Retinal artery occlusion is an ophthalmic emergency which requires urgent management. Its a vision threatening condition which requires prompt diagnosis.
4. INTRODUCTION
Retinal arterial obstructions are divided anatomically
depending on the precise site of obstruction:
Central - occurs when the blockage is within the optic
nerve substance itself and site of obstruction is not
visible on ophthalmoscopy.
Branch - occurs when the site of blockage is distal to the
lamina cribrosa of the optic nerve
More proximal obstructions usually cause a more
chronic form of visual problem − the ocular ischemic
syndrome
5. Majority of retinal arterial obstructions are either
thrombotic or embolic in nature.
Branch retinal artery obstruction is far more likely to be
embolic than is a central retinal artery obstruction
Retinal artery obstructions selectively affect the inner
retina only
6. BLOOD SUPPLY
The outer retina is supplied by the ciliary arteries via the
choriocapillaris and the inner retina by the central
retinal artery (CRA).
The ophthalmic artery gives rise to both the CRA – its
first branch – and the ciliary arteries.
Atherosclerosis-related embolism and thrombosis are
thought to be responsible for the majority of cases of
retinal artery occlusion.
7.
8. The origin of emboli is most commonly an
atheromatous carotid plaque; the ophthalmic artery is
the first branch of the internal carotid artery, so embolic
material has an easy route to the eye.
9. Inflammation in or around the vessel wall :
Giant cell arteritis – GCA
Systemic lupus erythematosus
Wegener granulomatosis
Polyarteritis nodosa
Vasospasm (e.g. migraine)
Systemic hypotension
contribute in a minority.
10. CENTRAL RETINAL ARTERY OBSTRUCTION.
Rare event − it has been estimated to account for about
1 in 10000 outpatient visits to the ophthalmologist.
Men are affected more commonly than women in the
ratio 2:1.
The mean age at onset is about 60years
Bilateral involvement occurs in 1–2% of cases
11. When both eyes are simultaneously affected by retinal
artery obstruction, the differential diagnosis should
include :
Cardiac valvular disease
Giant cell arteritis
Other vascular inflammations.
12. ETIOLOGY
Thrombosis- at level of lamina cribrosa
Atherosclerosis
Congenital abnormality of central retinal artery
Coagulopathies
Embolism (20-25%) – Origin from atheromatous carotid
plaque.
Cholesterol (Hollenhorst plaques)
Platelet-fibrin
Calcific
14. Thrombophilic disorders (In one-third of young patients)
Hyperhomocystinemia
Anti-phospholipid antibody syndrome
Sickling hemoglobinopathies
Susac syndrome ( Retino-cochleo-cerebral syndrome)
Protein C& S deficiency
Anti-thrombin III deficiency
15. Rare causes
Radiation retinopathy
Emboli secondary to depot medications around eyes
Optic nerve drusens
Peripapillary arterial loops
Medical examination and manipulation Eg: Carotid
angiography, angioplasty , chiropractic neck
manipulation
16. AMAUROSIS FUGAX
Transient monocular loss of vision
Amaurosis fugax study group divides cause into five
categories:
Embolic
Ocular
Neurologic
Hemodynamic
Idiopathic
Recovery is in the same pattern as lost.
17. CLINICAL FEATURES
The hallmark symptom of acute central retinal artery
obstruction is abrupt, painless loss of vision.
Pain is unusual and suggests associated ocular ischemic
syndrome (OIS).
Amaurosis fugax precedes visual loss in about 10% of
patients.
In cases associated with arterial spasm, a relapsing and
remitting course of visual loss precedes central retinal
artery obstruction.
18. Visual acuity of 20/800 (6/240) or worse.
No light perception vision is uncommon except in case
of ophthalmic artery obstruction or temporal arteritis.
Patent cilioretinal artery - perfuses the fovea, normal
central acuity may be present.
Afferent pupillary defect on the affected side.
19. Anterior segment examination is normal
(Except in concurrent OIS with neovascularization of the
iris)
20. FUNDUS
Within the first few minutes to hours after the
obstruction, the fundus may appear relatively normal.
