Retinal Vein OcclusionsRetinal Vein Occlusions

MorphologyMorphology

CRVOCRVO BRVOBRVO Hemispheric VOHemispheric VO Hemicentral VOHemicentral VO PapillophlebitisPapillophlebitis Macular BRVOMacular BRVO

CENTRAL RETINAL VEIN CENTRAL RETINAL VEIN OCCLUSIONOCCLUSION

» The actual mechanisms The actual mechanisms producing the clinical producing the clinical picture of central retinal picture of central retinal vein occlusion may be vein occlusion may be roughly divided into those roughly divided into those conditions that produce a conditions that produce a physical blockage at the physical blockage at the level of the lamina level of the lamina cribrosa, and those cribrosa, and those conditions in which conditions in which hemodynamic factors hemodynamic factors result in an obstruction to result in an obstruction to the flow of blood. These the flow of blood. These mechanisms probably mechanisms probably coexist in many patients coexist in many patients with central VO.with central VO.

"Blood and thunder" appearance of a central retinal vein occlusion.

PATHOLOGY PATHOLOGY

Histopathologic evaluation of eyes removed Histopathologic evaluation of eyes removed because of a central retinal vein occlusion because of a central retinal vein occlusion demonstrates an occlusion at or just behind the demonstrates an occlusion at or just behind the level of the lamina cribrosa.level of the lamina cribrosa.

At this location, there are certain anatomic factors At this location, there are certain anatomic factors that predispose the central retinal vein to that predispose the central retinal vein to occlusion. First, the lumina of the central retinal occlusion. First, the lumina of the central retinal artery and central retinal vein are narrower than artery and central retinal vein are narrower than they are in the orbital optic nerve, and the vessels they are in the orbital optic nerve, and the vessels are bound by a common adventitial sheath.are bound by a common adventitial sheath.

Doppler StudiesDoppler Studies

Recently, color Doppler ultrasound imaging has been used to examine Recently, color Doppler ultrasound imaging has been used to examine the blood flow in the orbit, including the optic nerve head, and has the blood flow in the orbit, including the optic nerve head, and has been used to examine patients with central retinal vein occlusion.been used to examine patients with central retinal vein occlusion.

As might be expected, the venous velocity in the eye of a patient with As might be expected, the venous velocity in the eye of a patient with central retinal vein occlusion is markedly reduced compared either central retinal vein occlusion is markedly reduced compared either with the unaffected eye or to control eyes.with the unaffected eye or to control eyes.

There is evidence, however, that the central retinal artery blood flow is There is evidence, however, that the central retinal artery blood flow is also impaired in eyes with acute central retinal vein occlusion.also impaired in eyes with acute central retinal vein occlusion.

In addition, vascular resistance is slightly higher in the ophthalmic In addition, vascular resistance is slightly higher in the ophthalmic artery and short posterior ciliary arteries of both the involved and the artery and short posterior ciliary arteries of both the involved and the clinically healthy fellow eye of patients with central retinal vein clinically healthy fellow eye of patients with central retinal vein occlusion compared with control eyes.occlusion compared with control eyes.

There is also a trend toward higher vascular resistance of the central There is also a trend toward higher vascular resistance of the central retinal artery in the clinically healthy eyes of patients with central retinal artery in the clinically healthy eyes of patients with central retinal vein occlusion compared with control eyes.retinal vein occlusion compared with control eyes.

Risk FactorsRisk Factors

An increased risk of central retinal vein occlusion An increased risk of central retinal vein occlusion was found in patients with systemic hypertension, was found in patients with systemic hypertension, diabetes mellitus, and open-angle glaucoma; the diabetes mellitus, and open-angle glaucoma; the risk of central vein occlusion was decreased for risk of central vein occlusion was decreased for patients with increasing levels of physical activity patients with increasing levels of physical activity and increasing levels of alcohol consumption. and increasing levels of alcohol consumption.

