Difference between revisions of "Elevated Episcleral Venous Pressure (EVP)"

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{{Article
 
{{Article
|Authors=Alexander Foster, Christine.A.Petersen, Joanne.C.Wen
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|Authors=Alexander.A.Foster,Christine.A.Petersen,Joanne.C.Wen
 
|Category=Glaucoma
 
|Category=Glaucoma
|Reviewer=Christine.A.Petersen
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|Assigned editor=Ian.Conner
|Date reviewed=August 14, 2016
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|Reviewer=Ian.Conner
|Local Videos=
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|Date reviewed=November 11, 2019
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|Article status=Up to Date
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{{Infobox disease
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| Name = {{PAGENAME}}
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| DiseasesDB =
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| ICD9 =
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| ICD10 = {{ICD10|H|40|8|11}}
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| OMIM = 137700
 
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= Disease Entity  =
 
= Disease Entity  =
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Elevated episcleral venous pressure (EVP) is a clinical finding which may be associated with elevated intraocular pressure (IOP) and glaucoma if left chronically untreated. In many cases the diagnosis is secondary to an underlying etiology, however it can also be idiopathic if all other causes are excluded. The idiopathic form can be familial or sporadic. In German literature idiopathic elevated EVP leading to secondary open angle glaucoma has been termed Radius-Maumenee Syndrome<ref name=":0">Rhee DJ, Gupta M, Moncavage MB,
 +
Moster ML, Moster MR. Idiopathic elevated episcleral venous pressure and open
 +
angel glaucoma. ''Br J Ophthalmol. ''2009;93(2):231-234.    </ref>.
  
Elevated episcleral venous pressure (EVP) is a clinical finding which may be observed in a variety of primary conditions. It can also bean be idiopathic, although this is a diagnosis of exclusion. In either case, elevated EVP may be associated with elevated intraocular pressure (IOP) and glaucoma. Idiopathic elevated EVP leading to secondary open angle glaucoma is also known as Radius-Maumenee syndrome in German literature.<ref>Rhee DJ, Gupta M, Moncavage MB, Moster ML, Moster MR. Idiopathic elevated episcleral venous pressure and open-angle glaucoma. British Journal of Ophthalmology. 2009 Feb 1;93(2):231-4.</ref>
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== Pathophysiology ==
  
== Disease ==
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Based on the Goldmann equation, intraocular pressure (IOP) is the rate of aqueous humor production divided by the facility of outflow plus EVP<ref name=":1">Moster M, Ichpujani P. Episcleral venous pressure, and glaucoma. . ''Journal of Current Glaucoma Practice ''1996;3:1143-1155    </ref>. The average EVP ranges from 8-10 mmHg<ref>Allingham RR, Damji KF, Freedman SF, Moroi SE, Rhee DJ, Shields MB. ''Shields textbook of Glaucoma ''2012.    </ref>, although can transiently change based on head positioning<ref>Arora N, McLaren JW, Hodge DO, Sit AJ. Effect of Body Position on Episcleral Venous Pressure in Healthy Patients. ''Invest Ophthalmol Vis Sci. ''2017;58(12):5151-5156.    </ref>. In the acute setting, there is a linear relationship and 1 mmHg rise in EVP correlates to a 1 mmHg rise in IOP<ref name=":2">Cioffi GA, Durcan FJ, Girkin CA. Basic and Clinical Science Course: Glaucoma. San Francisco: American Academy of Ophthalmology. 2013;26.    </ref>.  However, this relationship is not as well understood in chronic cases.  
  
Average EVP ranges from 8-10 mmHg, although it can transiently elevate with downward displacement of the head.<ref>Allingham RR, Damji KF, Freedman SF, Moroi SE, Rhee DJ, Shields MB. Shields textbook of glaucoma. Lippincott Williams & Wilkins; 2012 Mar 28.</ref> Persistently elevated EVP is a known cause of open-angle glaucoma as it can lead to obstruction of the aqueous drainage into the orbital venous system.<ref name=":0">Craven ER. Raised episcleral venous pressure. Ophthalmology. 2008.</ref> If not caught early it can lead to an insidious onset of glaucoma and subsequent vision loss.<ref name=":1">Parikh RS, Desai S, Kothari K.
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In the conventional drainage pathway, aqueous humor flows through the efferent channels of the canal of Schlemm and then through the anterior ciliary venous circulation before converging with the episcleral venous plexus at Tenon’s capsule and the conjunctiva. Given the paucity of capillary networks in episcleral vessels, arteriovenous vasculature anastomosis predominate<ref name=":1" />. The aqueous in the episcleral venous plexus will then drain into the superior ophthalmic vein and enters the cavernous sinus above the annulus of Zinn, before flowing into the internal jugular vein and into the right atrium via the superior vena cava<ref>Higginbotham EJ. ''Glaucoma associated with increased episcleral venous pressure.'' Philadelphia WB Saunders 2000.    </ref><ref name=":3">Rong X, Li M. Advanced glaucoma secondary to bilateral idiopathic dilated episcleral veins - a case report ''BMC Ophthalmology ''2018;18:207.    </ref>. Any obstruction along this pathway may cause elevated EVP.
Dilated episcleral veins with secondary open-angle glaucoma. Indian journal ofophthalmology. 2011 Mar;59(2):153.</ref> Idiopathic elevated EVP was first described in 1968 by Thomas Minas and Steven Podos in a case report of a family with two members found to have the condition after ruling out primary entities known to cause secondary elevated EVP.<ref name=":2">Minas TF, Podos SM. Familial glaucoma associated with elevated episcleral venous pressure. Archives of Ophthalmology. 1968 Aug 1;80(2):202-8.    </ref>
 
