Anesthesiologist's Manual of Surgical Procedures, 4th ed.

Ophthalmology

Ophthalmic Surgery

Eleonora M. Lad MD, PhD

Surgeon

Peter R. Egbert MD

Surgeon

Darius M. Moshfeghi MD

Surgeon

Richard A. Jaffe MD, PhD

Anesthesiologist

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Cataract Extraction with Intraocular Lens Insertion

Surgical Considerations

Description: Cataract–the leading cause of treatable blindness in the world–is defined as opacification of the crystalline lens. Cataract surgery is among the most common surgical procedures, with more than 1.3 million performed in the United States each year. Several approaches to cataract removal have evolved as a result of advances in both instrumentation and artificial intraocular lenses (IOL). Most modern cataract surgery is performed using the extracapsular technique, which involves removal of the crystalline lens through an opening made in the anterior lens capsule (known as a capsulectomy). Removal of the lens nucleus can then be accomplished intact, which requires an 8-10 mm corneal incision, or by phacoemulsification wherein ultrasound energy is used to fragment the lens, allowing aspiration of the lens material. The advantage to phacoemulsification is that the entire procedure can be performed through a much smaller, clear corneal incision (usually ~3 mm in length). With both approaches, the softer, more peripheral cortical lens material is then removed by aspiration, leaving the posterior capsular bag intact to support an IOL implant (Fig. 2-1). If the lens capsule is torn or is for any reason unable to support an IOL, the lens can be fixated with sutures in the posterior chamber (behind the iris), or an anterior chamber IOL can be placed in front of the iris. Presently, the most popular materials for IOL implants are polymethylmethacrylate, silicon, and acrylic. Only silicon and acrylic are foldable, which allows their insertion through a small corneal incision and, therefore, are the most commonly used. The wound is closed with nylon or Vicryl suture (9-0 or 10-0) to achieve a watertight seal, although when small incisions are used, the wounds are often self-sealing and do not require sutures.

Variant procedure or approaches: Intracapsular cataract extraction involves removal of the crystalline lens with its surrounding capsular bag intact. To accomplish this, the zonules that normally stabilize and center the lens must be broken, and a cryoprobe often is used to remove the lens from the eye through a large incision. This procedure is performed infrequently, given the superior visual outcomes of extracapsular techniques. It may be indicated in situations where capsular bag support has been compromised by either trauma or inherited disorders.

Usual preop diagnosis: Cataract

 

Figure 2-1. (A) Placement of intraocular lens into remaining capsular bag. (B) “In-the-bag” insertion.

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Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

2.8 mm peripheral cornea (phacoemulsification) or 8–10 mm (corneoscleral junction)

Special instrumentation

Surgical microscope; phacoemulsification machine

Antibiotics

Subconjunctival cefazolin (50–100 mg) or gentamicin (20–40 mg) or a topical fluoroquinolone

Surgical time

15–60 min

EBL

None

Postop Care

Possible eye patch/shield for 24 h, topical medications

Mortality

Rare

Morbidity

Posterior capsule rupture: 3.1%
Corneal edema: < 2%
Macular edema: 1–2%
Retinal detachment: < 1%
Choroidal hemorrhage: 0.3%
Endophthalmitis: < 0.2 %

Pain score

1–2

Patient Population Characteristics

Age range

3 mo–75 yr

Male:Female

1:1

Incidence

> 1,000,000/yr in the United States

Etiology

Congenital; metabolic; traumatic; senile; medication-induced (steroids)

Associated conditions

Systemic diseases of elderly patients–common; cardiovascular disease; diabetes; HTN
Patients may be on antiplatelet or anticoagulant therapy. It is generally accepted that these drugs do not need to be discontinued before cataract surgery (especially if INR ≥ 1.5)

Anesthetic Considerations

Cataract surgery is performed worldwide using various regional, local, or topical anesthetic techniques and agents and general anesthesia. At the 2002 Congress of the International Council of Ophthalmology in Sydney, Australia, it was reported that almost all cataract surgeries worldwide were performed using regional anesthesia. Surgeons performed just over half of the anesthetic procedures, whereas anesthetists performed the rest of the procedures. The most frequently employed techniques were the peribulbar block followed by topical anesthesia.

