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SURGICAL EMBOLECTOMY FOR FOVEA-THREATENING ACUTE RETINAL ARTERY OCCLUSION

Almeida, David R.P. MD, MBA, PhD; Mammo, Zaid MD; Chin, Eric K. MD; Mahajan, Vinit B. MD, PhD

RETINAL Cases & Brief Reports: Fall 2016 - Volume 10 - Issue 4 - p 331–333
doi: 10.1097/ICB.0000000000000257
Case Report

Purpose: To describe a technique of surgical intraocular embolectomy in patients with acute fovea-threatening branch retinal artery occlusion.

Methods: Pars plana vitrectomy with embolectomy involving embolus isolation, dissection, and removal in patients with an acute fovea-threatening arterial occlusion without a patent cilioretinal artery.

Results: The surgical technique involves a core vitrectomy. The blocked artery is incised using a microvitreoretinal blade, and microsurgical forceps are used to retrieve the embolus. No significant complications were noted. The study technique offers an excellent safety profile and minimizes the risk of vitreous hemorrhage by carefully dissecting the vascular adventitial sheath and isolating the embolus.

Conclusion: Surgical embolectomy is a viable technique for patients with acute fovea-threatening arterial occlusions without patent cilioretinal artery. Careful dissection and retrieval of the embolus minimizes the risk of vitreous hemorrhage, which is an important improvement in previous techniques for management of acute retinal arterial occlusions.

The authors describe a surgical technique to facilitate the exposure and retrieval of embolus in cases of fovea-threatening retinal artery occlusion without a patent cilioretinal artery. The authors include a number of surgical pearls based on our experience that may facilitate intraocular emboli retrieval and minimize the common complication of vitreous hemorrhage associated with retinal embolectomy.

*VitreoRetinal Surgery, PA, Minneapolis, Minnesota;

Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia;

Retina Consultants of Southern California, Riverside, California;

§Vitreoretinal Service, Departments of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa; and

Omics Laboratory, Iowa City, Iowa.

Reprint requests: Vinit B. Mahajan, MD, PhD, Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242; e-mail: vinit-mahajan@uiowa.edu

None of the authors have any financial/conflicting interests to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (www.retinajournal.com).

D. R. P. Almeida and V. B. Mahajan had full access to all the data in the study and take full responsibility for the integrity of the data and the accuracy of the data analysis. All authors contributed to the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, and approval of the manuscript; and the decision to submit the manuscript for publication.

Full adherence to the Declaration of Helsinki and all Federal and State laws was observed.

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND), which permits downloading and sharing the work provided it is properly cited. The work cannot be changed in any way or used commercially.

Branch retinal arterial occlusion (BRAO) is a common clinical entity and has been reported to account for approximately 40% of all arterial occlusions.1,2 Displaced embolus is the most common etiology.3 Surgical embolectomy is a controversial therapy for arterial occlusions; however, in some cases where the fovea is threatened and no patent cilioretinal artery exists, embolectomy maybe the only realistically efficacious management available. Although visual acuity may remain intact in most patients, a subset of patients will have progressive and permanent visual decline and field deficits2; these patients are most likely to be ones without cilioretinal arteries and BRAO that are close to the fovea. Given the lack of efficacy of noninvasive treatment options for arterial occlusions,4 surgical embolectomy is proposed as an alternative invasive option for fovea-threatening acute arterial occlusions.

We describe a surgical technique for the isolation and retrieval of an embolus in acute cases of fovea-threatening symptomatic BRAO. Our technique uses a pars plana vitrectomy approach to retrieve the arterial embolus under direct visualization. By carefully dissecting the overlying vitreous, retina, and vascular sheath, one is able to minimize the risk of vitreous hemorrhage, which has commonly plagued previous examples of retinal embolectomy.

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Surgical Technique

A standard three-port pars plana vitrectomy is performed. A press-on macular lens is used for high-magnification and enhanced stereopsis. Dilute 50% intravitreal triamcinolone acetonide is injected into the vitreous cavity to induce a complete posterior vitreous detachment and aid in visualization and removal of any unopacified vitreous overlying the embolectomy site. Meticulous mechanical dissection of any remnant vitreous strands overlying the occlusion site is necessary for subsequent successful dissection of the vascular adventitial sheath. Once all vitreous is removed from the embolus site, a 25-gauge microvitreoretinal blade is used to carefully dissect the vascular sheath with longitudinal incisions along the plane of blood vessel flow. This dissection is performed until the wall of the arteriole is carefully and completely (i.e., full thickness) incised; during this part of the procedure, the infusion pressure should be temporarily elevated to approximately 50 mmHg to 60 mmHg to minimize risk of hemorrhage. Intraocular end-gripping forceps are then used to grasp the exposed embolus, through the arteriole lumen, and remove the embolus from the eye.

It should be noted that, if significant traction is encountered when trying to remove the embolus with forceps, a small retinal hemorrhage maybe encountered, which indicates that the adventitial sheath has not been fully dissected and the arteriolar lumen not yet incised. To overcome this, reintroduce the microvitreoretinal blade and further dissect and expose the embolus. With better exposure and minimal traction, the embolus can then be retrieved using microsurgical forceps. Careful dissection of overlying vitreous, and the vascular sheath, is key to exposing the embolus without the occurrence of vitreous hemorrhage, which severely limits ability to visualize the subsequent embolus removal. The technique, in its entirety, is provided in video format (see Video, Supplemental Digital Content 1, http://links.lww.com/ICB/A16).

