) Hemangioma3) Nevus4) Melanoma5) Choroiditis6) Choroidal folds

Optic nerve disorders1) Optic atrophy2) Papilloedema3) Ischemic optic neuropathy4) Optic disc pit5) Optic disc drusen6) Optic disc hemangioma7) Melanocytoma8) Myelinated nerve fibers

CONTRAINDICATIONS ABSOLUTE1) known allergy to iodine containing compounds.2) H/O adverse reaction to FFA in the past.

RELATIVE1) Asthma2) Hay fever3) Renal failure4) Hepatic failure5) Pregnancy ( especially 1st trimester)

MILD MODERATE SEVERE

Staining of skin, sclera and mucous membrane

Nausea and vomiting

Respiratory- laryngeal edema,bhroncospasm

Stained secretionTear, saliva

Vasovagal response

Circulatory shock, MI, cardiac arrest

Vision tinged with yellow

utricaria Generalized convulsion

Orange-yellow urine

fainting Skin necrosis

Skin flushing, tingling lips pruritis

periphlebitis

COMPLICATIONS

COMPICATIONS MANAGEMENT• Unavoidable minor side effects : treatment not needed

• Temporary tan skin colour, Red after image from the photoflash and discoloration of the urine

• Transient Nausea and vomiting (10%): treatment not needed

• Vasovagal syncope (1%) :treatment not needed

• In extreme bradycardia • IV atropine may be needed.

CONTINUE..• Anaphylaxis such as bronchospasm, urticarial skin rash and

hypotension (<1%). • Treatment is with chlorpheniramine (piriton) 10mg IV, hydrocortisone

100mg IV

• Hypotension and Bronchospasm • oxygen and adrenaline 1ml of 1:1000 IM

• Cardiac and respiratory arrest (<0.01%)• Treatment would involve cardiopulmonary resuscitation

EQUIPMENT AND MATERIALS NEEDED FOR ANGIOGRAPHY

Fundus camera and auxilliary equipment

Matched fluorescein filters ( barrier and exciter )

Digital photoprocessing unit ( computer based )

23 gauge scalp vein needle

5 ml syringe

5 ml of 10% OR 3ml of 25 % fluorescein solution

20 gauge , 1.5 inch needle to draw the dye

Armrest for fluorescein injection

Tourniquet

Alcohol swabs

Bandage

Standard emergency equipment

PROCEDURE Patient is informed of the normal procedures, the side effects and the adverse

reactions.

Dilating the pupil

Made to sit comfortable.

3-4 red free photographs taken. (control photographs)

5ml of 10% or 3ml of 25% NAF injected through the anticubital vein

Wait for 8 seconds for young and 12 seconds for older patients ( normal arm-retina time)

Photos are taken at 1 second interval for 10 seconds

Then every 2 seconds interval for 30 seconds

Late photographs are usually taken after 3 ,5 and 10 minutes.

CIRCULATION OF DYE

Dye injected from peripheral vein

venous circulation

heart

arterial system INTERNAL CAROTID ARTERY

Ophthalmic artery Short posterior ciliary artery) Central retinal (choroidal circulation.) ( retinal circulation)

NORMAL PHASES IN FFA• Early phase

• Choroidal(prearterial)• Arterial• Arteriovenous (capillary)• Venous

• Early• mid• Late

• Mid phase• Late phase

CONTINUE…• Normally 10 -15 secs elapse between dye injection and arrival of dye

in the short ciliary arteries

• Choridal circulation preceeds retinal circulation by 1 Sec

• Transit- if dye through the retinal circulation takes approximately 15-20 secs

EARLY PHASE

• Choroidal filling through the short ciliary arteries • Initial patchy filling of lobules followed by diffused blush as

dye leaks out of choriocapillaries• Cilioretinal vessels and prelaminar vessels and prelaminar

optic disc capilaries fill

Choroidal ( prearterial ) phase

FACTS OF PATCHY CHOROIDAL FILLING• Choriocapillaries has number of lobules

• The lobules fill independently from one another,

• giving a transiently patched or blotched appearance

ARTERIAL PHASE

• Begins with the first appearance of fluorescein in the arteries, and extends until the arteries are completely filled

• Posterior pole fills with dye earlier than the periphery

• Superior branches usually fill first

Arterial phase

ARTERIO-VENOUS PHASE(CAPILLARY PHASE)

• Complete filling of retinal arteries and capillaries.