  
== Etiology  ==
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If there is increased venous pressure downstream to the episcleral anastomoses, then there is subsequent decrease in outflow of blood from the orbit and aqueous. Thus, in chronic cases, elevated EVP can cause blood reflux into Schlemm’s canal. This can subsequently raise IOP chronically, which can lead to glaucomatous damage due to secondary open angle glaucoma<ref>Minas TF, Podos SM. Familial glaucoma associated with elevated episcleral venous pressure. ''Archives of Ophthalmology ''1980;80(1):202-208.</ref>.
  
The Goldmann equation describes intraocular pressure (IOP) as the rate of aqueous humor production divided by the facility of outflow plus EVP.<ref name=":3">Moster M, Ichpujani P. Episcleral venous pressure, and glaucoma. Journal
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== Etiology  ==
of Current Glaucoma Practice. 1996;3(1):1143-55.    </ref> In the acute setting, IOP rises 1 mmHg for every 1 mmHg increase in EVP.<ref name=":4">Cioffi GA, Durcan FJ, Girkin CA. Basic and Clinical Science Course: Glaucoma. San Francisco: American Academy of Ophthalmology. 2013:26.    </ref>  However, the relationship between IOP and elevated EVP in chronic conditions is less well understood. Chronically elevated EVP can cause blood to reflux into Schlemm’s canal, which can decrease the facility of outflow of aqueous into the trabecular meshwork and subsequently raise the IOP.  
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Etiologies can range from venous obstruction to arteriovenous anomalies and can be acute or chronic in nature. It is important to elicit the timing of any trauma and do a full review of systems, including any previous infectious exposures, to rule out life or vision threatening causes of elevated EVP.  
  
Etiologies leading to elevated EVP are numerous and can be divided into several subcategories including venous obstruction, arteriovenous anomalies, and idiopathic pathologies.<ref name=":5">Higginbotham EJ. Glaucoma associated with increased episcleral venous
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{| class="wikitable"
pressure. Principles and practice of ophthalmology. WB Saunders, Philadelphia.
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2000:2781-92. </ref><ref>Weinreb RN, Jeng S, Goldstick BJ: Glaucoma secondary to elevated episcleral venous pressure. In: Ritch R, Shields MB, Krupin T, (eds): The glaucomas. St. Louis: CV Mosby; 1989: p 1130.      </ref><ref>Nelson GA, Edward DP, Wilensky JT. Ocular amyloidosis and secondary glaucoma. Ophthalmology. 1999 Jul 1;106(7):1363-6. </ref> Patients may endorse a distant history of craniofacial trauma that might suggest the cause of a carotid cavernous sinus, dural fistula, or other arteriovenous anomaly.<ref name=":4" />  Potential causes of elevated EV include:
+
  !
* Venous Obstruction
+
Venous Obstruction  
** Retrobulbar tumor
+
 
** Orbital amyloidosis
+
  !
** Thyroid ophthalmopathy
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Arteriovenous Anomalies  
** Jugular vein obstruction
+
 
** Congestive heart failure
+
  !
** Thrombosis of cavernous sinus or orbital vein
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Idiopathic 
** Vasculitis involving episcleral vein or orbital vein
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** Superior vena cava syndrome (mediastinal tumor)
+
|-
* Arteriovenous Anomalies
+
  |
** Carotid-cavernous sinus fistula
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Retrobulbar Tumor
** Orbital varix
 
** Sturge–Weber syndrome
 
** Orbital–meningeal shunts
 
** Carotid–jugular venous shunts
 
** Intraocular vascular shunts
 
* Idiopathic
 
** Sporadic
 
** Familial
 
  
== Risk Factors  ==
+
Orbital Amyloidosis
  
Any history of head trauma is a risk factor for developing a carotid cavernous sinus, dural fistula or other arteriovenous anomaly which can lead to the development of elevated EVP.<ref name=":4" />
+
Thyroid Ophthalmopathy 
  
== Pathophysiology  ==
+
Jugular Vein Obstruction
  
Branches of the anterior ciliary venous circulation system anastomose with efferent channels of the canal of Schlemm before converging with the episcleral venous plexus of Tenon's capsule and the conjunctiva. With very few capillary networks present in the angioarchitecture of the episcleral vessels, arteriovenous vasculature anastomoses predominate.<ref name=":3" /> The episcleral venous plexus will ultimately drain into the ophthalmic veins, which then drain into the cavernous sinus.<ref name=":5" />
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Congestive Heart Failure
 
Increased venous pressure downstream to the episcleral anastomoses leads to decreased outflow of venous blood from the orbit and decreased outflow of aqueous. A subsequent pressure difference across the trabecular meshwork occurs, lowering aqueous egress. Elevated EVP resulting in chronic IOP elevations can then lead to glaucomatous damage and the eventual diagnosis of secondary open angle glaucoma.<ref name=":2" />
 
