Advances in Vitreoretinal Surgery

Educational Objectives

The goals of this program areto present advances in vitreoretinal surgery. After hearing and assimilating this program, the clinician will be better able to:

1. Recognize how advances in vitreoretinal surgery affect the types of patients undergoing surgery and the anesthetic options to be used.

2. Describe advanced instrumentation and procedures now being used in surgery for various vitreoretinal conditions.

3. Manage patients with severe systemic disease who are undergoing vitreoretinal surgery.

Summary

Consequences of advances: sicker patients now candidates for retinal surgery; most retina surgeons no longer use general anesthesia, except with children, mentally challenged patients, or those with language barriers or central nervous system (CNS) problems

Advances: smaller gauge surgery, ie, 25-gauge instruments; improved vitrectomy machines; refined instrumentation; result in more precise, accurate, and faster surgery on eyes with more advanced conditions (eg, patients with diabetes, advanced retinopathy, or advanced microvascular, renal, and cardiac disease)

Vitreous: clear tissue; 98% to 99% water; also contains collagen and hyaluronic acid; produced by nonpigmented ciliary body derived from embryonic mesenchymal cells; contains hyalocytes that make hyaluronic acid and phagocytes that clear cellular debris

Abnormalities: opacities — can occur because of hemorrhage or amyloid in patient with systemic amyloidosis; posterior vitreous detachments may occur in patients >50 yr of age; vitreomacular adhesions cause pulling on retina; may lead to formation cysts or macular hole requiring surgery; injection of ocriplasmin (Jetrea) promotes release of traction and closure of hole in ≈60% of cases; retinal vascular disease, eg, diabetes, vein occlusion, can cause bleeding or tractional retinal detachment requiring surgery; inflammatory disease can cause growth of membranes; tears and retinal detachments

Retinal surgery: introduced in 1960s; open-sky techniques developed to remove prolapsed vitreous during cataract surgery; procedure required removal of cornea; closed pars plana vitrectomy — eliminated need to remove cornea; allowed pressurizing of eye; closed system with normal intraocular pressure reduced risk for hypotony, bleeding, and infection; instrumentation — VISC instrument developed to provide illumination and remove vitreous; 3-port system (Ocutome) developed in 1972; guillotine cutter eliminated problem of vitreous winding around instrument; Accurus introduced in 1990s; by 2000, 25-gauge instruments appeared

Vitrectomy procedure: removes defective vitreous and adhesions to retina and replaces fluid; 25-gauge ports allow infusion of fluid into eye; 2 other ports (usually at 10:00 and 2:00 o’clock) used to gain access for illumination, suction, and cutting

Machine options: Constellation and Stellaris; allow fine control of aspiration and cutting right up to retina and cut membranes without engaging it; machines also replace intraocular fluid during procedure to maintain pressure (usually ≈20 mm Hg); possible to increase pressure to 50 or 60 mm Hg transiently to tamponade bleeding; cannulas color-coded to match ports on machine; illumination — xenon light sources and light picks provide excellent illumination of entire eye; cutting speed — previously operated at 600 cuts/min; now, 5,000 cuts/min achieved; produces little traction on retina; allows dissection of membranes and preretinal tissues and shaving of vitreous off detached retinas; suturing — cannulas remain in eye without suturing; not necessary to dissect conjunctiva off; 25-gauge holes self-seal at end of case; speaker prefers to suture holes in cases with gas or oil in eye to prevent leakage; other features — 25-gauge hole corresponds to 0.5 mm; 27-gauge (0.4 mm) instruments in development; in 25 plus cutter, hole closer to end to allow closer access to retina, and fluidics make this safer; visualization of retina better; wide-angle viewing systems provide 130° view of retina; chandelier lighting through port near pars plana region provides hands-free illumination of inside of eye to allow bimanual surgery

Adjuvants: dyes — include isocyanine green (ICG), brilliant blue, or trypan blue to stain internal limiting membrane to be peeled when fixing macular holes of certain size or chronicity; heavy fluid — holds down retina and forces any fluid underneath to come out; increases rate at which air-fluid exchange performed (now <2 min); silicon oil — infused into eye instead of gas

Epiretinal membrane example: causes whitening on surface of retina; optical coherence tomography (OCT) reveals membrane pulling on retina; 20% of cases require surgery; vessels sometimes entrenched; speaker peels if vision 20/40 or worse; patient required to remain absolutely immobile but not asleep; after removal of membrane, vision significantly improves

Macular cyst example: caused by traction; may evolve into macular hole; <5% of holes close without surgery; vitrectomy with gas recommended; make sure nitrous not on if gas used in patient under general anesthesia; if gas bubble inserted into eye, subsequent surgeries under general anesthesia can cause diffusion of gas into eye and problems with pressure and concentration

Macula-on retinal detachment example: necessary to find and seal holes and relieve pressure; patient immobility critical during surgery; buckle used in some eyes; necessary to isolate muscles for buckle, but pulling on muscle may cause bradycardia; treat with atropine

Trauma example: patients require general anesthesia; retrobulbar could cause extrusion of contents because of pressure; patient must not strain, cough, or buck during surgery (extrusion of intraocular contents may occur); possible challenges include intoxication, illicit drug use, trauma to CNS, or full stomach; severe extrusion not possible to correct; caution patient against Valsalva maneuver after surgery because of potential for bleeding

