Angioid streaks

INTRODUCTION
 Angioid streaks were first described by Doyne
in 1889.
 They are also called Knapp’s striae as he first
coined the term in 1892 because of their
marked resemblance to blood vessels.
 However it was in 1917 that Kofler correctly
determined that they represented changes at
the level of Bruch’s membrane.

EPIDEMIOLOGY
 Angioid streaks have been documented in
early childhood but are not thought to be
present at birth.
 No known sex or race predilection exists.

PATHOGENESIS
 Angioid streaks represent breaks or dehiscences in
a thickened, calcified, and abnormally brittle
Bruch’s membrane.
 Whether the breaks occur spontaneously or are
caused only by trauma, even if minor, is not known.
 The initiating stimulation for the calcification and
degeneration of Bruch’s membrane in patients who
have angioid streaks is not yet known.

 The elastic lamina that occupies the midsegment of
Bruch’s membrane is primarily affected, which
results in disintegration and fraying of the elastic
fibers.
 Diffuse and extensive basophilic stains caused by
the deposition of calcium are commonly seen with
routine hematoxylin and eosin.
 The choriocapillaris and RPE are minimally affected
initially; however, with progression these
structures become secondarily degenerated..

 Eventually, neovascular vessels from the choroid
may penetrate through the breaks in Bruch’s
membrane.
 It results in subretinal hemorrhage, exudation,
and edema followed by the fibrovascular
deposition that is typical of a disciform scar.
 All cases of angioid streaks studied
histopathologically have shown identical changes
despite different underlying systemic diseases

Clinical appearance
 Angioid streaks appear as narrow, jagged lines
deep to the retina, almost always bilaterally.
 They can closely resemble blood vessels because
of their size, shape, color, and course.
Angioid streaks
typically radiate out in a
cruciate pattern from an
area of peripapillary
pigment alterations,
although they may
circumferentially ring
the peripapillary area as
well.

 Generally, they taper and fade a few millimeters away
from the optic disc; however, they have been reported
to extend farther anteriorly.
 Very rarely they occur in a random distribution
throughout the posterior pole.
 The number of streaks can be variable. Progression of
the streaks with time has been observed.

 The color of angioid streaks depends on the
background coloration of the fundus and the
degree of atrophy of the overlying retinal
pigment epithelium (RPE).
 In lightly colored fundi, angioid streaks are red,
reflecting the pigmentation of the underlying
choroid.
 In patients who have darker background
pigmentation, angioid streaks are usually a
medium to dark brown.

 The factors responsible for the
characteristic radiating configuration of
angioid streaks are not clear.
 It has been suggested that the pull of the
extraocular muscles creates stress forces
against the fixed point of the optic nerve,
which results in the characteristic pattern.

Other associated fundus
findings
Peau d’orange change
 Appear as diffuse mottling of
RPE, represent focal defects in
Bruch’s membrane and
choriocapillaries
 produce hypofluorescent areas on
fluorescein angiography (FA) and
speckled pattern in mid periphery
on ICG.
 They are usually seen in the
temporal midperiphery and may
be observed even before the
appearance of angioid streaks.

Salmon spots Peripheral punched out focal yellowish
atrophic RPE lesions.
Optic disc drusen - They are seen in around 10% of
patients.
They are produced due to attachment of calcium
containing macromolecules to elastic fibres of cribriform
plate which disrupt the axonal flow.
 Fresh haemorrhages.
 Paired red spots along streaks.
 Cracked egg shell appearance of
fundus- diffuse type of angioid
streaks.

Clinical course and
complications
 Patients with angioid streaks are
generally asymptomatic unless the lesions
extend towards the foveola or develop
complications .
 The increase in length and width of
streaks is considered an expected feature
of disease.

The various complications seen in such patients
are:
 Choroidal neovascularisation (CNV)
 Macular degeneration
 Traumatic membrane ruptures
 RPE tears

Choroidal neovascularisation
(CNV)
 It is the most common and serious complication
seen in 72-86% of patients.
 Commonly involves both the eyes but not
simultaneously, there is roughly an interval of 18
months.
 The risk of development of CNV increases with age
and it is seen that the wider and longer are the
streaks the higher the risk of CNV

 There is higher the risk of CNV specially if the
lesions are located in the distance less than one
optic disc diameter from the foveola.
 The standard outcome is poor if CNV in
macular region remains untreated as it will lead
to more extensive subfoveal scarring causing
severe vision deterioration.

Macular degeneration
 It is seen in 72% of these patients and is of two
types:
 Exudative
 It is more common and its occurrence is associated with:
 length of streak,
 the distance of streak from fovea or
 ‘cracked shell type of streak’
 however it does not occur in all the patients with streak
passing through fovea.
 Atrophic

Traumatic membrane ruptures
 Patients with angioid streaks develop breaks in
Bruch’s membrane even after relatively mild
injuries since their Bruch’s membrane is brittle.
 They are frequently followed by subretinal
haemorrhages which can be misinterpreted as
CNV.
 These haemorrhages appear next to angioid
streaks and sometimes disseminate to macular
area.
RPE tears
They have also been reported in angioid streaks.