For women, the risk decreased with the use of For women, the risk decreased with the use of postmenopausal estrogen and increased with a postmenopausal estrogen and increased with a higher erythrocyte sedimentation rate. higher erythrocyte sedimentation rate.

The Eye Disease Case-Control Study Group: Risk factors for central retinal vein occlusion.

Arch Ophthalmol 114:545, 1996

Risk Factors for Central Retinal Risk Factors for Central Retinal Vein OcclusionVein Occlusion

InvestigationsInvestigations

All patients with central retinal vein occlusion should have a comprehensive ophthalmic All patients with central retinal vein occlusion should have a comprehensive ophthalmic evaluation, including an appropriate evaluation for glaucoma. In addition, they should be evaluation, including an appropriate evaluation for glaucoma. In addition, they should be referred to their primary care physician for an evaluation of cardiovascular risk factors, referred to their primary care physician for an evaluation of cardiovascular risk factors, including hypertension and diabetesincluding hypertension and diabetes

GENERAL PRINCIPALSGENERAL PRINCIPALS

Maximise Recovery and VisionMaximise Recovery and Vision

Prevent re-occlusionPrevent re-occlusion

Detect associated systemic diseaseDetect associated systemic disease

Detect / Prevent GlaucomaDetect / Prevent Glaucoma

Protect other eyeProtect other eye

Standard InvestigationsStandard Investigations

FBC, PV, ESRFBC, PV, ESR U+E, CreatinineU+E, Creatinine LFT, Protein ElectrophoreseisLFT, Protein Electrophoreseis Random Glucose, LipidRandom Glucose, Lipid Urine analysisUrine analysis

Ophthalmic InvestigationsOphthalmic Investigations

FFAFFA CDI (Color doppler )CDI (Color doppler ) Carotid disease-Carotid disease-Using digital subtraction angiography, Brown and Using digital subtraction angiography, Brown and

associates studied 37 patients with central retinal vein occlusion; they found associates studied 37 patients with central retinal vein occlusion; they found that significant ipsilateral stenosis (greater than 50%) was not higher in these that significant ipsilateral stenosis (greater than 50%) was not higher in these patients compared with historically matched controls. They did find, however, patients compared with historically matched controls. They did find, however, that patients with ischemic central retinal vein occlusion had a higher that patients with ischemic central retinal vein occlusion had a higher incidence of overall carotid atherosclerotic obstruction (ipsilateral and incidence of overall carotid atherosclerotic obstruction (ipsilateral and contralateral) than patients with nonischemic central retinal vein occlusioncontralateral) than patients with nonischemic central retinal vein occlusion

Ischemic Central Retinal Vein Ischemic Central Retinal Vein Occlusion Occlusion

Patients with an ischemic pattern are usually Patients with an ischemic pattern are usually aware of a sudden, painless decrease in visual aware of a sudden, painless decrease in visual acuity. Vision ranges from 20/400 to hand acuity. Vision ranges from 20/400 to hand movements. The onset, however, is generally not movements. The onset, however, is generally not as rapid or the visual loss as extensive as in central as rapid or the visual loss as extensive as in central retinal artery occlusion. Exceptional cases have retinal artery occlusion. Exceptional cases have been noted in which patients with an acute onset been noted in which patients with an acute onset had reasonably good vision and yet demonstrated had reasonably good vision and yet demonstrated a picture of ischemic central retinal vein a picture of ischemic central retinal vein occlusion. Patients with ischemic occlusion have occlusion. Patients with ischemic occlusion have an average age of 68.5 years.an average age of 68.5 years.