• Early laminar flow in the veins in which dye is seen along the lateral wall of the vein

• Choroidal fluorescence increases as free fluorescein continues to leak from the choriocapillaries

Arteriovenous phase

VENOUS PHASE

• Gradually whole diameter of the veins is filled

• Earliest seen in the peripapillary and macular region

• Divided according to the venous filling and arterial emptying • Early• mid• Late

EARLY VENOUS PHASE• Arteries and capillaries are completely filled and marked lamellar

venous flow

MID VENOUS PHASE

• Some veins are completely filled• Some shows marked laminar flow

LATE VENOUS PHASE• All veins are completely filled and the arteries beginning to empty

MID PHASE• Known as recirculation phase

• 2-4 min after injection

• Veins and arteries remain roughly equal in brightness.

• Intensity of fluorescein diminishes slowly as• flourescein is removed from the blood stream on the first pass through

the kidneys.

LATE PHASE• After 10-15 minutes little dye remains in the blood stream

• This phase demonstrates• Gradual elimination of the dye from the retinal and choroidal

vasculature

• staining of optic disc , sclera is normal finding

• Any other hyperfluoresecence suggest the presence of abnormality

Late Phase

Phases of angiogram Time ( in seconds)Injection 0Posterior ciliary artery 9.5Choroidal phase 10Arterial 10 - 12Arterio venous 13Early venous 14 - 15Mid venous 16 -17Late venous 18 – 20Late ( elimination) 5 minutes

FLUORESCENCE IN FOVEAL REGION

• Dark appearance WHY? i) Avascularity in the FAZii) Blockage of the choroidal

flourescein because of• increased amount of xanthophyll

pigments at fovea• melanin in RPE

NORMAL ANGIOGRAM

• Patchy filling of choroid • Retinal blood vessels filling• Dark area of foveal avascular zone• But there is no hyper or hypofluroscence area • At the end of the transit phase, fluorescein dye remains in the choroid

and sclera due to leakage from the choroidal vessels• A small amount of fluorescein also remains in the optic nerve head and

retinal vessels, but there is no leakage• Any additional fluorescein in the eye should be regarded as pathologic

NORMAL ANGIOGRAM

STEPWISE APPROCH TO FFA• A fluorescein angiogram should be interpreted

systematically to optimize diagnostic accuracy as follows:-

• A ) Indicate whether images of right , left or both eyes have been taken.

• B)comment on the red free images

• C)indicate any delay in filling as well as hyper or hypo fluorescence

• D)indicate any characteristic features such as a smoke –stack or lacy filling pattern.

• E)indicate any evolution through the course of the angiogram in the area or intensity of fluorescence.

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FFA INTERPRETATION FLOW CHART Fluorescein angiogram

Normal Abnormal Auto/pseudofluorescence

Hyperfluorescence Hypofluorescence

Leakage Pooling Staining Window Blocked Non

defect filling

NOTE• Hyperfluorescence and hypofluorescence can alternate in same

location

• Especially in inflammatory disorder

• 1st hypofluorescence due to retinal oedema

• Later hyperfluorescence due to increased vascular permeability

AUTOFLUORESENCE• Emission of fluorescence light in the absent of fluorescein

Example : optic nerve head drusen , astrocytic hematoma , myelinated nerve fibers

Optic disc drusen Astrocytic hematoma

PSEUDOFLUORESCENCE• Occurs when nonfluorescence light passes through the entire filter system • Blue reflected light passes from green filter pseudofluorescence occurs

• It decrease contrast aswell as resolution of image

• To avoid pseudofluorescence filter combination to be sure that no significant overlap exists

• Over the time filter alter the range of light transmission so should be change in certain time . Auther recommend about 5 year time to change filter

WINDOW DEFECT• Focal RPE atrophy • Unmasking of normal background of choroidal fluorescence

• Characterized by early hyperfluorescence which increases in intensity then fade without changing shape and size

e.g. inflammation of RPE atrophy of RPE , drusen

EXTRAVASCULAR LEAK• Pooling and staining in choroid • Cystoid edema and noncystoid edema in retina • Neovascularization , inflammation and tumor vessels in vitreous • Disc staining

Cystoid oedema of macula

Pooling( accumulation of dye in a closed space)

-Early hyperfluorescence sub-retinal space Early hyperfluorescence sub RPE space increase in size ,intensity increase intensity only e.g. CSR e.g. PED

POOLING OF DYE

CSR( sub RETINAL space)PED( sub RPE space)