Decreased blood flow results in ischemic whitening of
the retina in the territory of the obstructed artery.
Most pronounced in the posterior pole (where the
nerve fiber layer of the retina is thickest).
Acutely arteries appear thin and attenuated.
21. Retinal whitening is very subtle and the retinal vessels
appear normal.
Fluorescein angiography reveals abnormal arterial filling
with a leading edge of dye that confirms central retinal
artery obstruction.
The same eye 24 hours later- intense retinal whitening
with a cherry-red spot is present.
22. In severe blockages, both veins and arteries may
manifest “box-carring” or segmentation of the blood
flow.
23. Cherry-red spot of the macula is typical ( arises in
because of thin nerve fiber layer).
Transmission of the normal choroidal appearance is not
diminished, which contrasts distinctly with the
surrounding area of intense retinal whitening that
blocks transmission of the normal choroidal coloration.
26. Splinter retinal hemorrhages on the disc are common.
If pallid swelling is present, temporal arteritis must be
ruled out.
A patent cilioretinal artery results in a small area of
retina that appears normal .
27. Prominent cherry-red spot with cilioretinal artery
sparing in the papillomacular bundle.
28. By 6 weeks after the acute event:
Retinal whitening resolves
Optic disc develops pallor
Arterial collaterals forms on the optic disc
No foveolar light reflex apparent
Fine changes in the retinal pigment epithelium may
be visible.
29. Secondary ocular neovascularization occuar 8 weeks
after the obstruction
Iris neovascularization occurs in about 18% of patients
with many developing to neovascular glaucoma.
Neovascularization of the optic disc occurs after about
2% of central retinal artery obstruction
Vitreous hemorrhage may also occur.
30. Central retinal artery
obstruction caused by a
platelet-fibrin embolus.
After 3 months,
extensive
neovascularization of
the disc is present.
31. DIAGNOSIS AND ANCILLARY TESTING
Diffuse ischemic retinal whitening is present in the
setting of abrupt, painless visual loss.
Fluorescein angiography
Optical coherence tomography
Electroretinogram
Visual field
32. FLUORESCEIN ANGIOGRAPHY
Delayed arm-to-retina time with a leading edge of dye
visible in the retinal arteries is typical
Arteriovenous transit is delayed :time elapsed from the
appearance of dye within the arteries of the temporal
vascular arcade until the corresponding veins are
completely filled; normal is less than or equal to 11
seconds
Late staining of the disc is common.
33. Severe left central retinal artery obstruction with segmentation of
the blood column in the retinal vessels (arrows).
Fluorescein angiogram at 52 seconds after injection reveals poor
filling. The leading edge of dye (arrow) within the inferior retinal
arterial system is distinctly abnormal and indicates
hypoperfusion.
At nearly 6 minutes after injection, the retinal vessels are still
poorly filled. The hypofluorescent focus (arrow) on the optic disc
corresponds to staining of an embolus within the central retinal
artery
34. Complete lack of filling of the retinal arteries is unusual
and occurs in less than 2% of cases.
The choroidal vascular bed in eyes usually fills normally,
delays of five seconds or greater seen in about 10% of
cases
A marked prolongation of choroidal filling in the
presence of a cherry-red spot should arouse suspicion
of an ophthalmic artery obstruction or a concomitant
carotid artery obstruction
35. The retinal circulation has propensity to re-establish the
circulation following an acute central retinal artery
obstruction.
Arterial narrowing and visual loss may persist, but the
fluorescein angiogram can revert to normal at varying
times after the insult.
36. OPTICAL COHERENCE TOMOGRAPHY
Macular optical coherence tomography (OCT) in the
acute phase shows inner retinal thickening with
shadowing of the outer retina that can be mistaken for
subretinal fluid.
When the retinal whitening resolves, OCT reveals
severe inner retinal thinning.
OCT angiography of prior central retinal artery
obstruction demonstrates decreased retinal vascularity
and attenuation of vessels in the macula
37. Optical Coherence
Tomography
Angiography and
Corresponding Optical
Coherence
Tomography Structural
B-Scan From an Eye
With a Prior Central
Retinal Artery
Obstruction.
