non-ischemic central retinal vein occlusion
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Central Retinal Vein Occlusion (CRVO)
Impending Central Retinal Vein Occlusion
Impending (partial) CRVO is a relatively poorly-defined condition which may resolve or progress
to complete obstruction.
Presentation:
Mild blurring of vision characteristically worse on waking and improves during the day.
Signs:
Mild venous dilatation and tortuosity with a few widely scattered flame-shaped haemorrhages.
Fluorescein Angiography (FA):
It shows increased retinal circulation time.
Optical coherence tomography (OCT):
It may facilitate a degree of objective monitoring of the macular course, if cystoid macular
edema (CME) is present.
Treatment:
It is aimed at preventing progression to complete occlusion by correcting any predisposing
systemic conditions, avoiding dehydration, and lowering intraocular pressure (e.g. systemic
carbonic anhydrase inhibitors) to improve perfusion. Antiplatelet agents may be of benefit, and
in some circumstances such as monocularity in an otherwise healthy patient it may be
appropriate to consider other options such as anticoagulants, fibrinolytics or haemodilution.
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Central Retinal Vein Occlusion (CRVO)
Non-ischemic Central Retinal Vein Occlusion
Non-ischemic CRVO is the most common type, accounting for about 75%.
Presentation:
Rapid unilateral blurred vision.
Visual Acuity (VA):
It is impaired to a moderate-severe degree.
Relative afferent pupillary defect (RAPD):
It is absent or mild (in contrast to ischemic CRVO).
Fundus Examination:
Tortuosity and dilatation of all branches of the central retinal vein, dot/blot and flame-
shaped haemorrhages, throughout all four quadrants and most numerous in the periphery.
Cotton wool spots, optic disc and macular edema are common.
Fluorescein Angiography (FA):
It shows delayed arteriovenous transit time, blockage by haemorrhages, good retinal capillary
perfusion and late leakage.
Recent non-ischemic central retinal vein occlusion. (A) Venous tortuosity and dilatation, and
extensive flame-shaped haemorrhages; (B) FA late phase shows blockage by blood, staining of
vessel wall but good capillary perfusion.
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Central Retinal Vein Occlusion (CRVO)
Old non-ischemic central retinal vein occlusion. (A) Disc collaterals and a few residual retinal
haemorrhages; (B) FA late phase shows diffuse hyperfluorescence due to chronic macular
edema.
Optical coherence tomography (OCT):
It demonstrates and allows quantification of the severity of macular edema and is a useful way
of monitoring its course or the response to treatment.
Course:
Most acute signs resolve over 6–12 months. Residual findings include disc collaterals, epiretinal
gliosis and pigmentary changes at the macula. Conversion to ischemic CRVO occurs in 15% of
cases within 4 months and 34% within 3 years.
Follow-up:
In a clearly non-ischemic occlusion, initial follow-up should take place after 3 months. Defined
arrangements for review of test results should be in place. The patient should be instructed to
make contact if the vision deteriorates as this may indicate the development of significant
ischemia. Pain or redness (may indicate neovascular glaucoma and occasionally inflammation
without rubeosis) should also be reported. Subsequent review is dependent on the clinical
picture, with discharge from follow-up usually at 18–24 months.
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Central Retinal Vein Occlusion (CRVO)
Prognosis:
In cases that do not subsequently become ischemic, the prognosis is reasonably good with
return of vision to normal or near normal in about 50%. The main cause for poor vision is
chronic macular edema, which may lead to secondary retinal pigment epithelium (RPE)
changes. To a certain extent the prognosis is related to initial visual acuity as follows:
6/18 or better, it is likely to remain so.
6/24–6/60, the clinical course is variable, and vision may subsequently improve, remain the
same, or worsen.
Worse than 6/60, improvement is unlikely.
Treatment of macular edema:
Laser photocoagulation:
It is not beneficial for macular edema.
Intravitreal steroid:
The score study showed an improvement in the vision of 3 or more lines at one year in over
25% of patients treated with an average of 2 injections of 1 mg triamcinolone versus 7% of
controls. A trial (GENEVA) of a 0.7 mg dexamethasone sustained-release biodegradable
intravitreal implant (Ozurdex®) showed substantial visual improvement over the first 2 months
following a single implantation, though this declined to baseline by 6 months.
Intravitreal anti-VEGF agents:
Ranibizumab showed a significant visual benefit when used for CME. Injections were given
monthly for 6 months and subsequently less intensively. Several uncontrolled case series
suggest that approximately 50% of patients improve 2 or more lines with intravitreal
bevacizumab, with 90% of eyes achieving stabilization of vision by 12 months. Pegaptanib also
shows promising results.
Experimental treatments:
Include chorioretinal anastomosis, vitrectomy with radial optic neurotomy or tissue
plasminogen activator (rTPA) local infusion.
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Central Retinal Vein Occlusion (CRVO)
Papillophlebitis
Papillophlebitis (optic disc vasculitis) is an uncommon condition which typically affects
otherwise healthy individuals under the age of 50 years. It is thought that the underlying lesion
is optic disc swelling with resultant secondary venous congestion rather than venous
thrombosis occurring at the level of the lamina cribrosa, as occurs in older patients.
Presentation:
Mild blurring of vision typically worse on waking.
Visual Acuity (VA):
Reduction is mild to moderate.
Relative afferent pupillary defect (RAPD):
It is absent.
Fundus Examination:
Disc edema, which may be associated with cotton wool spots, is the dominant finding.
Also present are venous dilatation and tortuosity with variable amount of retinal
haemorrhages, usually confined to the peripapillary area and posterior fundus.
Blind spot is enlarged on perimetry.
Fluorescein Angiography (FA):
It shows mild delay in arteriovenous transit time, hyperfluorescence due to leakage and good
capillary perfusion.
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Central Retinal Vein Occlusion (CRVO)
Optical coherence tomography (OCT):
It may show cystoid macular edema (CME).
Prognosis
The prognosis is excellent despite the lack of treatment. Eighty per cent of cases achieve a final
visual acuity of 6/12 or better. The remainder suffer significant and permanent visual
impairment as a result of macular edema.
REFERENCES:
Kanski Clinical Ophthalmology.
kanski Signs of Ophthalmology.
Pavan Langston Manual of Ocular Diagnosis and Therapy 5th edition.
Yanoff Ophthalmology 2nd edition.