Nonischemic Central Retinal Nonischemic Central Retinal Vein Occlusion Vein Occlusion

Nonischemic central retinal vein occlusion Nonischemic central retinal vein occlusion is a much milder and more variable disease is a much milder and more variable disease in appearance, symptoms, and course in appearance, symptoms, and course compared with ischemic central retinal vein compared with ischemic central retinal vein occlusion. Patients with nonischemic occlusion. Patients with nonischemic central retinal vein occlusion are an average central retinal vein occlusion are an average of 5 years younger (average age, 63 years) of 5 years younger (average age, 63 years) than those with ischemic vein occlusionthan those with ischemic vein occlusion

AngiographyAngiography The intravenous fluorescein angiogram pattern of an The intravenous fluorescein angiogram pattern of an

ischemic central retinal vein occlusion is usually ischemic central retinal vein occlusion is usually characterized by a delayed filling time of the venous characterized by a delayed filling time of the venous tree of the retina, capillary and venous dilation, and tree of the retina, capillary and venous dilation, and extensive leaking of fluorescein into the retina, extensive leaking of fluorescein into the retina, particularly in the macular area and in the area particularly in the macular area and in the area adjacent to the larger venous trunks and capillary adjacent to the larger venous trunks and capillary nonperfusion may not be noted at the time of initial nonperfusion may not be noted at the time of initial occlusion, but are usually manifest shortly thereafter. occlusion, but are usually manifest shortly thereafter. Late-phase photographs show patchy extravascular Late-phase photographs show patchy extravascular areas of fluorescence and staining of the retinal veins. areas of fluorescence and staining of the retinal veins. The intravenous fluorescein angiogram pattern of an The intravenous fluorescein angiogram pattern of an ischemic central retinal vein occlusion is usually ischemic central retinal vein occlusion is usually characterized by a delayed filling time of the venous characterized by a delayed filling time of the venous tree of the retina, capillary and venous dilation, and tree of the retina, capillary and venous dilation, and extensive leaking of fluorescein into the retina, extensive leaking of fluorescein into the retina, particularly in the macular area and in the area particularly in the macular area and in the area adjacent to the larger venous trunks and capillary adjacent to the larger venous trunks and capillary nonperfusion nonperfusion

Microaneurysms may not be noted at the time of initial Microaneurysms may not be noted at the time of initial occlusion, but are usually manifest shortly thereafter. occlusion, but are usually manifest shortly thereafter.

Late-phase photographs show patchy extravascular Late-phase photographs show patchy extravascular areas of fluorescence and staining of the retinal veins. areas of fluorescence and staining of the retinal veins. Fluorescence in the macula indicates capillary leakage Fluorescence in the macula indicates capillary leakage and edema; this not only may account for much of the and edema; this not only may account for much of the initial visual loss in the acute phase, but may initial visual loss in the acute phase, but may eventually result in permanent structural changes. eventually result in permanent structural changes.

Classifying ischaemiaClassifying ischaemia

The amount of nonperfusion or The amount of nonperfusion or ischemia is determined by ischemia is determined by inspecting the fluorescein inspecting the fluorescein angiography negative under angiography negative under magnification. The photographer magnification. The photographer inspects not only the central 30° or inspects not only the central 30° or 45°, but as much of the peripheral 45°, but as much of the peripheral retina as possible. retina as possible.

Another method has been to Another method has been to classify eyes with less than 10 disc classify eyes with less than 10 disc diameters of perfusion on diameters of perfusion on fluorescein angiography as fluorescein angiography as perfused or nonischemic, and eyes perfused or nonischemic, and eyes with 10 or more areas of with 10 or more areas of nonperfusion as nonperfused or nonperfusion as nonperfused or ischemic.ischemic.

Macular OedemaMacular Oedema

Fluorescence in the Fluorescence in the macula indicates macula indicates capillary leakage and capillary leakage and edema; this not only edema; this not only may account for much may account for much of the initial visual of the initial visual loss in the acute phase, loss in the acute phase, but may eventually but may eventually result in permanent result in permanent structural changes. structural changes.

Prognosis CRVOPrognosis CRVO

The prognosis for ischemic central retinal vein occlusion is The prognosis for ischemic central retinal vein occlusion is generally poor because of decreased visual acuity and generally poor because of decreased visual acuity and neovascularization. Visual loss occurs because of macular neovascularization. Visual loss occurs because of macular edema, capillary nonperfusion, overlying hemorrhage edema, capillary nonperfusion, overlying hemorrhage (either retinal or vitreal), or a combination of all of these. (either retinal or vitreal), or a combination of all of these. Retinal edema usually gradually subsides except in the Retinal edema usually gradually subsides except in the macula, where it may persist for many months or years. macula, where it may persist for many months or years. Macular holes or cysts may form.Macular holes or cysts may form.