Paucity of small retinal
vessels in the macula
and the attenuation of
the large retinal
vessels. Structural B-
scan shows loss of
inner retinal tissue.
38. ELECTRORETINOGRAPHY
Diminution in the amplitude of the b-wave
(corresponding to the function of the Muller and/or
bipolar cells) secondary to inner layer retinal ischemia.
The a-wave, which corresponds to photoreceptor
function, is generally unaffected.
In some eyes the study is normal in the presence of
decreased vision, possibly because of the re-
establishment of retinal blood flow
39. Electroretinograms of a normal right eye (upper
tracing) and a left eye (lower tracing) affected by a
CRAO.
The “b” wave is diminished in the lower tracing of the
CRAO eye, but the “a” wave is normal.
40. VISUAL FIELD
Demonstrate a remaining temporal island of vision,
presumably because the choroid nourished the
corresponding nasal retina.
In the presence of a patent cilioretinal artery, small
areas of central vision are preserved.
Depending upon the degree and the extent of the
obstruction, varied portions of the peripheral field may
remain.
41. SYSTEMIC ASSOCIATIONS
About 50%–60% of patients have concurrent systemic
arterial hypertension, and diabetes is present in 25%.
Systemic evaluation reveals no definite cause for the
obstruction in over 50% of affected patients.
The Retinal Emboli of Cardiac Origin Study Group, a
multicenter study, reported on the cardiac findings
associated with acute retinal arterial occlusion
45. DIFFRENTIAL DIAGNOSIS
Single or multiple branch retinal artery obstruction
Cilioretinal artery obstruction
Severe commotio retinas
Necrotizing herpetic retinitis
46. COURSE AND OUTCOME
Most central retinal artery obstructions result in severe,
permanent loss of vision.
About one-third of patients experience some
improvement in final vision in terms of presentation
acuity either with or without conventional treatment.
Three or more Snellen lines of improved visual acuity
occur in only about 10% of untreated patients.
Spontaneous recovery may be more common in young
children.
47. BRANCHED RETINAL ARTERY OCCLUSION
Rare event, less common than central retinal artery
obstruction overall.
Exception - comparative incidence with young patients,
in whom branch retinal artery obstruction is the more
common type of retinal artery obstruction.
Men are more affected than women by a 2 : 1 ratio,
reflects the higher incidence of vasculopathic disease in
men.
Young patients (less than 50 years of age), women and
men are affected equally.
48. Mean age of affected patients is 60 years (Range -
second decade to tenth).
The right eye (60%) is affected more commonly than the
left (40%), which reflects the greater possibility of
cardiac or aortic emboli traveling to the right carotid
artery.
Branch retinal artery obstruction strikes the temporal
retinal circulation far more frequently than the nasal.
49. Over two-thirds of branch retinal artery obstructions are
secondary to emboli to the retinal circulation.
In most cases, the emboli are clearly visible in the
arterial tree.
Emboli to the retinal circulation may originate at any
point in the proximal circulation from the heart to the
ophthalmic artery.
50. Risk factors reflect the vasculopathic mechanisms that
produce disease within the cardiovascular system:
Predisposing family history
Hypertension
Elevated lipid levels
Cigarette smoking
Diabetes mellitus
51. Three main types of retinal emboli have been identified:
• Cholesterol (Hollenhorst plaque)
• Platelet-fibrin
• Calcific
52. Cholesterol emboli typically emanate from
atheromatous plaques of the ipsilateral carotid artery
system, aorta or heart valves may also be a source.
Yellow–orange in color, refractile, and globular or
rectangular in shape.
They are small and can be seen intravascularly without
blockage of blood flow.
53. Cholesterol embolus (arrow) in the fundus of an
asymptomatic woman.
Embolus is present at the bifurcation, since it is trapped
as the lumen of the artery narrows
54. Platelet-fibrin emboli are long, smooth, white-colored,
intra-arterial plugs that may be mobile or break up over
time.