Retinal vascular diseases: patients with diabetes require removal of media opacities, surface membranes, laser treatment around holes, treatment of areas of ischemia, and tamponade of holes with gas bubble or oil; case example — patient had hypertension (HTN) so increased risk for bleeding when cutting membranes; important to reduce HTN as much as possible (eg, <140 mm Hg systolic); second case example — patient had membrane on top of retina ie, neovascularization of optic disc (NVD) and neovascularization elsewhere (NVE); speaker used 23-gauge instrument to go underneath membrane, cut it, and aspirate blood without cutting underlying retina; bleeding may produce clot that surgeon can peel off; safety of procedure depends on hemodynamic stability; third case example — patient had lymphoma and needed biopsy of retina; necessary to go into lesion of retina; again, patient immobility critical during procedure

Case history A: patient with severe diabetes, HTN, renal insufficiency, mildly uncontrolled diabetes, and proliferative diabetic retinopathy with traction retinal detachment; speaker administered sedation and retrobulbar block; during surgery, patient became nauseated; speaker removed instruments through cannulas; patient vomited solid food despite NPO before surgery; after stabilizing patient, speaker continued surgery, but vomiting commenced again; patient had gastroparesis; before surgery on fellow eye, patient limited to liquids for 2 days, NPO for 1 day

Case history B: patient had diabetes and severe proliferative retinopathy in both eyes; at surgery, patient had heart rate of 45 beats/min; electrocardiography (ECG) revealed heart block; cardiologists implanted temporary pacemaker; speaker completed eye procedure; patient received permanent pacemaker

Impacts of advances in vitreoretinal surgery on anesthesiologists: sicker patients present for clearance and surgery; shorter operating times result in more cases and higher throughput; fewer patients require general anesthesia

Questions and answers: entry of air into central circulation — if cannula dislodged, choroid would bulge out visibly before air entered; if patient has pit in optic nerve, injected air or oil can go through pit into CNS; entry of air into vessel unlikely unless eye became very hypotonous and collapsed, creating negative vacuum; general anesthesia — some surgeons feel more comfortable using general anesthesia while training to allow free discussion with trainee; does not affect choroidal hemorrhage; laryngeal mask airway (LMA) acceptable; speaker does not request paralysis as long as patient unlikely to have “hemiballistic” movements; timing of surgery for retinal detachment — for macula-on, literature supports waiting ≤24 hr before surgery if necessary; possible to wait 1 to 3 days for macula-off; anesthesia for buckles — speaker uses local unless patient has dementia or limited ability to understand; retrobulbar block adequate if enough volume given; speaker recommends applying topical block, prepping patient for surgery, cutting down conjunctiva, inserting cannula, and delivering up to 7 mL (minimum of 4-5 mL); extent of movement — speaker usually requires almost absolute akinesia during membrane peel or repair of retinal detachment; can tolerate slight movement during removal of vitreous hemorrhage or amyloid; speaker adds block if movement returns during procedure

Readings

Suggested Reading

Barlas S: FDA strategies to prevent and respond to drug shortages: finding a better way to predict and prevent company closures. P T 38:261, 2013; Becker DJ et al: Impact of oncology drug shortages on patient therapy: unplanned treatment changes. J Oncol Pract 9:e122, 2013; Centers for Disease Control and Prevention (CDC): Impact of a shortage of first-line antituberculosis medication on tuberculosis control — United States, 2012-2013. MMWR Morb Mortal Wkly Rep 24:62, 2013; De Oliveira GS Jr et al: Shortage of perioperative drugs: implications for anesthesia practice and patient safety. Anesth Analg 113:1429, 2011; Elzawawy AM, Kerr DJ: Variation in the availability of cancer drug generics in the United States of America. Ann Oncol 24 (Suppl 5): v17, 2013; Hall R et al: Drug shortages in Canadian anesthesia: a national survey. Can J Anaesth 60:359, 2013; Jensen V, Rappaport BA: The reality of drug shortages — the case of the injectable agent propofol. N Engl J Med 363:806, 2010; McCannel CA et al: Snoring is associated with unexpected patient head movement during monitored anesthesia care vitreoretinal surgery. Retina 32:1324, 2012; McLaughlin M et al: Effects on patient care caused by drug shortages: a survey. J Manag Care Pharm 19:783, 2013; Pacella E et al: Efficacy and safety of 0.5% levobupivacaine versus 0.5% bupivacaine for peribulbar anesthesia. Clin Ophthalmol 7:927, 2013; Recchia FM et al: Small-gauge pars plana vitrectomy: a report by the American Academy of Ophthalmology. Ophthalmology 117:1851, 2010; Rush RB et al: Postoperative macular hole formation after vitrectomy with internal limiting membrane peeling for the treatment of epiretinal membrane. Retina Nov 8, 2013 [Epub ahead of print]; Steel DH, Charles S: Vitrectomy fluidics. Ophthalmologica 226 (Suppl 1):27, 2011.

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, Dr. Lim and the planning committee reported nothing to disclose. In this lecture, Dr. Lim presents information that is related to the off-label or investigational use of a therapy, product, or device.

Acknowledgements

Dr. Lim spoke at the 2013 Annual Meeting of the Ophthalmic Anesthesia Society, held September 20-22, 2013, in Chicago, IL, and presented by the Ophthalmic Anesthesia Society (to learn more about CME programs at the Ophthalmic Anesthesia Society, please visit eyeanesthesia.org). The Audio-Digest Foundation thanks Dr. Lim and the Ophthalmic Anesthesia Society for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

OP520202

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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