At the present time in the United States, cataract surgery is most commonly performed using only topical anesthetic agents (e.g., preservative-free 2–4% lidocaine, levobupivacaine 0.75%, ropivacaine 1%, oxybuprocaine 1%, or tetracaine 0.5%) to block trigeminal nerve endings in the cornea and conjunctiva. Iris and ciliary body anesthesia depend on local anesthetic penetration into the anterior chamber. Thus, in a few patients, there may be a need for supplemental anesthetic administration (e.g., intracameral, 1% lidocaine) as well as systemic analgesic and sedative drugs. Inadvertent eye and lid movement should be expected. Adverse reactions to topical anesthetics are extremely rare and typically allergic in nature. A recent prospective randomized double-blind series demonstrated that combining topical anesthesia with intracameral lidocaine anesthesia was safe and effective in phacoemulsification with intraocular lens implantation. This technique avoided potential sequelae of retrobulbar or peribulbar anesthesia for cataract surgery. However, patients undergoing cataract surgery using topical anesthesia reported greater intraoperative and postoperative discomfort than those given a sub-Tenon

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block. Use of intravenous sedation increased the incidence of adverse events as compared with topical anesthesia without sedation.

Anesthesia-trained personnel monitored most patients during cataract surgery, and the most commonly used local anesthetic was lidocaine. The anesthetic method associated with the lowest degree of pain, dissatisfaction, drowsiness, or nausea and vomiting was a regional block technique with administration of sedatives and diphenhydramine.

See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC (adult), p. 154, or for Pediatric Ophthalmic Surgery, p. 1175.

Suggested Readings

  1. Borazan M, Karalezli A, Akova YA, Algan C, Oto S: Comparative clinical trial of topical anaesthetic agents for cataract surgery with phacoemulsification: lidocaine 2% drops, levobupivacaine 0.75% drops, and ropivacaine 1% drops. Eye2008; 22(3):425–9.
  2. Chuang LH, Yeung L, Ku WC, et al: Safety and efficacy of topical anesthesia combined with a lower concentration of intracameral lidocaine in phacoemulsification: paired human eye study. J Cataract Refract Surg2007; 33(2):293–6.
  3. Coelho RP, Weissheimer J, Romão E, et al: Pain induced by phacoemulsification without sedation using topical or peribulbar anesthesia. J Cataract Refract Surg2005; 31(2):385–8.
  4. Eichel R, Goldberg I: Anaesthesia techniques for cataract surgery: a survey of delegates to the Congress of the International Council of Ophthalmology, 2002. Clin Experiment Ophthalmol2005; 33(5):469–72.
  5. Eke T, Thompson JR: Serious complications of local anaesthesia for cataract surgery: a 1 year national survey in the United Kingdom. Br J Ophthalmol2007; 91(4):470–5.
  6. Ezra DG, Allan BD: Topical anaesthesia alone versus topical anaesthesia with intracameral lidocaine for phacoemulsification. Cochrane Database Syst Rev2007; 3:CD005276.
  7. Kallio H, Rosenberg PH: Advances in ophthalmic regional anaesthesia. Best Pract Res Clin Anaesthesiol2005; 19(2):215–27.
  8. Katz J, Feldman MA, Bass EB, et al: Injectable versus topical anesthesia for cataract surgery: Patient perceptions of pain and side effects. Ophthalmology2000; 107:2054–60.
  9. Navaleza JS, Pendse SJ, Blecher MH: Choosing anesthesia for cataract surgery. Ophthalmol Clin North Am2006; 19(2): 233–7.
  10. See Suggested Reading following Ophthalmic Surgery section, p. 171
  11. Srinivasan S, Fern AI, Selvaraj S, et al: Randomized double blind clinical trial comparing topical and sub-Tenon's anaesthesia in routine cataract surgery. Br J Anaesth2004; 93:683–6.
  12. Tan CS, Au Eong KG, Kumar CM: Visual experiences during cataract surgery: what anaesthesia providers should know. Eur J Anaesthesiol2005; 22(6):413–19.
  13. Vann MA, Ogunnaike BO, Joshi GP: Sedation and anesthesia care for ophthalmologic surgery during local/regional anesthesia. Anesthesiology2007; 107(3):502–8.

