RYAN VOLUME 1 - FLUORESCEIN ANGIOGRAPHY Flashcards
WHAT PRINCIPLE IS FA BASED ON? HOW TO EXPLAIN IT?
LUMINESCENCE - SPONTANEOUS EMISSION OF LIGHT FROM ANY SOURCE OTHER THAN HEAT AND OCCURS WHEN ENERGY IS ABSORBED AND THEN EMMITTED AT ANOTHER FREQUENCY.
LIGHT IS ABSORBER -> FREE ELECTRONS ELEVATED INTO HIGHER ENERGY STATES -> ENERGY REEMITTED BY SPONTANEOUS DECAY INTO LOWER ENERGY GROUND STATES.
ALWAYS A SHIFT FROM A SHORTER WAVELENGHT (MORE ENERGY) TO A LONGER WAVELENGHT (LESS ENERGY).
WHAT IS FLUORESCENCE?
A FORM OF LUMINESCENCE. IT IS MAINTAINED ONLY BY CONTINUOUS EXCITATION. EMISSION STOPS AS SOON AS EXCITATION STOPS. IT DOES NOT HAVE AN AFTERGLOW.
WHAT IS THE SODIUM FLUORESCEIN?
IT IS A HYDROCARBON THAT ABSORBS LIGHT ENERGY BETWEEN 465 - 490 nm (BLUE) AND FLUORESCES AT 520 - 530 nm (GREEN - YELLOW).
C20H12O5NA
376.27 DALTONS
HOW MUCH SODIUM FLUORESCEIN DYE IS FREE AND HOW MUCH IS BOUND?
80% IS BOUND.
20% IS FREE. THIS IS THE PART THAT EMITS FLUORESCENCE.
WHAT IS PSEUDOFLUORESCENCE?
IT OCCURS WHEN NONFLUORESCENT LIGHT PASSES THROUGH THE ENTIRE FILTER SYSTEM - WHEN BLUE LIGHT REFLECTED FROM THE NONFLUORESCENT FUNDUS STRUCTURES PENETRATES THE GREEN-YELLOW FILTER.
HOW TO AVOID PSEUDOFLUORESCENCE?
CAREFULLY MATCHING THE EXCITATION (BLUE) AND BARRIER (GREEN-YELLOW) FILTERS SO THAT THE OVERLAP OF LIGHT BETWEEN THEM IS MINIMAL.
SODIUM FLUORESCEIN DOSE
500MG
- 10mL 5%
- 5mL 10%
- 3mL 25% (750 mg)
GREATER VOLUME - LONGER INJECTION TIME REQUIRED
SMALLER VOLUME - THE DYE MAY REMAIN IN THE VENOUS DEAD SPACE BETWEEN ARM AND HEART.
ORAL INTAKE
25 mg/kg
IMAGES TAKEN AFTER 40 - 60 min
ELIMINATION OF SODIUM FLUORESCEIN
LIVER AND KIDNEYS WITHIN 24 HOURS.
KIDNEY DISEASE AND DIALYSIS ARE NOT CONTRAINDICATIONS.
YELLOWISH SKIN AND URINE UP TO 24H.
SIDE EFFECTS AND COMPLICATIONS OF SODIUM FLUORESCEIN
- EXTRAVASATION / LOCAL TISSUE NECROSIS - RARE
- ARTERIAL INJECTION
- NAUSEA - MOST FREQUENT. 5% OF PATIENTS (30 SEC AFTER THE INJECTION).
- VOMITING. 0.3 - 0.4% OF PATIENTS (40 - 50 SEC AFTER THE BEGGINING OF THE EXAM -INITIAL IMAGES ARE ALREADY TAKEN. SLOW INJECTION TO AVOID IT).
- VASOVAGAL REACTION
- ALLERGIC REACTION (HIVES AND ITCHING 2 MIN - 15 MIN) / ANAPHYLAXIS
- NERVE PALSY
- NEUROLOGIC - SEIZURES
- TROMBOPHLEBITIS
- PYREXIA
- DEATH ( RISK 1 IN 220.000)
BREASTMILK VS FLUORESCEIN
FOUND UP TO 72 HOURS AFTER INJECTION.