  
= Diagnosis  =
+
Thrombosis of cavernous sinus or orbital vein
  
== History  ==
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Vasculitis involving episcleral or orbital vein
  
Patients with elevated EVP may be entirely unaware of their condition or the underlying cause. They generally present without typical glaucomatous signs or symptoms early in their disease. Patients may endorse a distant history of craniofacial trauma that might suggest the cause of a carotid cavernous sinus, dural fistula or any other arteriovenous anomaly.<ref name=":4" /> It is important to review the patient’s medical history, particularly for conditions such as amyloidosis, hyperthyroidism, congestive heart failure, hypercoagulable states, vasculitis, superior vena cava syndrome, Sturge–Weber syndrome, or other arteriovenous anomalies which may suggest an underlying cause for the elevated EVP.
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Superior Vena Cava Syndrome (Mediastinal Tumor)
 
+
 
== Physical examination  ==
+
  |
 +
Carotid-Cavernous Sinus Fistula (acute vs. chronic)
  
A clinical diagnosis of elevated EVP can be suspected when a patient presents with chronically injected episcleral vessels without a history of pain or irritation (Fig. 1).<ref name=":4" /> Elevated EVP can lead to small concentrations of blood reflux seen in Schlemm’s canal on gonioscopy.<ref name=":roll">Roll P, Benedikt O. Dilatation and tortuosity of episcleral vessels in open angle glaucoma. II. Electron microscopy study of the trabecular meshwork [in German]. Klin Monatsbl Augenheilkd. 1980;176:297-301.
 </ref> Hyalinization of the inner wall of Schlemm’s canal can occur secondary to this chronic accumulation of blood in the canal.<ref name=":roll"/>Additionally, if ischemia has occurred, neovascularization of the iris can be present.<ref>Harris MJ, Fine SL, Miller NR. Photocoagulation treatment of proliferative retinopathy secondary to a carotid-cavernous fistula. American Journal of Ophthalmology. 1980;90(4):515-8.</ref> It should be noted that blood in Schlemm’s canal, hyalinization of the inner wall, and neovascularization of the iris are all not specific for elevated EVP, but one should have raised suspicions of elevated EVP should they occur. It is of particular importance to be suspicious of elevated EVP in patients with unilateral dilated episcleral vessels.<ref>Lanzl IM, Welge-Luessen U, Spaeth GL. Unilateral open-angle glaucoma secondary to idiopathic dilated episcleral veins. American Journal of Ophthalmology. 1996 May 31;121(5):587-9.    </ref> Elevated EVP can be present bilaterally, but most commonly presents unilaterally as the condition is commonly a sequela of ipsilateral localized anatomical variants.<ref name=":0" />
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Dural  
  
Other physical exam findings include chemosis, proptosis, and an orbital bruit. However, these are less reliable findings and their presence can depend on the underlying conditions leading to elevated EVP.<ref>Allingham RR, Damji KF, Freedman SF, Moroi SE, Rhee DJ, Shields MB. Shields Textbook of Glaucoma. Lippincott Williams & Wilkins; 2012 Mar 28.    </ref>  Pulsatile exophthalmos may be seen when elevated EVP is associated with a carotid-cavernous fistula.<ref>Heichel J, Hammer T, Solymosi L, Brandt S, Winter I. Pressure-Lowering Effect of Fistula Occlusion in a Patient with Secondary Glaucoma Due to an
+
Orbital Varix
Intracranial Arteriovenous Fistula. Ophthalmology and therapy. 2015 Dec 1;4(2):135-41.    </ref> In elevated EVP, glaucomatous optic atrophy and visual field loss can be more insidious than other acute forms of glaucoma.
 
[[File:Corkscrew Vessels in EVP.jpeg|thumb|Fig 1. Corkscrew vessels in elevated episcleral venous pressure.]]
 
  
== Diagnostic procedures  ==
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Sturge-Weber Syndrome
  
Elevated EVP is often the result of another underlying disorder. A complete workup of the patient with elevated EVP to rule out underlying causes may include ultrasound biomicroscopy, orbital ultrasonography, computerized axial tomography, magnetic resonance imaging, chest x-ray and angiography.<ref name=":3" /><ref>Kranemann CF, Pavlin CJ, Trope GE. Ultrasound biomicroscopy in Sturge-Weber-associated glaucoma. American Journal of Ophthalmology. 1998 Jan 31;125(1):119-21.    </ref> Only after this workup is completed and negative may the patient be considered to have idiopathic elevated EVP.
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Orbital-meningeal shunts
  
There are several different diagnostic modalities which may be used to measure the EVP, though many of these are not routinely performed clinically. These include one direct method (cannulation), and three indirect methods (venomanometer pressure chamber, torsion balance, and air jet). The most accurate of these is direct cannulation, and the most accurate form of the indirect method is venomanometer.<ref name=":0" /><ref name=":6">Brubaker RF. Determination of episcleral venous pressure in the eye: a comparison of three methods. Archives of Ophthalmology. 1967 Jan 1;77(1):110-4.</ref> Other investigators have also used color-coded Doppler sonography to measure blood pulsation from the ophthalmic veins.<ref>Cymbor M, Knapp E, Carlin F. Idiopathic Elevated Episcleral Venous Pressure with Secondary Glaucoma. Optometry & Vision Science. 2013 Jul
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Carotid-jugular shunts
1;90(7):e213-7.    </ref>
+
 