Corneal Transplant

Surgical Considerations

Description: Corneal transplantation (penetrating keratoplasty [PKP]) involves replacing a portion of the host cornea with tissue from a donor eye (allograft). The primary goals of this procedure are to restore both the integrity of the cornea and to establish a clear visual axis. The ideal death-to-preservation time of the donor cornea is < 18 h, and the donor cornea can be stored for up to 2 wks before transplantation. The procedure often begins with the placement of a scleral fixation ring (Flieringa ring), just beyond the corneoscleral junction, which is secured with 7-0 Vicryl sutures. This provides additional scleral support that is especially helpful in children or patients who have undergone previous cataract surgery. The donor corneal button is removed from the surrounding corneoscleral rim with a trephine and kept in storage medium until the recipient bed is prepared. The host cornea is then trephined in a previously marked central location, using either manual or vacuum-assist techniques. After the eye is opened, it is critical to avoid patient movement, coughing, bucking, or any Valsalva maneuvers to prevent expulsion of the intraocular contents through the wound. The size of the donor button is generally cut ~0.25 mm larger than the host bed. The donor cornea is then sutured into place with 10-0 nylon sutures, which can be accomplished using 16 interrupted sutures, running sutures, or a combination, depending on a number of factors unique to each patient. Great care is taken during manipulation of the allograft to avoid

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trauma to the inner surface of the graft, as damage to the endothelial cells in this location can result in primary graft failure.

Variant procedure or approaches: PKP may be combined with cataract extraction or exchange of a previously placed intraocular lens (IOL). Additionally, PKP may be combined withlimbal stem-cell transplantation (autograft from less injured eye) in cases where the most superficial corneal epithelial layer is unable to regenerate following damage (e.g., chemical burn injuries) to the limbal stem cells. Partial-thickness transplants, called lamellar keratoplasty, also can be performed in certain clinical situations.

Usual preop diagnosis: Persistent corneal edema; inherited corneal dystrophy; keratoconus; corneal scar

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Corneal

Special instrumentation

Surgical microscope

Unique considerations

Open-globe precautions: Avoid coughing, bucking, or Valsalva maneuvers to prevent expulsion of intraocular contents.

Antibiotics

Subconjunctival cefazolin (50–100 mg) or gentamicin (20–40 mg)

Surgical time

60–90 min

EBL

Minimal

Postop care

Patch/shield for 24 h, long-term topical immunosuppression to prevent graft rejection

Mortality

Rare

Morbidity

Graft rejection: ~5%
Suprachoroidal hemorrhage: < 1% (higher for MAC: ~4%)
Infection: < 1%

Pain score

2

Patient Population Characteristics

Age range

Any age

Male:Female

1:1

Incidence

> 40,000 cases/yr in the United States and Canada

Etiology

Corneal opacity or decompensation resulting from endothelial failure; inherited dystrophy; keratoconus; scarring related to trauma/chemical burn/infection

Associated conditions

Congenital malformations; sleep apnea; atopic disease/asthma; Down syndrome

Anesthetic Considerations

Corneal transplants commonly require GA or a retrobulbar/peribulbar block to prevent movement of the eyelids or extraocular muscles that could lead to distortion of the globe during the procedure. However, in patients with significant coagulopathy, a history of perforated corneal ulcers, severe systemic disease, or other conditions that make the use of these forms of anesthesia less preferable, PKP can be performed with topical anesthesia in cooperative patients.

See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC (adult), p. 154, or for Pediatric Ophthalmic Surgery, p. 1175.

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Suggested Readings

  1. Kallio H, Rosenberg PH: Advances in ophthalmic regional anaesthesia. Best Pract Res Clin Anaesthesiol2005; 19(2):215–27.
  2. Riddle HK Jr, Price MO, Price FW Jr: Topical anesthesia for penetrating keratoplasty. Cornea2004; 23(7):712–4.
  3. See Suggested Readings following Ophthalmic Surgery section, p. 171.
  4. Thompson RW Jr, Price MO, Bowers PJ, et al: Long-term graft survival after penetrating keratoplasty. Ophthalmology2003; 110:1396–1402.

Trabeculectomy

Surgical Considerations

Description: Glaucoma is a disorder characterized by progressive optic neuropathy in which elevated intraocular pressure (IOP) is the most modifiable risk factor. It is the second most common cause of blindness in the United States and accounts for more than 5.1 million cases of blindness throughout the world. Trabeculectomy (glaucoma filtration procedure) is the most common surgical procedure used to reduce IOP and is often undertaken only after medical therapy has failed. In trabeculectomy, a drainage fistula is created from the anterior chamber to the subconjunctival space, allowing aqueous humor to drain from the eye. (Normal anatomy relevant for aqueous fluid production is shown in Fig. 2-2). First, an incision is created in the conjunctiva and Tenon's layer, exposing the underlying bare sclera. A partial-thickness (4–5 mm) scleral flap, hinged at the limbus, is then created. Because scarring is the most common cause of surgical failure, antimetabolites, such as mitomycin-C or 5-fluorouracil, are often applied to the surgical site to slow or prevent fibroblast proliferation. Next, an incision into the anterior chamber is created at the base of the scleral flap and converted to a sclerotomy by removing an approximate 1 × 4 mm piece of corneoscleral tissue. To prevent the iris from entering the fistula as well as to protect against future angle closure, an iridectomy is performed, followed by closure of the overlying scleral flap with 10-0 nylon sutures. Before closure, it is important to avoid coughing, bucking, or Valsalva maneuvers, which might cause suprachoroidal hemorrhage or expulsion of intraocular content. The conjunctiva is then reapposed, using running 8-0 or 9-0 Vicryl suture.