Usually they are associated with carotid or cardiac
thromboses.
55. Calcific emboli are solid, white, nonrefractile plugs
associated with calcification of heart valves or the aorta.
56. Less commonly seen embolic types :
Tumor cells from atrial myxoma or a systemic
metastasis
Septic emboli associated with septicemia or
endocarditis
Fat emboli associated with large bone fractures
Emboli dislodged during angioplasty or angiography
Depot drug preparations from intra-arterial
injections around the eye or face
57. Rarely, local ocular conditions produce branch retinal
artery obstruction including:
Inflammatory diseases such as toxoplasmosis
Acute retinal necrosis
Mechanical compression from anterior ischemic optic
neuropathy
Structural entities such as optic disc drusen or
prepapillary arterial loops
58. Systemic hematological or clotting problems -
isolated branch retinal artery obstruction or multiple
recurrent branch retinal artery obstruction
Systemic vasculitides, such as polyarteritis nodosa
Local vasculitis associated with varicella infection
Oral contraceptive use and cigarette smoking - in
young, otherwise healthy women
59. CLINICAL FEATURES
Symptoms.
Sudden and profound painless altitudinal or sectoral
visual field loss.
Can sometimes go unnoticed, particularly if central
vision is spared.
VA
Variable
In patients where central vision is severely
compromised, the prognosis is commonly poor
unless the obstruction is relieved within a few hours .
60. RAPD is often present.
Amaurosis fugax occurs in about one-fourth of patients
prior to frank obstruction, especially case of carotid
disease.
Bilateral simultaneous branch retinal artery obstruction,
which can mimic homonymous field defects can occur
rarely.
61. Fundus signs may be subtle :
Attenuation of arteries and veins with sludging and
segmentation of the blood column (‘cattle trucking/
boxcarring’).
Cloudy white oedematous (ground glass) retina
corresponding to the area of ischaemia.
One or more occluding emboli may be seen,
especially at bifurcation points.
The affected artery is likely to remain attenuated.
Recanalization may leave absent ophthalmoscopic
signs.
62. A syndrome of multiple, recurrent, bilateral branch
retinal artery obstruction in young, otherwise healthy
patients has been reported.
A few of the patients also manifest vestibuloauditory
Susac’s syndrome, a rare disorder that manifests as a
microangiopathy of the central nervous system.
63. Inferotemporal occlusion – embolus visible over the
disc
Superior branch retinal artery occlusion due to an
embolus at the disc
64. FA shows lack of arterial filling of the involved artery and
hypofluorescence of the involved segment due to
blockage of background fluorescence by retinal swelling
66. In the chronic phase, when the retinal whitening has
diminished, a loss of the nerve fiber layer in the affected
area is apparent.
Arteriolar collaterals on the optic disc or at the site of
obstruction may develop
67. ANCILLARY TESTING
Visual field testing confirms the defect, which rarely
recovers.
FA shows delay in arterial filling and hypofluorescence of
the involved segment due to blockage of background
fluorescence by retinal swelling
OCTA demonstrates vascular features that correlate with
FA and provide improved visualization of the
microvasculature compared to FA.
68. OCT initially reveals thickening and hyperreflectivity
consistent with intracellular edema of the inner retina in
the territory of the obstructed artery.
Over time, corresponding inner retina will be severely
thinned.
69. Review in 3 months is warranted to review the
appearance of the fundus and visual fields
Provide advice on prognosis and confirm that systemic
management has been carried out appropriately.
71. CILIORETINAL ARTERY OCLUSION
A cilioretinal artery is present in 15–50% of eyes
Its main importance is that when present it may
facilitate preservation of central vision following central
retinal artery occlusion, provided the fovea is supplied.
72. Isolated cilioretinal artery occlusion and FA of the eye
shows hypofluorescence in the affected area due to
reduced filling and masking by retinal oedema
Isolated- rare; occur in young patients with an
associated systemic vasculitis.