 +
  |
 +
Sporadic 
  
'''Direct Cannulation.''' This method includes insertion of a cannula into an episcleral vein. These veins range in diameter from 50-100 micrometers, and investigators have used two different cannulation methods: complete and partial vessel occlusion. In the complete occlusion method, plastic tubing is employed to occlude an episcleral vessel completely. In the partial vessel occlusion method, a glass pipette with a beveled 2-5 micrometer tip is placed in the episcleral vessel. For best measurements, the cannula must face downstream.<ref name=":7">Sit AJ, McLaren JW. Measurement of episcleral venous pressure. Experimental eye research. 2011 Sep 30;93(3):291-8.    </ref>
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Familial 
 +
 +
|}
  
'''Venomanometer Pressure Chamber.''' In short, the venomanometer pressure chamber method requires a particular apparatus to be attached to the slit lamp with a chamber consisting of an encased, highly distensible and transparent membrane, which is applied to the conjunctiva at a preselected episcleral vessel. The pressure within the chamber is slowly increased until a subjective endpoint of a collapsed episcleral vein is observed.<ref name=":6" /> Several membranes have been utilized in this technique including latex, serosal membrane, frog pericardium, and silicone rubber. This is the most common non-invasive method for determining EVP in part due to its commercial availability (marketed as Episcleral Venomanometer, Model EV-310, EyeTech Ltd, Morton Grove, IL).<ref name=":7" />
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== Risk Factors  ==
  
T'''orsion Balance.''' This method requires a particular torsion balance instrument (very similar to the Goldmann applanation tonometer) to be mounted to the slit lamp. The applanation surface of the instrument has a diameter of 300 micrometers and is placed directly on the conjunctiva.<ref name=":6" />  Magnification is set at 25 to 40X and force is applied until a subjective endpoint of a collapsed episcleral vein is observed. Being that the area of the applanation surface is fixed, EVP can be determined by the force required to collapse the vessel.<ref name=":7" />
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Any history of head trauma is a risk factor for developing a carotid cavernous sinus, dural fistula or other arteriovenous anomaly which can lead to the development of elevated EVP.
  
'''Air Jet.''' Similar to the venomanometer and torsion balance methods, the air jet also utilizes a subjective endpoint of a collapsed episcleral vein by an applied pressure in this case administered via an air jet.<ref name=":7" />
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= Diagnosis  =
  
== Laboratory test ==
+
== History ==
 +
Typically, when patients present for evaluation of elevated EVP it is due to chronic eye redness that has not responded to previous treatment and often is misdiagnosed as chronic conjunctivitis<ref name=":2" />. They are usually unaware of their condition or underlying cause and typically do no describe pain or irritation. It is important to ask about recent trauma, specifically craniofacial, that can suggest a carotid cavernous sinus (high flow) or dural (low flow) fistula<ref name=":2" /><ref name=":4">Girkin CA, Bhorade AM, Crowton JG, et al. ''Glaucoma ''United States of America 2018.    </ref>. A complete past medical history should be obtained to rule out etiologies that may cause venous obstruction, including but not limited to hyperthyroidism, amyloidosis, congestive heart failure, hypercoagulable states, vasculitis, superior vena cava syndrome and Sturge-Weber Syndrome.
  
There is currently no laboratory test routinely used to suggest a patient has elevated EVP.  Lab testing may be used as needed to evaluate for any underlying conditions.
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== Physical examination ==
  
== Differential diagnosis  ==
+
Clinical exam is the gold standard for diagnosing elevated EVP. Typically, on physical examination, the episclera is injected and demonstrates the pathognomonic corkscrew episcleral vessels without inflammation (Figure 1). It is important to perform gonioscopy, which can show an open angle with blood reflux in Schlemm’s canal or hyalinization of the wall of Schlemm’s canal due to chronic accumulation of blood<ref name=":5">Roll P, Benedikt O. Dilatation and tortuousity of episcleral vessels in open angle glaucoma II. Electron microscopy study of the trabecular meshwork ''Klin Monatsbl Augenheikd. ''1980;176:297-301.</ref>. Other signs include chemosis, proptosis and the presence of an orbital bruit, however these are specific signs for elevated EVP<ref name=":5" />. If the elevated EVP is secondary to a carotid-cavernous fistula, then pulsatile exophthalmos can sometimes be seen<ref>Heichel J, Hammer T, Solymosi L, Brandt S, Winter I. Pressure-Lowering Effect of Fistula Occlusion in a Patient with Secondary Glaucoma due to an Intracranial Arteriovenous Fistula. ''Ophthalmology and Therapy. ''2015;4(2):135-141.</ref>. Intraocular pressure (IOP) can often times be elevated in the affected eye. Ancillary testing would include a optic coherence tomography (OCT) scan and Humphrey Visual Field testing to assess for glaucomatous changes. [[File:Corkscrew Vessels in EVP.jpeg|thumb|Fig 1. Corkscrew vessels in elevated episcleral venous pressure.]]
  