 

Figure 2-2. Ocular anatomy concerned with control of IOP. (Reproduced with permission from Barash PG, Cullen BF, Stoelting RK, eds: Clinical Anesthesiology, 4th edition. Lippincott Williams & Wilkins, 2001.)

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Figure 2-3. Basic technique of inserting Molteno implant. Silicone tube is inserted into anterior chamber via needle track and is connected to a subconjunctival acrylic plate that is attached to the sclera near the equator. (Reproduced with permission from Shields MB: Textbook of Glaucoma, 4th edition. Williams & Wilkins, Philadelphia, 1998.)

Variant procedure or approaches: In patients for whom trabeculectomy has failed, a variety of drainage implants have been created to maintain the patency of the drainage fistula. These devices (e.g., Ahmed, Molteno, Krupin, Baerveldt) consist of plastic reservoirs that are placed in the sub-Tenon's space and are connected to a tube that enters the anterior chamber (Fig. 2-3). These devices differ in implant size and whether or not there is an internal valve to prevent excessive drainage. Long-term IOP reduction with drainage implants is not as successful as trabeculectomy.

In infants and children with congenital glaucoma (see Pediatric Ophthalmic Surgery, p. 1174), the anterior chamber angle, which normally allows outflow of aqueous, develops abnormally and often requires surgical intervention. Goniotomy (opening Schlemm's canal) is usually the initial procedure of choice. An alternative procedure is a trabeculotomy performed by exposing Schlemm's canal (the drainage system) in a corneoscleral cutdown. A trabeculotome is then threaded into this canal and is rotated, creating a tear in the trabecular meshwork and allowing direct communication between the anterior chamber and Schlemm's canal.

Usual preop diagnosis: Glaucoma

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Superior portion of eye

Special instrumentation

Surgical microscope

Unique considerations

Prevent coughing, bucking, Valsalva maneuvers while globe is open, to prevent expulsion of intraocular contents.

Antibiotics

Subconjunctival cefazolin (50–100 mg) or gentamicin (20–40 mg)

Surgical time

30–60 min

EBL

Minimal

Postop care

Patch/shield × 24 h; long-term topical immunosuppression to reduce scarring. Scleral flap
sutures can be cut with a laser postop to increase flow.

Mortality

Rare

Morbidity

Overfiltration causing hypotony
Leaking bleb
Fistula scarring
Infection

Pain score

1–2

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Patient Population Characteristics

Age range

Any age; more common in the elderly

Male:Female

1:1

Incidence

1.7% Caucasians; 5.6% African-Americans

Etiology

Cause of primary open angle unknown, but elevated IOP is the strongest risk factor. Many secondary causes, including angle closure, trauma, inflammation, neovascularization, and congenital abnormalities

Associated conditions

Diseases of the elderly, including cardiovascular disease, HTN, and diabetes. Children may have multiple congenital anomalies.

Anesthetic Considerations

Trabeculectomy is typically accomplished using sub-Tenon anesthesia, which allows monitoring of conjunctival mobility when selecting the surgical site. Alternatively, it can be done using topical anesthetics. GA is usually reserved for pediatric patients, patients unlikely or unable to cooperate during the procedure, or if low intraocular pressure from anesthesia is desirable.

Subconjunctival anesthesia at the bleb site may be associated with a poorer outcome, because it may stimulate fibroblasts to cause scarring due to hemorrhage and tissue damage. Peribulbar and retrobulbar injections in patients with advanced glaucoma may be associated with increased intraocular pressure, which can be prevented by decreasing anesthetic volumes and avoiding the use of orbital Honan balloons.

Topical and intracameral anesthesia are being increasingly employed for trabeculectomy to avoid injection pain and potential complications, such as conjunctival button holes and hemorrhage. However, topical agents have the following limitations: inferior duration and intensity of anesthetic effect and lack of ocular akinesia, which is necessary to prevent globe compression in patients with prominent eyelid squeezing. Topical gels are not ideal in trabeculectomy because they can interfere with the surgical site. Intracameral lidocaine as a supplement to topical anesthesia has the theoretical advantage of increasing depth of anterior chamber, but it poses the risk of damaging the phakic lens and excessive iridectomy enlargement. To avoid these possible complications, intracameral acetylcholine or topical pilocarpine can be used in conjunction with intracameral lidocaine.