NeovascularizationNeovascularization

The most serious complication of central retinal The most serious complication of central retinal vein occlusion is neovascularization. vein occlusion is neovascularization.

Neovascularization elsewhere (NVE) occurs less Neovascularization elsewhere (NVE) occurs less frequently than neovascularization of the iris frequently than neovascularization of the iris (NVI), and usually only in ischemic occlusions.(NVI), and usually only in ischemic occlusions.

The low incidence of retinal surface The low incidence of retinal surface neovascularization in ischemic central retinal vein neovascularization in ischemic central retinal vein occlusion is thought to be due to the destruction of occlusion is thought to be due to the destruction of endothelial cells, which provide the source for endothelial cells, which provide the source for endothelial proliferation and neovascularization. endothelial proliferation and neovascularization.

Percentage of Ocular Neovascularization Percentage of Ocular Neovascularization in Venous Occlusionin Venous Occlusion

Neovascularization of the Iris.Neovascularization of the Iris.

Neovascularization of the iris and frequently neovascular glaucoma occurs in Neovascularization of the iris and frequently neovascular glaucoma occurs in approximately 8%6to 25% of all central retinal vein occlusions and generally approximately 8%6to 25% of all central retinal vein occlusions and generally only in those eyes that exhibit an ischemic pattern of occlusion.only in those eyes that exhibit an ischemic pattern of occlusion.

Magargal and co-workers have shown that the incidence of neovascularization Magargal and co-workers have shown that the incidence of neovascularization increases dramatically above approximately 50% capillary nonperfusion. The increases dramatically above approximately 50% capillary nonperfusion. The incidence of anterior segment neovascularization in nonischemic central incidence of anterior segment neovascularization in nonischemic central retinal vein occlusion is approximately 1%, compared with approximately retinal vein occlusion is approximately 1%, compared with approximately 35% to 45% for ischemic central retinal vein occlusion.35% to 45% for ischemic central retinal vein occlusion.

Neovascularization of the iris or angle is significantly correlated with the Neovascularization of the iris or angle is significantly correlated with the extent of capillary nonperfusion on the fluorescein angiogram. extent of capillary nonperfusion on the fluorescein angiogram.

Rubeosis developed in 80% to 86% of the eyes with severe nonperfusion of Rubeosis developed in 80% to 86% of the eyes with severe nonperfusion of three to four quadrants of the posterior pole or the periphery, but in only 3% to three to four quadrants of the posterior pole or the periphery, but in only 3% to 9% of those with less capillary nonperfusion. 9% of those with less capillary nonperfusion.

HEMICENTRAL AND HEMISPHERIC HEMICENTRAL AND HEMISPHERIC

RETINAL VEIN OCCLUSIONRETINAL VEIN OCCLUSION The terms hemicentral retinal vein occlusion and The terms hemicentral retinal vein occlusion and

hemispheric retinal vein occlusion refer to eyes in which hemispheric retinal vein occlusion refer to eyes in which approximately half of the venous outflow from the retina, approximately half of the venous outflow from the retina, either the superior or the inferior, has been occluded. In either the superior or the inferior, has been occluded. In approximately 20% of eyes, the branch retinal veins approximately 20% of eyes, the branch retinal veins draining the superior and inferior halves of the retina enter draining the superior and inferior halves of the retina enter the lamina cribrosa separately before joining to form a the lamina cribrosa separately before joining to form a single central retinal vein.single central retinal vein.