Isolated; (B) FA of the eye in (A) shows
hypofluorescence in the affected area due to
reduced filling and masking by retinal oedema;
73. Isolated cilioretinal artery obstruction
Fluorescein angiogram demonstrates poor filling of the
obstructed cilioretinal artery and retinal capillary
nonperfusion within the area of distribution of the vessel.
74. Combined with CRVO- occlusion is transient and the
prognosis is better than in isolated cilioretinal artery
occlusion.
75. Combined with anterior ischaemic optic neuropathy
typically affects patients with GCA and carries a very
poor prognosis.
76. OPHTHALMIC ARTERY OCCLUSION
Acute simultaneous obstruction of both the retinal and
choroidal circulations is referred to as an ophthalmic
artery obstruction.
Cases of ophthalmic artery obstruction usually have
associated local orbital or systemic diseases including:
Orbital mucormycosis
Orbital trauma
Retrobulbar anesthesia
Depot corticosteroid injection
Atrial myxoma
Carotid artery disease.
77. Ophthalmic artery obstructions can be differentiated
clinically from central retinal artery obstruction by the
following features:
• Severe visual loss—bare or no light perception.
• Intense ischemic retinal whitening that extends
beyond the macular area.
• Little to no cherry-red spot.
• Marked choroidal perfusion defects on fluorescein
angiography.
• Nonrecordable electroretinogram.
• Late retinal pigment epithelium alterations
78. COMBINED ARTERY AND VEIN OBSTRUCTIONS
Central retinal artery obstruction combined with
simultaneous central retinal vein obstruction rarely
occurs.
Patients typically present with acute, severe loss of
vision.
Examination shows a cherry-red spot combined with
features of a central retinal vein obstruction, which
include dilated, tortuous veins that have retinal
hemorrhages in all four quadrants
79.
80. Associated systemic or local disease is the rule—
Collagen vascular disorders
Leukemia
Orbital trauma
Retrobulbar injections
Mucormycosis
The visual prognosis is generally poor and the risk of
neovascularization of the iris is about 75%.
81. SYSTEMIC EVALUATION
Urgent specialist vascular evaluation, typically within 24
hours, is the standard of care following a retinal arterial
event, including amaurosis fugax
Risk of a stroke is relatively high in the first few days
after a transient ischaemic attack (TIA).
The detection of atrial fibrillation is of particular
importance as admission for anticoagulation may be
indicated.
82. ALL PATIENTS
Smoking
Symptoms of GCA (1–2% of central retinal artery
occlusion – CRAO) :
Headache, jaw claudication, scalp tenderness, limb
girdle pain, weight loss and existing polymyalgia
rheumatica
Extremely unlikely under 55–60 years.
Constitutes an ophthalmic emergency
83. Pulse - detect arrhythmia, particularly atrial fibrillation.
Blood pressure.
Cardiac auscultation for a murmur.
Carotid auscultation is of limited value as the absence
of a bruit does not exclude significant stenosis.
ECG to detect arrhythmia and other cardiac disease.
ESR and CRP to identify possible GCA.
84. Other blood tests include :
CBC (platelets may be raised in GCA)
Glucose
Lipids
Urea and electrolytes
85. Carotid duplex scanning is a non-invasive screening test
involving a combination of high-resolution real-time
ultrasonography with Doppler flow analysis. If significant
stenosis is present, surgical management may be
considered
86. SELECTED PATIENTS
Considered on a targeted basis in some patients,
particularly if younger and with no known
cardiovascular risk factors, or there is an atypical clinical
picture.
87. Further carotid imaging
Cranial magnetic resonance imaging (MRI) or computed
tomography (CT) may be indicated to rule out
intracranial or orbital pathology.
Echocardiography- Usually performed in young patients
or if there is a specific indication such as a history of
rheumatic fever, known cardiac valvular disease, or
intravenous drug use.
Chest X-ray. Sarcoidosis, tuberculosis, left ventricular
hypertrophy in hypertension.
24-hour ECG to exclude intermittent arrhythmia.
88. Additional blood tests :
Fasting plasma homocysteine level to exclude
hyperhomocysteinaemia.