See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC (adult), p. 154, or for Pediatric Ophthalmic Surgery, p. 1175.

Suggested Readings

  1. Carrillo MM, Buys YM, Faingold D, et al: Prospective study comparing lidocaine 2% jelly versus sub-Tenon's anaesthesia for trabeculectomy surgery. Br J Ophthalmol2004; 88(8):1004–7.
  2. Edmunds B, Bunce CV, Thompson JR, et al: Factors associated with success in first-time trabeculectomy for patients at low risk of failure with chronic open-angle glaucoma.Ophthalmology2004; 111:97–103.
  3. Jones E, Clarke J, Khaw PT: Recent advances in trabeculectomy technique. Curr Opin Ophthalmol2005; 16(2):107–13.
  4. Sauder G, Jonas JB: Topical anesthesia for penetrating trabeculectomy. Graefes Arch Clin Exp Ophthalmol2002; 240: 739–42.
  5. See Suggested Readings following Ophthalmic Surgery section, p. 171.
  6. Zabriskie NA, Ahmed IIK, Crandall AS, et al: A comparison of topical and retrobulbar anesthesia for trabeculectomy. J Glaucoma2002; 11:306–14.

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Ectropion Repair

Surgical Considerations

Description: Ectropion is a malposition of the eyelid, in which the lid margin is everted away from the globe. The surgical approach depends on the underlying anatomic abnormality, which can be congenital, involutional, cicatricial (scarring), or due to mechanical traction from masses or facial nerve palsy. A lateral tarsal strip procedure is often used, with the lateral canthal tendon first released by performing a lateral canthotomy and cantholysis of the crus (Fig. 2-4). A lateral portion of tarsus is then dissected free of overlying skin, muscle, and conjunctiva. This strip of tarsus is trimmed to the appropriate length and is secured to the periosteum of the lateral orbital rim with suture. Excess skin is removed and the defect is closed.

Variant procedure or approaches: Cicatricial ectropion from a contracting scar can sometimes be released with a Z-plasty incision that releases vertical skin tension. Alternatively, a full-thickness skin graft may be required and can be harvested from the upper lid or the postauricular or supraclavicular regions.

Usual preop diagnosis: Ectropion of the eyelid

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Lateral canthal region or area of scarring

Special instrumentation

Surgical loupes

Antibiotics

None intraop

Surgical time

0.5–1 h

EBL

Minimal

Postop care

Topical antibiotic ointment

Mortality

Rare

Morbidity

Lid malposition
Infection: Very rare

Pain score

1–2

Patient Population Characteristics

Age range

Any age

Male:Female

1:1

Incidence

Common

Etiology

Congenital; aging; malignancy; facial nerve palsy

Associated conditions

Systemic diseases of elderly patients common; cardiovascular disease; diabetes; HTN

Anesthetic Considerations

See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC (adult), p. 154, or for Pediatric Ophthalmic Surgery, p. 1175.

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Figure 2-4. In the tarsal strip procedure, the lower eyelid is incised laterally. The entire lower crus of the canthal tendon must be severed. (Redrawn with permission fromDuane's Clinical Ophthalmology, Vol. 5. Williams & Wilkins, Philadelphia, 2000.)

Suggested Reading

  1. See Suggested Reading following Ophthalmic Surgery section, p. 171.

Entropion Repair

Surgical Considerations

Description: Entropion is a condition characterized by an inward rotation of the eyelid margin. The surgical approach depends on the underlying anatomic abnormality, which can be congenital, spastic, involutional, or cicatricial (scarring). For the more common involutional or age-related cases, the primary defect involves horizontal lid laxity, disinsertion of the lower lid retractors and/or an overriding orbicularis muscle. Correction often involves use of the lateral tarsal strip procedure (see description under Ectropion Repair) to achieve tightening of the lower lid. Reattachment of the eyelid retractor muscles/aponeurosis may also be used in certain cases, either alone or in addition to a tarsal strip procedure.

Variant procedure or approaches: Cicatricial entropion results from a contracting scar of the tarsus and/or conjunctiva pulling the lid margin inward. Correction requires release of this tension and either a lid-splitting procedure with tarsal advancement, rotational grafts, or free mucosal grafts harvested from hard palate. In the latter case, nasal intubation will be required to allow access to the graft site. Quickert procedure involves the placement of 2–3 sutures under local anesthesia to evert the eyelid. Entropion frequently recurs after this procedure.

