imaging for retinal pathology

1. PRESENTER: Dr NIKITA
JAISWAL
2nd RESIDENT

2. F: FUNDUS – corresponds to retina
 F: FLUORESCEIN – corresponds to dye used
 A: ANGIOGRAPHY – study of the blood vessels

3.  BACKGROUND
 PHASES
 INDICATIONS
 CONTRADICTIONS

4.  FFA: This is based on the principle of studying the
vasculature of retina with the help of injecting dye
and then studying the contrast report after
photographing it.
The dye used is the fluorescein solution.

5. Fundus angiography---fluorescence--luminiscence
When light energy is absorbed into a luminescent
material, free electrons are elevated into higher energy
states. This energy is then re-emitted by spontaneous decay of
the electrons into their lower energy states. When this decay
occurs in the visible spectrum, it is called luminescence.
Fluorescence is luminescence that is
maintained only by continuous
excitation

6.  INTRODUCTION:An orange-red crystalline hydrocarbon,has a low
molecular weight & readily diffuses through most of the body fluids
and through the choriocapillaris.
 AVALABILITY:
 500 mg fluorescein are available in vials
of 10 mL of 5% fluorescein or 5 mL of 10% fluorescein.
Also 3 mL of 25% fluorescein solution (750 mg)
 ELIMINATION:This is eliminated through liver & kidneys

7.  Fundus camera and auxiliary equipment
 Matched fluorescein filters (barrier and exciter)
 23-gauge scalp vein needle
 5 mL syringe
 5 mL of l0% fluorescein solution
 2 -inch needle to draw the dye
 Armrest for fluorescein injection
 Tourniquet
 Alcohol swabs
 Bandage
 Standard emergency equipment

8.  Exposed to light to a particular wavelength---fluorescent substance absorbs
energy & electrons are raised to a higher energy—now this substance
emits light of longer wavelength.
 When excited by blue light(465-490nm)
 It emits yellow green light (520—530nm).

9.  Pupils: dilated
 Film: white& black on which retnal & choroidal
vasculature is recorded.
 Camera:electronic flash of a xenon light source.
 Excitor filter: permits transfer of only blue light into the
eye
 Barrier filter: it filters & eliminates the unwanted blue
light

16. Fundamentals
PRINCIPLES

17.  Anatomy & physiology of eye.
 The retinal circulation
 The choroidal circulation
 The blood retinal barrier
 Passage of the dye.

18. Retinal circulation: Choroidal circulation:
Blood vessels– from CRA—
The main vessels are found in the
nerve fibre layer.
Fine capillaries are found in inner
nuclear layer & outer plexiform
layer.
There are no capillaries in about
400-500 microns in diameter
around the fovea.
Endothelial cells in these capilaries
have tight junctions which prevent
its passage .
30% of eyes there is a cilioretinal
artery.
Highly vascular tissue.
Chorocapillaries consists of large
,thin walled capillaries with
fenestrations which allow the
passage which allows some
plasma proteins.
choroid is supplied by
segmentally supplied by both the
large & small capillaries.

19. Outer blood barrier
 Retina—RPE---choroid.
 Hexagonal cells are arranged in a
monolayer –zona occludentes
which do not allow the diffusion
of smaller molecules
Transport of water & waste occurs
in the other direction.

20. The endothelial cells lines the capillaries
of the retina & thus forms the inner
retinal blood barrier
All fluid & metabolic transport takes
place by active process through the
endothelial cells.
 Inner blood barrier

21.  Dye passes through the choroidal circulation first &
then through the retinal circulation.
 It does not crosses through the bruch’s membrane

22.  Time it appears:-10-15 secs after injection.
 Factors influences it-speed of injection
tight clothing around the arm
cardiovascular status.
 Sequential photography: Dye appearance in choroidal
then followed by retina after
1-2 secs only.

23.  Choroidal phase(pre-arterial phase)
 Arterial phase
 Arteriovenous phase(capillary)
 Early venous phse
 Mid-venous phase
 Late fluorescence

24.  Occurs after 9-15 secs after
injection
 Patchy lobular due to leakage of
free fluorecein from fenestration
choriocapillaries.

25.  Starts about a second
after the choroidal
fluorescence .
 Retinal arteriolar filling
is seen.

26.  Shows complete filling of
arteries & capillaries with
early laminar flow in the
veins.
Laminar flow
Seen
Leaving an axial
hypofluorescnt

27.  Shows progress to
complete filling

28.  Reduced arterial
fluorescence.

29.  Shows recirculation ,
dilution & elimination of
the dye.
 Fluorescein disappears
from retinal vasculature
after 10 minutes.

31. Hyperfluorescence : Is abnormally excessive
fluorescence
Hypofluorescence: Reduction or absence of
fluorescence.

32. hyperfluorescence
autofluorescence
Staining/pooling
/leakage
pseudofluoresence
Window defect.
hypofluorescence
blocking/masking
Filling defects

33.  Autofluorescence: It occurs in absence of fluorescein.
ex: exposed optic nerve drusen which is inherently
fluorescent.

34. It is due to reflected light from the eye
passing through the camera filters.
Scar tissue
Foreign body
Myelinated
nerve fibre

35.  LEAKAGE: This is a misuse word & it implies
permeability of “BRB” which can be focal & diffuse.

38.  Pooling: Dye collection in anatomical spaces leads to
characteristics pattern.
 Ex: cystoid macular oedema
central serous retinopathy

41.  Staining: often confused with the leakage.
It means that the stain is taken up by the
tissues even after the stain has left the ocular circulation.

43.  Transmission/window defect:-reduction of
pigmentation without any breach in the
physiological barrier between the neuroretina & the
choroidal vasculature

44. Rpe atrophy allows
choroidal
fluorescence
through with
choroidal flush .
Does not change
size or shape with
time.
Fades with
choroidal
fluorescence.

47.  BLOCKAGE /MASKING: OPTICALLY OPAQUE
STRUCTURE IN THE PATH OF LIGHT BETWEEN
FUNDUS & CAMERA.

53. Managements

54.  Extravasation and local-tissue necrosis13
 Inadvertent arterial injection
 Nausea11–13
 Vomiting
 Vasovagal reaction (circulatory shock, myocardial infarction)12
 Allergic reaction, anaphylaxis (hives and itching, respiratory
 problems, laryngeal edema, bronchospasm)
 Nerve palsy
 Neurologic problems (tonic-clonic seizures)
 Thrombophlebitis
 Pyrexia
 Death

55.  Extravasation: for this local ice pack should be given at the area of
extravasation.
 If the extravasation occurs earlier it’s the physician who decides
whether to continue the procedure or not.
 Prevention: to use a scalp vein needle which is flexible & not the large
needle which is directly attached to the syringe.
 NAUSEA: It starts within 20-30 seconds & last for 2-3 minutes & then
disappears slowly.
 VOMITING:It starts within 40-50 seconds post injection.
 HIVES & ITCHING: It starts after 2-15 mins of injection.

56.  No contraindication to cardiac disease, pace
makers,cardiac arrhythmias.
 No teratogenicity (but avoided in 1st trimester of
pregnancy).

57.  An oxygen cylinder
 A sphygmomanometer
 A stethoscope
 An airway support system.