The differential diagnosis for elevated EVP includes entities that present with prominent ocular vessels.  Elevated EVP tends to present with larger caliber, more tortuous vessels than many of the following etiologies. Other differential diagnosis for a chronically injected eye includes:
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== Differential Diagnosis:   ==
* Ataxia telangiectasia
+
* [[Episcleritis]]
* Acute closed angle glaucoma
+
* [[Scleritis]]
* Scleritis
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* [[Conjunctivitis]]
* Episcleritis
+
* Ataxia Telangiectasia
* Conjunctivitis
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* Acute Closed Angle Glaucoma
* Rosacea
+
* Rosacea  
* Episcleral nodule
+
* Episcleral Nodule
* Cornea lesion near the limbus
+
* Corneal lesion near limbus  
 
* Foreign body
 
* Foreign body
* Herpetic keratitis
+
* Herpetic Keratitis
* Uveal neoplasm
+
* Uveal Neoplasm
 
* Polycythemia vera
 
* Polycythemia vera
* Leukemia<ref name=":0" /><ref>Bagheri N, Wajda B, Calvo C, Durrani A. The Wills Eye Manual: Office and
+
* Leukemia<ref>Bagheri N, Wajda BN, Calvo CM, Durrani AK. ''The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease ''Philadelphia Lippincott Williams & Wilkins 2017.    </ref>
Emergency Room Diagnosis and Treatment of Eye Disease. Lippincott Williams & Wilkins; 2016 Apr 19.    </ref>
+
 
 +
== Diagnostic procedures  ==
 +
A complete workout to rule out underlying etiology should be done when elevated EVP is suspected. In the setting of detecting an arteriovenous fistula, cerebral angiography is the gold standard, however orbital Doppler ultrasound is a non-invasive method which can confirm dilation of the superior ophthalmic vein<ref name=":3" />. Other modalities for diagnosis include orbital ultrasound, ultrasound biomicroscopy (UBM), computerized axial tomography and magnetic resonance imaging.
 +
 
 +
There are diagnostic modalities that measure EVP however are not routinely used in clinical practice. Direct cannulation is a direct method and can be done with the complete occlusion or partial vessel occlusion method; this is the most accurate test. Indirect methods include the venomanometer pressure chamber, torsion balance and air jet. Of the indirect methods the venomanometer is the most accurate.   
  
 
= Management  =
 
= Management  =
  
The management of elevated EVP can be medical or surgical. Care should be taken first to address any primary medical condition that might have caused the elevated EVP and would require specific treatment.
+
The aim of management should revolve around first treating the primary underlying etiology. If no etiology is determined for the elevated EVP then treatment is similar to that of primary open angle glaucoma (POAG)<ref>Stock RA, Fenandes NL, Pastro NL, de Oliveira RS, Bonamigo EL. Idiopathic dilated episcleral vessels (Radius-Maumenee syndrome): case report. ''Arq Bras Oftalmol. ''2013;76(1):45-47.</ref>.  
  
 
== Medical therapy  ==
 
== Medical therapy  ==
 
+
Medical therapy is aimed at decreasing aqueous humor production and increasing uveoscleral outflow. Medications that enhance outflow through the conventional pathway are not as effective<ref name=":3" />. Beta blockers and carbonic anhydrase inhibitors are favored in treatment of elevated EVP. Given its action on the arterial vasculature, Apraclonidine may be considered as it decreases blood flow to the eye<ref>Mantzioros N, Weinreb RN. Apraclonidine reduces intraocular pressure in eyes with increased episcleral venous pressure. ''Journal of Glaucoma ''1992;1(1):42-43.</ref>.
Medical management of elevated IOP and secondary glaucoma due to elevatedEVP includes inhibiting aqueous production via beta-blockers and carbonic anhydrase inhibitor. Apraclonidine may also be considered due to its arterial vasoconstriction effects leading to less blood flow to the eye.<ref>Mantzioros N, Weinreb RN. Apraclonidine reduces intraocular pressure in eyes with increased episcleral venous pressure. Journal of Glaucoma. 1992 Apr 1(1):42-3.    </ref>  
 
  
 