Usual preop diagnosis: Entropion of eyelid

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Lateral canthal region or area of conjunctival scarring. Mucosal graft may be harvested from hard palate.

Special instrumentation

Surgical loupes

Antibiotics

Non intraop

Surgical time

0.5–1 h

EBL

Minimal

Postop Care

Topical antibiotic ointment

Mortality

Rare
Lid malposition

Morbidity

Infection: Very rare

Pain score

1–2

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Patient Population Characteristics

Age range

Any age

Male:Female

1:1

Incidence

Common

Etiology

Congenital; aging; inflammation

Associated conditions

Cicatricial entropion can be associated with pemphigoid; Stevens-Johnson syndrome (a sometimes fatal form of erythema multiforme); chemical burns; trachoma.

Anesthetic Considerations

Entropion repair can usually be accomplished as an outpatient procedure using local anesthesia and MAC.

See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC (adult), p. 154, or for Pediatric Ophthalmic Surgery, p. 1175.

Suggested Reading

  1. See Suggested Reading following Ophthalmic Surgery section, p. 171.

Ptosis Repair

Surgical Considerations

Description: Ptosis (drooping of the upper eyelid margin) can be severe enough to obstruct the visual axis. Causes include congenital maldevelopment, mechanical traction, myogenic conditions (e.g., dystrophies, myasthenia gravis), neurogenic conditions (e.g., Horner's syndrome, cranial nerve III palsy), and aponeurotic dehiscence. The surgical approach depends primarily on the presence or absence of adequate levator muscle function that is responsible for elevating the upper eyelid. The most common etiology is age-related dehiscence or disinsertion of the levator aponeurosis from its normal attachment to the tarsus. Because levator muscle function is usually satisfactory in these patients, surgical correction involves reinserting the aponeurosis to the anterior tarsus alone or in combination with shortening of the aponeurosis by advancement or resection. Access is obtained by an incision in the upper eyelid crease. Removal of excess skin and orbicularis muscle (blepharoplasty) may be performed simultaneously. Although several formulas have been devised to determine the amount of aponeurotic shortening, intraop measurement usually is performed to ensure that the appropriate lid position and contour are achieved. This requires that the procedure be performed under local anesthesia and that the patient be positioned and draped in a way that allows him/her to sit upright during surgery.

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Figure 2-5. Frontalis sling (modified Crawford technique). Note location of brow and lid incisions and double rhomboid fascial slings. (Redrawn with permission from Duane's Clinical Ophthalmology, Vol. 5. Williams & Wilkins, Philadelphia, 2000.)

Variant procedure or approaches: In patients with levator muscle function that is not adequate to achieve eyelid elevation, a frontalis sling procedure is performed to elevate the upper eyelid (Fig. 2-5). More commonly required in children with congenital ptosis, this allows the patient to open the eye by elevating the brow. A variety of materials can be used to accomplish this suspension, including silicon rods or fascia. In children < 3 yr, autologous fascia lata can be harvested from the outer thigh from hip to knee. The material is tunneled beneath the skin and muscle from the brow incisions to the anterior tarsal region of the eyelid using Wright needles. After appropriate contour and height are achieved, the sling is secured and incisions are closed. Frontalis suspension usually is performed under GA in both adults and children.

Usual preop diagnosis: Ptosis

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Upper eyelid crease; brow; and lateral thigh (frontalis sling)

Special instrumentation

Surgical loupes

Antibiotics

Cefazolin 1 g iv

Surgical time

0.5–1 h

EBL

Minimal

Postop care

Topical antibiotic ointment; cool compresses

Mortality

Rare

Morbidity

Lid malposition (overcorrection, undercorrection, asymmetry)
Corneal exposure
Infection: More common with silicone rods

Pain score

1–2

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Patient Population Characteristics

Age range

Any Age

Male:Female

1:1

Incidence

Common

Etiology

Congenital; aponeurotic; neurogenic; myogenic; mechanical

Associated conditions

Neurogenic causes associated with myasthenia gravis; myogenic causes include chronic external ophthalmoplegia (can have dysrhythmias and SZ disorders); oculopharyngeal dystrophy

Anesthetic Considerations

Ptosis repair typically requires GA for infants and children and can be accomplished with local anesthesia and MAC as an outpatient procedure in adults. The need for patient cooperation during the surgery should be discussed with the surgeon and patient in advance. See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC, p. 154.