Hemicentral retinal vein occlusion is an occlusion of one Hemicentral retinal vein occlusion is an occlusion of one of these dual trunks of the central retinal vein within the of these dual trunks of the central retinal vein within the nerve. Hemispheric retinal vein occlusion is an occlusion nerve. Hemispheric retinal vein occlusion is an occlusion involving the venous drainage from approximately half of involving the venous drainage from approximately half of the retina, either the superior or the inferior retinathe retina, either the superior or the inferior retina

Hemispheric retinal vein Hemispheric retinal vein occlusionsocclusions

In some eyes, the nasal retina is not drained by a separate vein, but by In some eyes, the nasal retina is not drained by a separate vein, but by a branch of either the superior or the inferior temporal vein. It is the a branch of either the superior or the inferior temporal vein. It is the occlusion of one of these veins draining both the nasal retina and the occlusion of one of these veins draining both the nasal retina and the superior or inferior retina near the optic disc that accounts for the superior or inferior retina near the optic disc that accounts for the majority of hemispheric retinal vein occlusions. majority of hemispheric retinal vein occlusions.

The treatment and classification are similar to that of branch retinal The treatment and classification are similar to that of branch retinal vein occlusion. vein occlusion.

BRANCH RETINAL VEIN BRANCH RETINAL VEIN OCCLUSION OCCLUSION

PATHOLOGY Leber was probably the first investigator to note the connection between branch retinal vein occlusion and the arteriovenous intersection. Koyanagi found that the majority (77.7%) of his cases of temporal vein occlusion involved the superior retina. He attributed this to the preponderance of arteriovenous crossings in this region compared with other quadrants.Others later confirmed this anatomic observation, noting that branch retinal vein occlusion always occurs at an arteriovenous intersection.Both fluorescein angiography1and histopathologic examination confirm that most occlusions occur at an arteriovenous crossing and that the few that do not are in the vicinity of a retinal artery. Histologically, where the vein and artery cross, they share a common adventitial sheath, and the venous lumen may be diminished by as much as a third at this crossing.

MorphologyMorphology

The clinical picture of branch retinal vein occlusion is The clinical picture of branch retinal vein occlusion is retinal hemorrhages that are segmental in distribution. retinal hemorrhages that are segmental in distribution.

The apex of the obstructed tributary vein almost The apex of the obstructed tributary vein almost always lies at an arteriovenous crossing. Usually always lies at an arteriovenous crossing. Usually some degree of pathologic arteriovenous nicking is some degree of pathologic arteriovenous nicking is present.present.

The occlusion is commonly located one or two disc The occlusion is commonly located one or two disc diameters away from the optic disc. However, the diameters away from the optic disc. However, the occlusion may lie at a point near the disc edge or, less occlusion may lie at a point near the disc edge or, less frequently, may involve one of the smaller, more frequently, may involve one of the smaller, more peripheral tertiary or macular branches. peripheral tertiary or macular branches.

Risk Factors for Branch Retinal Risk Factors for Branch Retinal Vein OcclusionVein Occlusion

Systemic hypertensionSystemic hypertension

History of History of cardiovascular diseasecardiovascular disease

Increased body mass index at Increased body mass index at 20 years of age20 years of age cholesterolcholesterol

History of glaucomaHistory of glaucoma

High serum levels ofHigh serum levels ofa2-globulina2-globulin

Management of BRVOManagement of BRVO

Branch vein obstruction is often associated with Branch vein obstruction is often associated with pre-existing vascular disease. Evaluation for pre-existing vascular disease. Evaluation for systemic abnormalities, in particular hypertension, systemic abnormalities, in particular hypertension, should be performed. Exclusion of diabetes, should be performed. Exclusion of diabetes, hyperlipidaemia, hyperviscosity/coagulation states, hyperlipidaemia, hyperviscosity/coagulation states, antiphospholipid syndrome, or any other antiphospholipid syndrome, or any other predisposing condition should be performed. predisposing condition should be performed. Regular review is required until the haemorrhages Regular review is required until the haemorrhages clear so that the most suitable treatment option can clear so that the most suitable treatment option can be achieved. Approximately one third to one half of be achieved. Approximately one third to one half of patients with BRVO have recovery of visual acuity patients with BRVO have recovery of visual acuity to 20/40, or better, without therapy. to 20/40, or better, without therapy.