== Surgery  ==
 
== Surgery  ==
  
Surgical intervention should be considered in cases that have not responded first to more conservative efforts. According to several case reports in the literature, uveal effusion-like syndromes have complicated trabeculectomies in elevated EVP and some authors recommend sclerotomies with filtering surgery.<ref name=":1" /><ref>Bhagat N, Lim JI, Minckler DS, Green RL. Posterior uveal effusion syndrome after trabeculectomy in an eye with ocular venous congestion. British Journal of Ophthalmology. 2004 Jan 1;88(1):153-4.    </ref> Laser trabeculoplasty has shown not to be beneficial.<ref name=":0" /> One case report recommends performing a "tight" trabeculectomy with multiple releasable sutures to titrate the IOP gradually and prevent anterior chamber shallowing during surgery.<ref>Pradhan ZS, Kuruvilla A, Jacob P. Surgical management of glaucoma secondary to idiopathic elevated episcleral venous pressure. Oman Journal of Ophthalmology. 2015 May;8(2):120.</ref>
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Surgical therapy should be considered if patients are refractory to medical therapy. Again, aim should be to bypass the trabecular outflow, therefore selective laser trabeculoplasty (SLT) and micro-pulse laser trabeculoplasty (MLT) are not recommended<ref name=":3" />. Trabeculectomy and sclerotomy are appropriate surgical options. Eyes with elevated EVP have been reported to be at higher risk for uveal effusion syndrome<ref name=":0" /><ref>Bellows AR, Chylack LT, Epstein DL, Hutchinson BT. Choroidal effusion during glaucoma surgery in patients with prominent episcleral vessels ''Arch Ophthalmol ''1979;97(3):493-497.</ref>. Therefore, special consideration is needed to prevent hypotony during surgery. Prophylactic sclerotomies or scleral windows may be necessary<ref name=":4" />. One case recommends a surgical technique where a tight trabeculectomy with multiple adjustable sutures, the sutures can then be used to titrate the IOP gradually and therefore prevent acute shallowing of the anterior chamber intraoperatively<ref>Pradhan ZS, Kuruvilla A, Jacob P. Surgical management of glaucoma secondary to idiopathic elevated episcleral venous pressure. ''Oman Journal of Ophthalmology. ''2015;8(2):120.    </ref>. Other reports suggest maintaining the anterior chamber with injection of balance salt solution and viscoelastic, in addition to adjustable suture placement on the scleral flap<ref name=":3" />. Medical management post operatively can include use of cycloplegic agents and glucocorticoids to reduce inflammation<ref name=":3" />.
 
 
== Follow up  ==
 
  
Follow up of elevated EVP may depend upon the underlying cause, but otherwise is similar to that of other glaucomatous conditions. Patients should undergo routine follow-up assessing visual acuity, IOP, gonioscopy, visual fields, OCT, and DFE and EVP with appropriate referral as necessary for any additional underlying condition.  
+
== Complications  ==
 +
The major complication for untreated elevated EVP is development of secondary open angle glaucoma. Elevated EVP can also lead to acute angle closure glaucoma as suprachoroidal hemorrhage with subsequent forward displacement of the lens-iris diaphragm<ref>Buus DR, David TT, Parish RK. Spontaneous carotid cavernous fistula presenting with acute angle closure glaucoma ''Arch Ophthalmol. ''1989;107(4):596-597.</ref><ref>Fourman S. Acute closed angle glaucoma after arteriorvenous fistulas. ''Am J Ophthalmol. ''1989;107(2):156-159.    </ref>. Rarely, neovascular glaucoma can occur as a result of ocular ischemia<ref>Spencer WH, Thompson HS, Hoyt WF. Ischemic ocular necrosis from carotid-cavernous fistula. Pathology of stagnant anoxic inflammation in orbital and ocular tissues ''Br J Ophthalmol. ''1973;57(3):145.</ref>.  
  
== Complications  ==
+
== Follow Up  ==
  
A major complication of untreated elevated EVP is secondary open angle glaucoma. Elevated EVP can also lead to acute angle-closure glaucoma because venous stasis in the vortex veins can cause serous choroidal detachment or suprachoroidal hemorrhage leading to the forward displacement of the lens-iris diaphragm.<ref>Buus DR, David TT, Parrish RK. Spontaneous carotid cavernous fistula presenting with acute angle closure glaucoma. Archives of Ophthalmology. 1989 Apr 1;107(4):596-7.    </ref><ref>Fourman S. Acute closed-angle glaucoma after arteriovenous fistulas. American Journal of Ophthalmology. 1989 Feb 28;107(2):156-9.    </ref> Neovascular glaucoma has also been reported as a complication of elevated EVP once arterial blood flow has met enough IOP resistance to cause ocular ischemia.<ref>Spencer WH, Thompson HS, Hoyt WF. Ischemic ocular necrosis from carotid-cavernous fistula. Pathology of stagnant anoxic inflammation in orbital and ocular tissues. The British Journal of Ophthalmology. 1973 Mar;57(3):145.    </ref>
+
Follow up for these cases varies depending on the underlying etiology and IOP.  If following for secondary open angle glaucoma, frequent follow up is needed with routine IOP checks, gonioscopy, OCT and visual fields to monitor and prevent glaucomatous progression.    
  
 
= References  =
 
= References  =

Latest revision as of 09:59, January 26, 2021


Elevated Episcleral Venous Pressure (EVP)


Disease Entity

Elevated episcleral venous pressure (EVP) is a clinical finding which may be associated with elevated intraocular pressure (IOP) and glaucoma if left chronically untreated. In many cases the diagnosis is secondary to an underlying etiology, however it can also be idiopathic if all other causes are excluded. The idiopathic form can be familial or sporadic. In German literature idiopathic elevated EVP leading to secondary open angle glaucoma has been termed Radius-Maumenee Syndrome[1].

Pathophysiology

Based on the Goldmann equation, intraocular pressure (IOP) is the rate of aqueous humor production divided by the facility of outflow plus EVP[2]. The average EVP ranges from 8-10 mmHg[3], although can transiently change based on head positioning[4]. In the acute setting, there is a linear relationship and 1 mmHg rise in EVP correlates to a 1 mmHg rise in IOP[5]. However, this relationship is not as well understood in chronic cases.