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Discussion

In this report, we describe a surgical embolectomy technique for cases of acute fovea-threatening branch arterial occlusions. Surgical embolectomy is a controversial technique that maybe of limited benefit in cases of stationary peripheral BRAO. However, when a branch arterial occlusion threatens the fovea, and there is no patent cilioretinal artery to offer collateral blood flow to the fovea, then surgical embolectomy provides a viable intervention to help prevent possible compromise of the central macula.

Given the acute ischemic insult of arterial occlusions, prompt reperfusion is paramount to maximize visual benefit.3 Although largely safe, noninvasive treatment options—such as lowering the intraocular pressure or hyperbaric oxygen—have been found to lack efficacy.4 More invasive options, including intraarterial tissue plasminogen activator, similarly offered no treatment benefit with significant adverse events.5 Translumenal Nd:YAG laser has been used to photodisrupt obstructive arterial emboli with promising visual outcomes; yet, significant vitreous hemorrhage, collateral tissue damage, and the potential for emboli fragmentation remain.6–8

Surgical embolectomy was successfully attempted by Peyman and Gremillion in 1990.9 At the time of writing this report, a total of 12 cases have undergone surgical embolectomy in the literature9–13; however, because of the common complication of vitreous hemorrhage present in all previously published cases, no clear surgical technique appears in the literature. We believe our technique is succinct in its ability to prevent intraoperative vitreous hemorrhage by means of careful vitreous removal and vascular sheath dissection along the plane of blood vessel flow; we have performed this technique three times without any incidence of vitreous hemorrhage.

A number of points should be considered with regards to our surgical embolectomy technique; first and foremost, case selection is critical, and only patients with fovea-threatening BRAO without a patent cilioretinal artery should be considered. Second, the natural history and prognosis of branch and central retinal artery occlusions should be discussed preoperatively during the consent process, and only after a thorough discussion about the risks and benefits of the surgery, should appropriate consent be obtained and surgical embolectomy planned. Third, mechanical vitreous displacement facilitates precise vessel incision and minimizes traction, which prevents vessel rupture and vitreous hemorrhage during embolus retrieval that was present in all previously reported cases. Fourth, the initial vessel wall incision may need to be extended in almost all cases. A larger incision improves exposure and decreases the grasping force required to retrieve the embolus. Finally, intraocular pressure variations could cause either retrograde or anterograde embolus movement, an aspect that complicated the retrieval of the embolus in one report.12 We recommend using valved cannulas and maintaining a steady but elevated intraocular pressure during the vessel incision and embolus removal for optimal results.

This report describes the successful technique of embolus retrieval in acute cases of fovea-threatening BRAO with no occurrence of intraoperative vitreous hemorrhage. Careful preoperative clinical considerations such as patient consent and selection of only fovea-threatening cases without a patent cilioretinal artery are paramount to success. We provide a surgical video and a number of pearls to help vitreoretinal surgeons perform this procedure.

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References

1. Brown GC, Shields JA. Cilioretinal arteries and retinal arterial occlusion. Arch Ophthalmol 1979;97:84–92.
2. Hayreh SS, Podhajsky PA, Zimmerman MB. Retinal artery occlusion: associated systemic and ophthalmic abnormalities. Ophthalmology 2009;116:1928–1936.
3. Hayreh SS. Acute retinal arterial occlusive disorders. Prog Retin Eye Res 2011;30:359–394.
4. Fraser SG, Adams W. Interventions for acute non-arteritic central retinal artery occlusion. Cochrane Database Syst Rev 2009;CD001989.
5. Feltgen N, Neubauer A, Jurklies B, et al. Multicenter study of the European Assessment Group for Lysis in the Eye (EAGLE) for the treatment of central retinal artery occlusion: design issues and implications. EAGLE Study report no. 1: EAGLE Study report no. 1. Graefes Arch Clin Exp Ophthalmol 2006;244:950–956.
6. Mason JO III, Nixon PA, Albert MA Jr. Trans-luminal nd:YAG laser embolysis for branch retinal artery occlusion. Retina 2007;27:573–577.
7. Opremcak E, Rehmar AJ, Ridenour CD, et al. Restoration of retinal blood flow via translumenal Nd:YAG embolysis/embolectomy (TYL/E) for central and branch retinal artery occlusion. Retina 2008;28:226–235.
8. Hsu TK, Chen SJ, Lei J, et al. Embolus-induced branch retinal artery occlusion with a presenting best-corrected visual acuity of <6/12 and visual field defect: yag embolectomy safely restores arteriolar perfusion and/or visual function. Retin Cases Brief Rep 2013;7:210–216.
9. Peyman GA, Gremillion CM Jr. Surgical removal of a branch retinal artery embolus: a case report. Int Ophthalmol 1990;14:295–298.
10. Garcia-Arumi J, Martinez-Castillo V, Boixadera A, et al. Surgical embolus removal in retinal artery occlusion. Br J Ophthalmol 2006;90:1252–1255.
11. Brunner S, Binder S. Surgical embolus excision in retinal artery occlusion—two case reports. Acta Ophthalmol 2013;91:e652–e653.
12. Ramchandran RS, Fekrat S. Embolectomy for branch retinal arterial occlusion. Retin Cases Brief Rep 2010;4:116–119.
13. Matonti F, Hoffart L, Nadeau S, et al. Surgical embolectomy for central retinal artery occlusion. Can J Ophthalmol 2013;48:e25.
Keywords:

vitrectomy; retinal artery occlusion; embolectomy

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