An important complication of branch An important complication of branch retinal vein occlusion is retinal vein occlusion is

neovascularizationneovascularization Neovascularization of the iris and neovascular glaucoma are Neovascularization of the iris and neovascular glaucoma are

uncommon and occur in only approximately 1% of affected eyes.uncommon and occur in only approximately 1% of affected eyes. More commonly, neovascularization of the disc occurs in More commonly, neovascularization of the disc occurs in

approximately 10% of eyes, and neovascularization elsewhere occurs approximately 10% of eyes, and neovascularization elsewhere occurs in approximately 20% of eyes. Generally, retinal neovascularization in approximately 20% of eyes. Generally, retinal neovascularization occurs within the retinal area served by the occluded vessel, but it has occurs within the retinal area served by the occluded vessel, but it has been reported to occur outside in presumably normal retina.been reported to occur outside in presumably normal retina.

Vitreous hemorrhage due to neovascularization occurs in Vitreous hemorrhage due to neovascularization occurs in approximately half of the eyes with neovascularization.Butner and approximately half of the eyes with neovascularization.Butner and McPherson239 found that 11.3% of spontaneous vitreous hemorrhages McPherson239 found that 11.3% of spontaneous vitreous hemorrhages were due to a branch retinal vein occlusion, an incidence second only were due to a branch retinal vein occlusion, an incidence second only to proliferative diabetic retinopathy as a cause of vitreous hemorrhage. to proliferative diabetic retinopathy as a cause of vitreous hemorrhage.

Oyakawa and co-workers found that in 38.3% of eyes undergoing a Oyakawa and co-workers found that in 38.3% of eyes undergoing a vitrectomy for a nondiabetic vitreous hemorrhage, the hemorrhaging vitrectomy for a nondiabetic vitreous hemorrhage, the hemorrhaging was due to a branch retinal vein occlusion.was due to a branch retinal vein occlusion.

MACULAR BRANCH MACULAR BRANCH RETINAL VEIN OCCLUSION RETINAL VEIN OCCLUSION

An occlusion limited to a small venous tributary draining a section of An occlusion limited to a small venous tributary draining a section of the macula and located between the superior and inferior temporal the macula and located between the superior and inferior temporal arcades is considered a subgroup of branch retinal vein occlusion.Most arcades is considered a subgroup of branch retinal vein occlusion.Most patients with macular branch vein occlusion complain of blurring or patients with macular branch vein occlusion complain of blurring or distortion of vision. Superior macular vein occlusions are more distortion of vision. Superior macular vein occlusions are more common than inferior macular vein occlusions, and some degree of common than inferior macular vein occlusions, and some degree of macular edema is present in approximately 85% of these eyes.macular edema is present in approximately 85% of these eyes.

Although small areas of capillary nonperfusion are present in Although small areas of capillary nonperfusion are present in approximately 20% of eyes, neovascularization is not seen. This type approximately 20% of eyes, neovascularization is not seen. This type of macular vein occlusion can be remarkably subtle at times. Joffe and of macular vein occlusion can be remarkably subtle at times. Joffe and associates pointed out that clues such as small collateral channels and associates pointed out that clues such as small collateral channels and microaneurysms often suggest the diagnosis. Treatment of macular microaneurysms often suggest the diagnosis. Treatment of macular edema in macular vein occlusion by photocoagulation is identical to edema in macular vein occlusion by photocoagulation is identical to the treatment of other branch retinal vein occlusion. the treatment of other branch retinal vein occlusion.

Macular Oedema- FFAMacular Oedema- FFA

Investigations and therapyInvestigations and therapy

GENERAL PRINCIPALSGENERAL PRINCIPALS Maximise Recovery and VisionMaximise Recovery and Vision Prevent re-occlusionPrevent re-occlusion Detect any associated systemic diseaseDetect any associated systemic disease Detect / Prevent GlaucomaDetect / Prevent Glaucoma Protect other eyeProtect other eye

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