Suggested Reading

  1. See Suggested Reading following Ophthalmic Surgery section, p. 171.

Eyelid Reconstruction

Surgical Considerations

Description: Given the relatively small tissue area of the eyelids and their importance in both ocular health and cosmesis, excision of lid tumors often requires some form of reconstructive surgery. For lesions suspected of being malignant, frozen-sections are often performed prior to closing the defect. Additionally, Mohs technique (microscopically controlled serial excision) may be performed (usually by a dermatologist) to achieve clear margins, with reconstruction undertaken during a separate operation. During closure of full-thickness defects that involve the eyelid margin, attention is focused on aligning the lid in all dimensions (Fig. 2-6), while avoiding exposed sutures on the conjunctival surface that might damage the cornea. For small lid defects involving < ¼ of the lid length, direct closure often can be accomplished with release of the lateral canthal tendon (canthotomy and cantholysis) to reduce wound tension, if necessary.

Variant procedure or approaches: Larger excisions often require grafting techniques that are designed to replace both the anterior (skin/orbicularis) and posterior (tarsus/conjunctiva) lamellae of the eyelid. This can be accomplished with rotational grafts, a tarsoconjunctival advancement flap or free grafts of cartilage, hard palate, cadaver sclera, or composite grafts as posterior lamellar replacement materials.

Usual preop diagnosis: Basal-cell carcinoma; squamous-cell carcinoma; melanoma; sebaceous carcinoma; or trauma

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Upper and/or lower eyelid. Postauricular, supraclavicular, or hard palate if graft harvesting required

Special instrumentation

Surgical loupes

Antibiotics

Cefazolin 1 g iv

Surgical time

0.5–2 h

EBL

Minimal

Postop care

Topical antibiotic ointment; cool compresses; pressure dressing

Mortality

Rare

Morbidity

Graft failure
Lid deformity
Corneal exposure
Infection: < 1%

Pain score

2–3

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Patient Population Characteristics

Age range

Usually elderly

Male:Female

1:1

Incidence

Common

Etiology

Sun exposure-related malignancy

Associated conditions

Diseases of the elderly, including cardiovascular disease, HTN, and diabetes

 

Figure 2-6. Closure of full-thickness defect in the lower lid. The tarsal sutures and half-thickness tarsus are placed first, with the secondary closures at points A, B, C, and the eyelid margin. (Reproduced with permission from McCord CD, Tanenbaum M, eds: Oculoplastic Surgery, 2nd edition. Raven Press, New York, 1987.)

     

Anesthetic Considerations

Eyelid reconstruction can often be accomplished with local anesthesia and MAC. See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC, p. 154.

Suggested Readings

  1. Codner MA, WEinfeld AB: Comprehensive eyelid reconstruction. ANZ J Surg2007; 77(Suppl 1):A71.
  2. See Suggested Readings following Ophthalmic Surgery section, p. 171.

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Pterygium Excision

Surgical Considerations

Description: Pterygia are fibrovascular growths that originate in the interpalpebral conjunctiva and grow into the superficial layer of the cornea. They often produce refractive changes and/or obstruct the central visual axis and, thus, require removal. Although this procedure is often performed in the clinic or minor-procedure room, larger lesions may require an OR. In both settings, local anesthesia is applied both topically (tetracaine 0.5%) and subconjunctivally (lidocaine 2%). The lesion is dissected from the cornea and from the surrounding healthy conjunctiva, leaving a bed of bare sclera that may or may not be closed primarily (Fig. 2-7).

Variant procedure or approaches: For larger excisions and to decrease the rate of recurrence, conjunctival transposition or free-graft techniques can be used to cover the area of bare sclera. Topical antimetabolites, such as mitomycin-C, also may be applied to prevent recurrence.

Preop diagnosis or indications: Pterygium

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Interpalpebral area adjacent to involved limbus

Special instrumentation

Operating microscope

Antibiotics

Topical postop

Surgical time

15–45 min

EBL

Minimal

Postop care

Topical antibiotic ointment

Mortality

Rare

Morbidity

Recurrence: 37%, without adjunctive therapy or grafting
Extraocular muscle injury (higher risk in re-op eyes)

Pain score

1–2

Patient Population Characteristics

Age range

Usually young-to-middle age

Male:Female

1:1

Incidence

Common

Etiology

Related to sun exposure

References

  1. Ang LP, Chua JL, Tan DT: Current concepts and techniques in pterygium treatment. Curr Opin Ophthalmol2007; 18(4):308–13.