CSR increase in size and intensity

NVD

NVE

STAINING• Accumulation of fluorescence within a tissue

• Due to prolonged dye retention

• Minimum hyperfluorescence in early and midphase which increases in late phase

• Can be seen in normal as well as pathologically altered tissue

examples

RETINALa. non-cystoid macular oedema

b. Perivascular staining

SUB RETINAL Drusens Sclera Lamina cribrosa scars

Drusens in ARMD

LATE HYPERFLUROSCENCE ALONG THE EDGE OF GEORAPHIC SCAR

FOCAL EXUDATIVE

• Circumscribed retinal thickening• Associated complete or incomplete circinate hard exudates

• Focal leakage on FA

Optic Disc Swelling

HYPOFLURESCENCE

• Reduction or absence of fluorescein

• Two causes

BLOCKED FLUORESCENCE

VASCULAR FILLING DEFECTS

BLOCKED FLUORESCENCE

• Optical obstruction (masking) of normal density of fluorescein• Caused by lesions anterior to retina

• Pre-retinal lesions eg.vitreous opacity,preretinal haemorrhage block all fluorescence

• Deep retinal lesions eg.intraretinal haemorrhage and hard exudates block only capillary fluorescence

• Increased density of RPE eg.congenital hypertrophy

• Choroidal lesions eg.naevus

EXAMPLE

FILING DEFECTS• Inadequate perfusion of tissue with resultant low fluorescein content

• Avascular occlusion of choroidal circulation or retinal arteries,veins and capillaries

• Loss of vascular bed eg.severe myopic degeneration – choroideremia

• Emboli

• arteriosclerosis

EXAMPLE

CRAOCRVO

LIMITATIONS OF FFA

1) Does not permit study of choroidal circulation details due to

a) melanin in RPE b) low mol. Wt. of fluorescein how to overcome ---- ICG

2) More adverse reaction

3) Inability to obtain angiogram in patient with excess hemoglobin or serum protein

INDOCAINE GREEN ANGIOGRAPHY

• FFA excellent method for demonstrating retinal circulation.

• But…• Not helpful in delineating choroidal circulation

• ICG –of particular value in studying choroidal circulation ,

• Can be useful adjunct to FA in investigation of macular diseases.

FFA Vs ICGPARAMETERS FFA ICG

1) Dye used Sodium fluorescein

Indocyanine green

2) Light used visible spectrum infrared

3) purpose study retinal vasculature

Choroidalvasculature

4) Filter used Blue- green Infra-red

5) expense lower higher

PHENOMENON OF FFA• All the process of occurrence of hyper or hypo-fluorescence can be

described under following 3 phenomenons

A. OPTICAL PHENOMENON

B .MECHANICAL PHENOMENON

C. DYNAMIC PHENOMENON

OPTICAL PHENOMENON• Normal neurosensory retina is transparent

• Normal RPE and Bruch’s Membrane are semitransparent

• Hence, we can see choroidal fluorescence

• BUT, this transparency can be pathologically increased or decreased

DECRESEING TRANSPARENCY • In case of blocked fluorescence , transparency is lost

• SO, WE DO NOT SEE CHOROIDAL FLUORESCENCE

Accumulation of blood haemorrhage

RPE hypertrophyChoroidal naevus

INCRESING TRANSPARENCY

• In case of staining due to drusens,angioid streaks ,scars and degenerative processes

Accumulation of drusens under RPE

MECHANICAL PHENOMENON• Related to adhesion of RPE to Bruch’s Membrane

• RPE firmly attached to Bruch’s membrane by hemidesmosomes

Absence of hemidesmosomes

RPE splits away from Bruch’s membrane

Fluorescein stained fluid accumulate in between them eg. PIGMENT EPITHELIAL DETACHMENT

DYNAMIC PHENOMENON• Related to diffusion of fluorescein in ocular tissue• Determined by inner and outer blood retinal barrier I.E DIFFUSION

BARRIER

RETINAL VESSELS• Normal retinal vessels do not leak fluorescein - due to zonula

occludents in between endothelial cells

• These zonula occludents open up during inflammatory process

Zonula occludents open up

normal

Endothelial cell is lost

Pores in endothelial cells

PERIVASCULITIS

DIABETIC MICROANEURYSM

PROLIFERATED RETINAL VESSELS

RETINAL PIGMENT EPITHELIUM• Normal RPE is tight

• zonula occludens seal portion of all the intercellular spaces of the pigment epithelial monolayer.

Cental serous chorioretinopathy

Haemorrhagic PED in wet ARMD

REFERENCES

INTERNATE

•Thank you