CASE V

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CASE V

• CENTRAL RETINAL VEIN OCCLUSION

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Patient History 52yo female

• Cc Colorless, gray spot interfering with vision,
  OS. Began this morning, comes and goes.
• Pt reports no loss of vision, or flashing lights,
  OU.
• Pt being followed by PCP for fatigue,
  loopiness. Possible DM. Blood work ordered.

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Examination Results, I

• VA- 20/20 OU.
• PERRL (-)APD.
• Slit Lamp Exam
• Unremarkable.

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Dilated Fundus Exam

• OD, Unremarkable.
• Temporal swelling of optic disc, OS.
• Dilated retinal veins, OS.
• Mid-peripheral dot and blot hemes, OS.

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Fundus View, OD
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Fundus View, OS
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Symptoms of CRVO

• 50 years of age
• The patient may be asymptomatic, but often will
  complain of sudden painless unilateral loss of
  vision and/or visual field
• May complain of a sudden onset of floating spots
  or flashing lights.
• Acuity may range anywhere from 20/20 to finger
  counting.
• If vision loss is severe, there may be an APD.

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Signs

• Retinal edema.
• Superficial hemorrhages.
• Disc swelling.
• Cotton wool spots.
• Tortuous and dilated retinal veins.

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Predisposing Factors

• Glaucoma
• Papilledema
• Optic N. hemorrhage
• Optic N. drusen
• Vascular disease (DM, HTN)
• SLE
• Trauma
• Leukemia

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CRVO and Systemic Disease

• Carotid Artery Disease
• Antithrombin Deficiency
• Hypercholesteremia
• Hyperlipidemia
• Mitral Valve Prolapse
• Hypercoagulopathies

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CRVO and Age

• Under 50 years
• Head injury.
• Hyperlipidemia.
• Estrogen preparations.
• Over 50 years
• Hypertension.
• Hyperlipidemia.
• Abnormal glucose tolerance test.
• Hyperviscosity syndrome.

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Pathophysiology

• The exact pathogenesis of the thrombotic
  occlusion of the central retinal vein is not
  known.
• Various local and systemic factors play a role in
  the pathological closure of the central retinal
  vein.

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Pathogenesis of CRVO

• CRV/CRA anatomy.
• Compression induced changes in the vein
  turbulence, endothelial cell damage, thrombosis.

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Anatomy Review

• Central retinal artery and vein share a common
  adventitial sheath, as they exit the optic nerve
  head and pass through narrow opening in the
  lamina cribrosa.

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Arterial Disease and CRVO

• Arteriosclerotic changes in the central retinal
  artery.
• Becomes rigid and impinges upon the thinner vein,
  causing hemodynamic disturbances, endothelial
  damage, and thrombus formation.
• Expect associated arterial disease with CRVO.
  However, this association has not been proven
  consistently.

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Causes of Thrombotic Occlusion

• Compression of the vein (mechanical pressure due
  to structural changes in lamina cribrosa,
  glaucomatous cupping, inflammatory swelling in
  optic nerve, orbital disorders).
• Changes in blood (deficiency of thrombolytic
  factors, increase in clotting factors).
• Hemodynamic disturbances (hyperdynamic or
  sluggish circulation) vessel wall changes.

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More Pathophysiology

• Occlusion leads to backup of blood in the retinal
  venous system and increased resistance to venous
  blood flow and stagnation of blood resulting in
  ischemia of inner retinal layers.
• Increased blood pressure in the venous system
  causes break down of inner retinal barrier at the
  retinal capillary endothelium, leading to
  abnormal leakage of fluid in the retinal layers
  causing macular edema.
• Ischemic damage to the retina produces angiogenic
  factors, stimulates neovascularization.

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Neovascularization

• Neovascularization will form most typically the
  posterior iris.
• This can lead to rubeosis irides and neovascular
  glaucoma.
• Anterior segment neovascularization with
  associated neovascular glaucoma develops in more
  than 60 of ischemic cases, 20 for non-ischemic.
  
• Occurs within a few weeks and up to 1-2 years
  afterward.

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Ischemic v. Non-ischemic

• Primary difference involves presence of retinal
  hypoxia of ischemia.
• Ischemic characterized by at least 10DD of
  retinal capillary non-perfusion.
• Determined by fluorescein angiogram.

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10 DD Capillary Obliteration

• Studies have shown that this may be an invalid
  criterion for diagnosis of ischemic CRVO by
  fluorescein angiography.
• Study results shows that eyes with less than 30
  disc diameters of retinal capillary nonperfusion
  and no other risk factor are at low risk for
  developing iris/angle NV, whereas eyes with 75
  disc diameters or more are at highest risk.

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Normal FA
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Non-Ischemic CRVO
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Ischemic CRVO
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Ischemic v. Non-ischemic

• Ischemic CRVO
• Severe.
• Usually presents with severe visual loss
• Extensive retinal hemorrhages and cotton-wool
  spots.
• () APD
• Poor perfusion to retina.

• Non-Ischemic CRVO
• Milder.
• It may present with good vision.
• Few retinal hemorrhages and cotton-wool spots.
• (-) APD
• Good perfusion to the retina.