IF NECESSARY, PUMP-AND-DUMP STRATEGY FOR 96 HOURS.
WHAT IS THE OPTOS SYSYTEM?
ULTRA-WIDEFIELD 200 DEGREES
ELLIPSOID MIRROR. CONFOCAL LASER (NOT A FLASH. NO TRUE COLLORS)
UP TO 82% OF THE RETINA WITH A SINGLE SCAN
WHAT IS THE SPECTRALIS ULTRA -WIDE SYSYTEM?
MODULE FOR THE SPECTRALIS. 102 DEGREES.
INTERCHANGEABLE LENSES
HIG-CONTRAST, UNDISTORTED IMAGES
IMPROVED VISUALIZATION OF SUPERIOR AND INFERIOR RETINA.
HOW TO INJECT FLUORESCEIN?
23 - 25 GAUGE NEEDLE. ANTECUBITAL VEIN // BACK OF THE HAND // SIDE OF THE WRIST.
COORDINATED WITH THE PHOTOGRAPHY PROCESS.
PREINJECTION PIC.
FIRST PIC WHEN INJECTION STARTS
SECOND PIC WHEN INJECTION ENDS
SOLWER INJECTION (4 -6 SECONDS) IS PREFERABLE.
INJECTION STARTS - TAKE A CONTROL PICTURE. THE TIMER STARTS COUNTING.
INITIAL-TRANSIT PHOTOGRAPHS AFTER THE BEGINNING OF THE INJECTION 8 SECONDS IN YOUNG AND 12 SECONDS IN OLDER PATIENTS.
THEN, RAPID SUCESSION EVERY 1.5 - 2 SECONDS.
20 - 30 SECONDS - PHOTOGRAPH OF THE MACULA AND OPTIC DISC OF THE FELLOW EYE
LATE PICS AT 5 - 10 MIN
INNER AND OUTER RETINA. HOW TO SPLIT?
INNER VASCULAR: ILM –> INNER NUCLEAR LAYER
- LARGER ARTERIES AND VEINS: NERVE FIBER LAYER
- SUPERFICIAL RETINAL CAPILLARIES: GANGLION CELL LAYER
- DEEP RETINAL CAPILLARIES: INNER NUCLEAR LAYER
OUTER AVASCULAR: OUTER PLEXIFORM LAYER/HENLE -> RODS AND CONES/RPE
- EXSUDATION IS FOUND IN OUTER PLEXIFORM AND INL.
- RPE IS FIRMLY ATTACHED TO THE BRUCH’S MEMBRANE.
- FLUORESCEIN PASSES FREELY FROM THE CHORIOCAPILLARIS AND BRUCH’S MEMBRANE, BUT NOT THROUGH THE RPE.
WHAT IS THE TRIANGULAR AMALRIC SYNDROME?
OCCLUSION OF THE SHORT POSTERIOR CILIARY ARTERIES OR THE LONG POSTERIOR CILIARY ARTERIES. IT CREATES WEDGE SHAPE INFARCTION AREAS NEAR THE MACULA. THE APEX IS DIRECTED TO THE FOVEA.
CAN BE ASSOCIATED WITH GIANT CELL ARTERITIS.
LPCA ALSO PERFUSES THE GREATER CIRCLE OF THE IRIS.
WHAT IS THE SIZE OF A CHORIOCAPILLARIS LOBULE?
1/4 - 1/2 DISC DIAMETER.
EACH IS FED BY A PRECAPILARY ARTEIOLE ORIGINATED FROM A SPCA.
HOW MANY VORTEX VEINS ARE THERE?
FOUR TO SEVEN
WHAT ARE THE LAYERS OF THE FOVEA?
FOUR LAYERS:
- ILM
- OPL / HENLE’S
- ONL
- RODS AND CONES
NORMAL HYPOFLUORESCENCE IN THE CENTER OF THE MACULA. WHY?
TALLER RPE CELLS (MORE COLUMNAR), GREATER CONCENTRATION OF MELANIN GRANULES; PRESENCE OF XANTHOPHYLL (IN HFL); CAPILLARY-FREE ZONE 400 - 500mm IN DIAMETER.