118
and more frequently in stage I), with early focal hyperflu-
orescence (corresponding to the angiomatous formation),
leakage and staining, in the intermediate and late stages.
Angiographic appearance in stages II and III is often that
of minimally classic or occult membranes. However, it is
very difficult to distinguish between intraretinal neovas-
cularization and choroidal neovascularization or vascular-
ized retinal pigment epithelial (RPE) detachment by FA
(Fig. 1 and 3).
Hot spots normally appear in areas with no window effect,
being observed before filling of the RPE detachment with
fluorescein. Stereo FA allows viewing of leakage in the
deep retina or the subretinal space
(8,19)
. The initial stages
in the filling of deep vascular lesions and afferent arteri-
oles are often only visible in videoangiography, since fill-
ing occurs simultaneously. Angiomatous lesions may con-
tinue to fill even after venous drainage has started
(17,19)
.
Indocyanine green angiography (ICG)
In ICG, a hyperfluorescent focus is visible, which may be
observed in all 3 stages, fading only in later stages (Fig. 2).
Late staining or intraretinal oedema, which are typical
occurrences in RAP, may also be observed. Intraretinal
exudates contain fibrin
(18)
, which may be stained with
indocyanine but not with fluorescein. A hypofluorescent
area corresponding to serous RPE detachment may also
be observed. With confocal high-speed ICG, early frames
allow the establishment of a relationship between RAP
and retinal circulation, although without denying the
existence of chorioretinal anastomosis
(7,10)
. High-speed
videoangiography also allows identification of retino-
retinal anastomoses, chorioretinal anastomoses, feeding
arterioles and draining venules (Fig. 2).
Stereo ICG with scanning laser ophthalmoscopy (SLO)
shows that RAP consists of a neovascular complex with
two components: one is the hot spot (which fills one to
three seconds after filling of choroidal arteries, with mod-
erate late leakage); the other consisting of one or more
retinal vessels (arteries and particularly veins (70% vs.
30%) (plunging into or emerging from the hot spot)
(19)
.
In stage III, vascularized pigment epithelial detachment
(PED) may be observed in ICG. The serous component
of PED is hypofluorescent; the vascular component
remains hyperfluorescent.
3.3 Optical coherence tomography (OCT)
OCT imaging is an important tool in the diagnosis of
RAP. Stage I and II lesions are often associated with a
located below the RPE – type 1 choroidal neovascularization
– and no clinical signs of chorioretinal anastomosis. ICG
would be necessary to identify type 1 neovascularization.
ii) Early clinical signs – Anastomosis between dilated cap-
illaries of the deep retina and the choroidal neovascular
complex is associated with small intraretinal haemorrhages,
which would constitute the first clinical sign of chorioreti-
nal anastomosis. This stage may occur weeks or months
before stage 3, where subretinal choroidal neovasculariza-
tion is already observed.
iii) Proliferation of choroidal neovascularization over the
RPE – subretinal neovascularization – type 2 CNV.
iiii) Appearance of serous PED caused by activation of
newly formed subepithelial vessels.
iiiii) Mixed neovascularization – piggyback-type neovascu-
larization, with two levels – type 1 and type 2 with cicatricial
disciform lesion, making chorioretinal anastomosis visible.
Stage 3 in the Gass classification corresponds to stage I in
the Yannuzzi classification, with stages 4 and 5 in the Gass
classification corresponding to stages II and III, respectively.
Currently, the Yannuzzi classification is the most widely
used.
3. Diagnosis of RAP
3.1 Clinical observation
The presence of small central macular haemorrhages, some-
times punctiform, associated with oedema in an eye with
soft drusen, is highly suggestive of RAP in its initial stages
(Fig 1).
The following lesions suggest RAP in AMD
(8-17)
:
i) Small multiple haemorrhages, pre, intra or subretinal,
normally not observed in macular neurosensory detach-
ments with choroidal neovascularization.
ii) Tortuous, dilated retinal vessels, sometimes showing ret-
ino-retinal anastomoses (Fig. 2).
iii) Telangiectasias.
iv) Microaneurysms.
v) Sudden disappearance of a retinal vessel that appears to
have moved deeper.
vi) Hard exudates around the retinal lesion (Fig. 1,3,4).
3.2 Angiography
Fluorescein angiography (FA)
Angiographic appearance varies with the stage of the dis-
ease. It may be identical to classic neovascularization (rarely