Systemic associations
 Common systemic findings associated
with angioid streaks include
 pseudoxanthoma elasticum (34%),
 Paget’s disease (10%),
 hemoglobinopathies (6%).
 Upto 50% cases are, however, idiopathic.

Diagnosis
Fluorescein angiography (FA)
 First the initial photographs are taken with
filters on but before injecting the dye
 angioid streaks present the phenomenon of
autofluoresence.
 Also optic disc drusen associated with them also
show this phenomenon.
 Typically, angioid streaks show ‘window defect’
in FA due to RPE atrophy adjacent to them,
demonstrating early hyperfluorescence of the
streaks with late staining.

 Others have reported hypofluorescence of streaks
with hyperfluorescence of margins with late
staining.
 Leakage of fluorescein is evident when CNV is
present .
 On FA the angioid streaks will only become visible
when there are concomitant RPE alterations like
loss of pigment granules or ruptures in cell layer.

Indocyanine green angiography (ICG)
 It has been found to be superior to FA in
delineating angioid streaks and peau d’ orange
changes.
 Besides occult CNVM can be better detected on
ICG.
Optical Coherence Tomography (OCT)
 Detects the breaks in Bruch’s membrane and
helps in detecting and monitoring associated
abnormalities such as CNV.
Recently Near Infrared Reflectance imaging studies
using diode of 820 nm have shown very high
sensitivity in detection of angioid streaks.

Management
 Because even minor ocular trauma can cause
subretinal hemorrhages, patients should be
encouraged to use eye protection and avoid contact
sports.
 Therapy is possible and indicated only whenever a
CNV has developed.
 Prophylactic photocoagulation of angioid streaks
may stimulate CNV formation and is contraindicated.

Laser photocoagulation
 It has been widely used to treat well defined
juxtafoveal and extrafoveal CNV
 But high recurrence rates have been seen in CNV
associated with angioid streaks.
 Moreover laser induced scar progression has
also been reported resulting in deterioration of
visual acuity precluding its use in subfoveal
lesions.

Photodynamic therapy (PDT)
 Subfoveal lesions have been treated with PDT with
verteporfin.
 The short term benefits of PDT are limiting the
visual damage.
 But the long term results include:
 enlargement of the CNV lesion to a disciform scar
 associated visual loss,
 ruptures of already brittle Bruch’s membrane and
 damage to collateral choriocapillaries.

 It has also been seen that though PDT alone can
occlude CNV but it tends to cause transient
inflammatory response and increase in capillary
permeability along with enhanced expression of
vascular endothelial growth factor (VEGF)
shortly after the treatment.
 The VEGF upregulation typically peaks one week
post PDT resulting in recurrence of CNV and
limiting the efficacy of PDT alone.
 Combination therapy like PDT with intravitreal
Triamcinolone Acetonide (IVTA) or preferably
PDT with intravitreal Bevacizumab has also been
found to be efficacious not only in terms of
regression of CNVM and visual improvement but
also in reducing the number of treatments
required.

Anti VEGF agents
 Because of their unprecedented visual outcomes in
treatment of CNV due to age related macular
degeneration, anti-VEGF agents have been tried in
CNV associated with angioid streaks.
 In contrast to previous therapeutic regimens which
result in disciform scarring and irreversible loss of
RPE and overlying retina, intravitreal anti-VEGFs
have shown an improvement in visual acuity and
anatomic outcomes without causing a scar
formation especially in eyes that have not received
any treatment previously.

Other treatment modalities which have been
used in treatment of CNV in angioid streaks
are :
 transpupillary thermotherapy with
unfavourable outcome in terms of spreading
of lesions and
 macular translocation surgery whose role is
yet to be determined fully.

Take home Message
 Angioid streaks are visible irregular crack-like dehiscences in
Bruch’s membrane that are associated with atrophic
degeneration of the overlying RPE.
 They may be associated with pseudoxanthoma elasticum,
Paget’s disease, sickle-cell anemia, but also appear in patients
without any systemic disease.
 Patients with angioid streaks are generally asymptomatic, unless
the lesions extend towards the foveola or develop complications
such as traumatic Bruch’s membrane rupture or macular CNV.
 The visual prognosis in patients with CNV secondary to angioid
streaks if untreated is poor and most treatment modalities, until
recently, have failed to limit the devastating impact of CNV in
central vision.
 However, it is likely that treatment with anti-VEGF agents,
especially in treatment-naive eyes yields favourable results and
this has to be investigated in future studies

Angioid streaks

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