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Management, Ischemic

• Find underlying cause.
• Rule out glaucoma.
• Possible use of IOP-lowering agents.
• Possible need for anti-coagulation.
• Retinal consult, fluorescein angiography.
• Follow every 3-4 weeks for 6 months for
  development of NVG.

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Management, Non-ischemic

• Find underlying cause.
• Rule out glaucoma.
• Possible use of IOP-lowering agents.
• Possible need for anti-coagulation.
• Retinal consult, fluorescein angiography.
• Follow every 4 weeks for 6 months for conversion
  to ischemia.

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Finding Underlying Cause

• Blood pressure and pulse evaluation.
• Fasting blood glucose.
• Complete blood count with differentials and
  platelets.
• FTA-ABS
• Antinuclear antibodies
• Carotid palpitation and auscultation.

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Medical Care

• No known effective medical treatment is available
  for either prevention or the treatment of CRVO.
• Possibilities include Aspirin, Systemic
  anticoagulation with warfarin and heparin,
  Fibrinolytic agents, Systemic corticosteroids,
  Anti-inflammatory agents, Isovolumic
  hemodilution, Plasmapheresis.

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Definitions

• Plasmapheresis
• Selective removal of certain proteins or
  antibodies from the blood,followed by reinjection
  of the blood.
• Isovolumic hemodilution
• Removal of certain volume of blood replaced by
  same volume of saline.

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Surgical Care

• Neovascularization CVOS evaluated the efficacy
  of prophylactic PRP in ischemic eyes, in
  preventing development of 2 clock hours of iris
  neovascularization or any angle
  neovascularization.
• CVOS concluded that prophylactic PRP did not
  prevent the development of iris
  neovascularization.
• Recommended to wait for the development of early
  iris neovascularization and then apply PRP.

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Surgical Care, II

• Macular edema CVOS evaluated the efficacy of
  macular grid photocoagulation in preserving or
  improving central visual acuity in eyes with
  macular edema due to central vein occlusion (CVO)
  and best-corrected visual acuity of 20/50 or
  poorer.
• Macular grid photocoagulation was effective in
  reducing angiographic evidence of macular edema,
  but it did not improve visual acuity in eyes with
  reduced due to macular edema from CVO.

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Surgical Care, III

• Chorioretinal venous anastomosis bypasses the
  site of venous occlusion in the optic disc,
  creating a venous outflow channel to choroidal
  circulation.
• Retinal veins are punctured, either using laser
  or by surgery, through the RPE and Bruchs
  membrane into the choroid, developing anastomotic
  channels into the choroid.
• This reduces macular edema and may improve vision
  in non-ischemic CRVO.

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Thrombosis Location and Prognosis

• May be relative to risk of ischemia.
• Occlusions posterior to lamina may provide more
  venous collaterals and improved perfusion.

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Ischemic CRVO Prognosis

• More than 90 of patients will have 20/200 or
  worse vision.
• About 60 of patients develop ocular
  neovascularization with associated complications.
• About 10 of patients can develop CRVO or other
  type of vein occlusions either within the same
  eye or fellow eye within 2 years.

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Non-Ischemic CRVO Prognosis

• Complete recovery with good visual recovery
  occurs only in about 10 of cases.
• Fifty percent of patients will have 20/200 or
  worse vision.
• About one third of patients convert to ischemic
  CRVO within 3 years 15 convert within the first
  4 months.

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Fellow Eye Studies

• It has been reported that the fellow eye may
  develop retinal vein occlusion in about 7 of
  cases within 2 years.
• The 4-year risk of developing second venous
  occlusion is 2.5 in the same eye and 11.9 in
  the fellow eye.

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Under Investigation

• Intravitreal Steroid
• May improve macular edema, visual acuity.
• Vitrectomy
• Arteriovenous Sheathotomy
• Separate CRA from CRV
• Anti-VEGF Antibodies

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Under Investigation, II

• Radial Optic Neurotomy
• Attempts to decompress pressure at lamina
  opening.
• Involves an incision through the scleral ring and
  cribiform plate.
• Fibrotic tissue seems to fill void in early
  attempts.

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CVOS Summary Purpose

• To determine whether photocoagulation therapy can
  help prevent iris neovascularization in eyes with
  CVO and evidence of ischemic retina.
• To assess whether grid-pattern photocoagulation
  therapy will reduce loss of central visual acuity
  due to macular edema secondary to CVO.
• To develop new data describing the course and
  prognosis for eyes with CVO.

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CVOS Results

• Macular Edema - Macular grid photocoagulation was
  effective in reducing angiographic evidence of
  macular edema but did not improve visual acuity.
• Indeterminate Eyes with such extensive
  intraretinal hemorrhage that it is not possible
  to determine the retinal capillary perfusion
  status act as if they are ischemic or
  nonperfused.

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CVOS Results

• Non-ischemic CVO - Prophylactic panretinal
  photocoagulation did not prevent the development
  of iris neovascularization in eyes with 10 or
  more disc areas of retinal capillary
  nonperfusion. It is safe to wait for the
  development of early iris neovascularization and
  then apply panretinal photocoagulation.