In the conventional drainage pathway, aqueous humor flows through the efferent channels of the canal of Schlemm and then through the anterior ciliary venous circulation before converging with the episcleral venous plexus at Tenon’s capsule and the conjunctiva. Given the paucity of capillary networks in episcleral vessels, arteriovenous vasculature anastomosis predominate[2]. The aqueous in the episcleral venous plexus will then drain into the superior ophthalmic vein and enters the cavernous sinus above the annulus of Zinn, before flowing into the internal jugular vein and into the right atrium via the superior vena cava[6][7]. Any obstruction along this pathway may cause elevated EVP.

If there is increased venous pressure downstream to the episcleral anastomoses, then there is subsequent decrease in outflow of blood from the orbit and aqueous. Thus, in chronic cases, elevated EVP can cause blood reflux into Schlemm’s canal. This can subsequently raise IOP chronically, which can lead to glaucomatous damage due to secondary open angle glaucoma[8].

Etiology

Etiologies can range from venous obstruction to arteriovenous anomalies and can be acute or chronic in nature. It is important to elicit the timing of any trauma and do a full review of systems, including any previous infectious exposures, to rule out life or vision threatening causes of elevated EVP.

Venous Obstruction

Arteriovenous Anomalies

Idiopathic

Retrobulbar Tumor

Orbital Amyloidosis

Thyroid Ophthalmopathy 

Jugular Vein Obstruction

Congestive Heart Failure

Thrombosis of cavernous sinus or orbital vein

Vasculitis involving episcleral or orbital vein

Superior Vena Cava Syndrome (Mediastinal Tumor)

Carotid-Cavernous Sinus Fistula (acute vs. chronic)

Dural

Orbital Varix

Sturge-Weber Syndrome

Orbital-meningeal shunts

Carotid-jugular shunts

Sporadic

Familial

Risk Factors

Any history of head trauma is a risk factor for developing a carotid cavernous sinus, dural fistula or other arteriovenous anomaly which can lead to the development of elevated EVP.

Diagnosis

History

Typically, when patients present for evaluation of elevated EVP it is due to chronic eye redness that has not responded to previous treatment and often is misdiagnosed as chronic conjunctivitis[5]. They are usually unaware of their condition or underlying cause and typically do no describe pain or irritation. It is important to ask about recent trauma, specifically craniofacial, that can suggest a carotid cavernous sinus (high flow) or dural (low flow) fistula[5][9]. A complete past medical history should be obtained to rule out etiologies that may cause venous obstruction, including but not limited to hyperthyroidism, amyloidosis, congestive heart failure, hypercoagulable states, vasculitis, superior vena cava syndrome and Sturge-Weber Syndrome.

Physical examination

Clinical exam is the gold standard for diagnosing elevated EVP. Typically, on physical examination, the episclera is injected and demonstrates the pathognomonic corkscrew episcleral vessels without inflammation (Figure 1). It is important to perform gonioscopy, which can show an open angle with blood reflux in Schlemm’s canal or hyalinization of the wall of Schlemm’s canal due to chronic accumulation of blood[10]. Other signs include chemosis, proptosis and the presence of an orbital bruit, however these are specific signs for elevated EVP[10]. If the elevated EVP is secondary to a carotid-cavernous fistula, then pulsatile exophthalmos can sometimes be seen[11]. Intraocular pressure (IOP) can often times be elevated in the affected eye. Ancillary testing would include a optic coherence tomography (OCT) scan and Humphrey Visual Field testing to assess for glaucomatous changes.

Fig 1. Corkscrew vessels in elevated episcleral venous pressure.

Differential Diagnosis:

  • Episcleritis
  • Scleritis
  • Conjunctivitis
  • Ataxia Telangiectasia
  • Acute Closed Angle Glaucoma
  • Rosacea
  • Episcleral Nodule
  • Corneal lesion near limbus
  • Foreign body
  • Herpetic Keratitis
  • Uveal Neoplasm
  • Polycythemia vera
  • Leukemia[12]

Diagnostic procedures

A complete workout to rule out underlying etiology should be done when elevated EVP is suspected. In the setting of detecting an arteriovenous fistula, cerebral angiography is the gold standard, however orbital Doppler ultrasound is a non-invasive method which can confirm dilation of the superior ophthalmic vein[7]. Other modalities for diagnosis include orbital ultrasound, ultrasound biomicroscopy (UBM), computerized axial tomography and magnetic resonance imaging.

There are diagnostic modalities that measure EVP however are not routinely used in clinical practice. Direct cannulation is a direct method and can be done with the complete occlusion or partial vessel occlusion method; this is the most accurate test. Indirect methods include the venomanometer pressure chamber, torsion balance and air jet. Of the indirect methods the venomanometer is the most accurate.

Management

The aim of management should revolve around first treating the primary underlying etiology. If no etiology is determined for the elevated EVP then treatment is similar to that of primary open angle glaucoma (POAG)[13].

Medical therapy

Medical therapy is aimed at decreasing aqueous humor production and increasing uveoscleral outflow. Medications that enhance outflow through the conventional pathway are not as effective[7]. Beta blockers and carbonic anhydrase inhibitors are favored in treatment of elevated EVP. Given its action on the arterial vasculature, Apraclonidine may be considered as it decreases blood flow to the eye[14].