‘Thrombophilia screen’ - refers to heritable
thrombophilias, which have predominantly been
implicated in venous rather than arterial thromboses.
Plasma protein electrophoresis to detect
dysproteinaemias such as multiple myeloma.
Thyroid function tests, especially if atrial fibrillation is
present; may be associated with dyslipidaemia.
89. Autoantibodies: Rheumatoid factor, anticardiolipin
antibody, antinuclear antibody, anti-double stranded
DNA antibodies, principally looking for vasculitis in
younger patients.
Syphilis serology.
Blood cultures.
90.
91. TREATMENT
Retinal artery occlusion is an emergency because it
causes irreversible visual loss unless the retinal
circulation is re-established prior to the development of
retinal infarction.
Theoretically, timely dislodgement of thrombus or
emboli may ameliorate subsequent visual loss
Treatments may be tried in patients with occlusions of
less than 24–48 hours’ duration at presentation, though
evidence of benefit is limited.
92. The number of measures tried and the intensity of
treatment should be tailored to the individual
More aggressive if lower duration of occlusion, good
general health, monocularity
More aggressive systemic treatment may be avoided
in the frail elderly
Lack of evidence for clear benefit and the risks, should
be discussed before use
93. Adoption of a supine posture:
Might improve ocular perfusion and should always be
implemented
94. Ocular massage :
Using a three-mirror contact lens (allows direct artery
visualization).
Aim is to mechanically collapse the arterial lumen
and cause prompt changes in arterial flow, improving
perfusion and potentially dislodging an embolus or
thrombus.
One described method consists of positive pressure
for 10–15 seconds followed by release, continued for
3–5 minutes.
Self-massage through closed eyelids can be
continued by the patient.
95. Breathing a high oxygen (95%) and carbon dioxide (5%)
mixture, ‘carbogen’, has been advocated for a possible
dual effect of retarding ischaemia and vasodilatation.
‘Rebreathing’ into a paper bag in order to elevate blood
carbon dioxide and respiratory acidosis has been
advocated, as this may promote vasodilatation
96. Anterior chamber paracentesis
Using 27-gauge needle to withdraw 0.1–0.2 ml of
aqueous is controversial but has been advocated by
some authorities.
Povidone-iodine 5% and topical antibiotic are instilled
a few minutes prior to the procedure, with a short
course of antibiotic afterwards.
It may be prudent for ocular massage to be avoided
following paracentesis.
97. Transluminal Nd:YAG laser embolysis or embolectomy :
BRAO or CRAO in which an occluding embolus is
visible
Shots of 0.5–1.0 mJ or higher are applied directly to
the embolus using a fundus contact lens.
Embolectomy has been said to occur if the embolus is
ejected into the vitreous via a hole in the arteriole.
The number of shots described in reports is
extremely variable.
The main complication is vitreous haemorrhage
98. Topical apraclonidine 1%, timolol 0.5% and intravenous
acetazolamide 500 mg to achieve a more sustained
lowering of intraocular pressure.
Sublingual isosorbide dinitrate to induce vasodilatation
Hyperosmotic agents
Mannitol or glycerol have been used for their
possibly more rapid IOP-lowering effect as well as
increased intravascular volume
99. Thrombolysis:
Extrapolating from successful treatment of stroke
and myocardial infarction, various strategies have
been used to deliver thrombolytic agents to the
ophthalmic artery, including local arterial (internal
carotid and ophthalmic) and intravenous infusion.
A recent large trial of local intra-arterial fibrinolysis
with recombinant tissue plasminogen activator (rtPA)
showed no benefit over conservative treatment that
included isovolaemic haemodilution
Nearly 40% adverse reaction rate in the rtPA group.
100. OPD MANGEMENT
Aim should be to decrease IOP as it cause :
Dislodgement of embolus
Produce retinal dilatation and increase perfusion
101. Ocular massage is of utmost important especially with
goldmann contact lens – done till re-establishment of
continuous laminar flow and increase in width of blood
column and disappearance of fragmented flow.
IOP lowering agents
Carbogen inhalation
AC paracentesis