Surgery

Surgical therapy should be considered if patients are refractory to medical therapy. Again, aim should be to bypass the trabecular outflow, therefore selective laser trabeculoplasty (SLT) and micro-pulse laser trabeculoplasty (MLT) are not recommended[7]. Trabeculectomy and sclerotomy are appropriate surgical options. Eyes with elevated EVP have been reported to be at higher risk for uveal effusion syndrome[1][15]. Therefore, special consideration is needed to prevent hypotony during surgery. Prophylactic sclerotomies or scleral windows may be necessary[9]. One case recommends a surgical technique where a tight trabeculectomy with multiple adjustable sutures, the sutures can then be used to titrate the IOP gradually and therefore prevent acute shallowing of the anterior chamber intraoperatively[16]. Other reports suggest maintaining the anterior chamber with injection of balance salt solution and viscoelastic, in addition to adjustable suture placement on the scleral flap[7]. Medical management post operatively can include use of cycloplegic agents and glucocorticoids to reduce inflammation[7].

Complications

The major complication for untreated elevated EVP is development of secondary open angle glaucoma. Elevated EVP can also lead to acute angle closure glaucoma as suprachoroidal hemorrhage with subsequent forward displacement of the lens-iris diaphragm[17][18]. Rarely, neovascular glaucoma can occur as a result of ocular ischemia[19].  

Follow Up

Follow up for these cases varies depending on the underlying etiology and IOP. If following for secondary open angle glaucoma, frequent follow up is needed with routine IOP checks, gonioscopy, OCT and visual fields to monitor and prevent glaucomatous progression.    

References

  1. 1.0 1.1 Rhee DJ, Gupta M, Moncavage MB, Moster ML, Moster MR. Idiopathic elevated episcleral venous pressure and open angel glaucoma. Br J Ophthalmol. 2009;93(2):231-234.    
  2. 2.0 2.1 Moster M, Ichpujani P. Episcleral venous pressure, and glaucoma. . Journal of Current Glaucoma Practice 1996;3:1143-1155    
  3. Allingham RR, Damji KF, Freedman SF, Moroi SE, Rhee DJ, Shields MB. Shields textbook of Glaucoma 2012.    
  4. Arora N, McLaren JW, Hodge DO, Sit AJ. Effect of Body Position on Episcleral Venous Pressure in Healthy Patients. Invest Ophthalmol Vis Sci. 2017;58(12):5151-5156.    
  5. 5.0 5.1 5.2 Cioffi GA, Durcan FJ, Girkin CA. Basic and Clinical Science Course: Glaucoma. San Francisco: American Academy of Ophthalmology. 2013;26.    
  6. Higginbotham EJ. Glaucoma associated with increased episcleral venous pressure. Philadelphia WB Saunders 2000.    
  7. 7.0 7.1 7.2 7.3 7.4 7.5 Rong X, Li M. Advanced glaucoma secondary to bilateral idiopathic dilated episcleral veins - a case report BMC Ophthalmology 2018;18:207.    
  8. Minas TF, Podos SM. Familial glaucoma associated with elevated episcleral venous pressure. Archives of Ophthalmology 1980;80(1):202-208.
  9. 9.0 9.1 Girkin CA, Bhorade AM, Crowton JG, et al. Glaucoma United States of America 2018.    
  10. 10.0 10.1 Roll P, Benedikt O. Dilatation and tortuousity of episcleral vessels in open angle glaucoma II. Electron microscopy study of the trabecular meshwork Klin Monatsbl Augenheikd. 1980;176:297-301.
  11. Heichel J, Hammer T, Solymosi L, Brandt S, Winter I. Pressure-Lowering Effect of Fistula Occlusion in a Patient with Secondary Glaucoma due to an Intracranial Arteriovenous Fistula. Ophthalmology and Therapy. 2015;4(2):135-141.
  12. Bagheri N, Wajda BN, Calvo CM, Durrani AK. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease Philadelphia Lippincott Williams & Wilkins 2017.    
  13. Stock RA, Fenandes NL, Pastro NL, de Oliveira RS, Bonamigo EL. Idiopathic dilated episcleral vessels (Radius-Maumenee syndrome): case report. Arq Bras Oftalmol. 2013;76(1):45-47.
  14. Mantzioros N, Weinreb RN. Apraclonidine reduces intraocular pressure in eyes with increased episcleral venous pressure. Journal of Glaucoma 1992;1(1):42-43.
  15. Bellows AR, Chylack LT, Epstein DL, Hutchinson BT. Choroidal effusion during glaucoma surgery in patients with prominent episcleral vessels Arch Ophthalmol 1979;97(3):493-497.
  16. Pradhan ZS, Kuruvilla A, Jacob P. Surgical management of glaucoma secondary to idiopathic elevated episcleral venous pressure. Oman Journal of Ophthalmology. 2015;8(2):120.    
  17. Buus DR, David TT, Parish RK. Spontaneous carotid cavernous fistula presenting with acute angle closure glaucoma Arch Ophthalmol. 1989;107(4):596-597.
  18. Fourman S. Acute closed angle glaucoma after arteriorvenous fistulas. Am J Ophthalmol. 1989;107(2):156-159.    
  19. Spencer WH, Thompson HS, Hoyt WF. Ischemic ocular necrosis from carotid-cavernous fistula. Pathology of stagnant anoxic inflammation in orbital and ocular tissues Br J Ophthalmol. 1973;57(3):145.