Anesthetic Considerations for Ophthalmic Surgical Procedures Under MAC

(Procedures covered: cataract extraction and other procedures; corneal transplant; trabeculectomy; ectropion-entropion repair; ptosis surgery; eyelid reconstruction; pterygium excision)

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Figure 2-7. Bare sclera excision can be started from the corneal apex or by incising around the conjunctival body of the pterygium. (Redrawn with permission from Duane's Clinical Ophthalmology, Vol 6. Williams & Wilkins, Philadelphia, 2000.)

Preoperative

Ophthalmic procedures that are of relatively short duration and those that result in minimal blood loss are being performed increasingly more often on an outpatient basis, usually with topical or regional anesthesia (e.g., retrobulbar or peribulbar blocks) under MAC (see p. B-3). Retrobulbar and peribulbar injections achieve excellent anesthesia and provide equal degrees of akinesia. Given the associated risk of inadvertent intrathecal injection of anesthetic, orbital hemorrhage, need for heavy sedation during injection, and delayed return of visual function postop, many cataract surgeries are performed using topical anesthesia. An additional benefit is that the bleeding risk is lower and the procedure can be performed safely in patients taking anticoagulants or with bleeding disorders. Although satisfactory pain relief usually is achieved with this method, the lack of akinesia requires a highly cooperative patient to prevent sudden eye movements during surgery. Some surgeons will supplement topical anesthesia with intracameral lidocaine (injections into the anterior chamber) although this has not been proven better than topical anesthetics alone in terms of patient comfort and satisfaction. Sub-Tenon's injection is another anesthetic technique used by many surgeons as a compromise between topical application and orbital injections. After preop application of topical anesthetics, a small incision is made in the bulbar conjunctiva, exposing the sub-Tenon's space. A blunt cannula is inserted under direct visualization and local anesthetic injected into the retrobulbar space. The main benefit is that no sharp needle is used, thereby reducing the risk of intrathecal injection and orbital hemorrhage from vessel injury. The onset of akinesia, however, is often delayed, and this technique still has the disadvantage of delayed return of postop visual function.

The pain on injection is slightly less with peribulbar blocks or sub-Tenon blocks as compared with retrobulbar techniques. The placement of the intravenous cannula was reported to represent the worst discomfort during cataract surgery, thus indicating that the eye blocks were not uncomfortable. Intraoperative pain is significantly less during retrobulbar blocks and peribulbar blocks than during topical anesthesia. Rates of ocular perforation following injection blocks are low (1 in 1000–10,000). A great majority (70%) of patients preferred peribulbar/retrobulbar anesthesia, 10% preferred topical, and 18% indicated no preference.

Because the majority of ocular procedures are performed on elderly patients, multiple coexisting medical illnesses are often present. A thorough preop H&P, along with appropriate ancillary studies are mandatory even though local anesthesia/MAC is planned. Contraindications to regional anesthesia/MAC for ocular surgery may include bleeding diathesis, open-eye injuries, claustrophobia, chronic cough, inability to lie flat, or patient refusal.

Respiratory

Elderly patients have increased incidence of hiatal hernia and, therefore, are at increased risk for pulmonary aspiration. Assess the patient's ability to lie flat for the duration of the procedure. Patients with chronic cough may require GA.
Tests: As indicated from H&P

Cardiovascular

Hx of HTN, CAD, CHF, or poor exercise tolerance should prompt a thorough investigation into the patient's cardiac status, including efficacy of current medications and recent ECG (compared with previous ECGs). Consultation with a cardiologist may be appropriate to optimize the patient's condition before surgery.
Tests: ECG; others (e.g., ECHO) as indicated from H&P

Diabetes

Diabetic patients are at increased risk for silent myocardial ischemia. Pulmonary aspiration 2° diabetic gastroparesis is also a risk in this population. Patients usually take 1/2 of their normal NPH (or other intermediate or long acting) insulin dose (on the morning of surgery); fasting blood sugar is checked; and an iv infusion of D5 LR is started if glucose < 90 mg/dl, or treated with regular insulin if glucose > 200 mg/dl. Blood sugar is checked intraop and postop. Patients on insulin pumps should maintain their basal infusion rate, and eliminate preprandial boluses. The anesthesiologist should ask the patient about their insulin sensitivity (the amount of insulin necessary to ↓ blood glucose by 50 mg/dl). Blood glucose should be monitored hourly.

Musculoskeletal

Arthritic changes make lying flat difficult for some patients. Careful positions and padding are essential.
A low-level remifentanil infusion (~0.05 mcg/kg/min) may be helpful in some cases

Hematologic

[check mark] for antiplatelet or anticoagulant drug use, particularly in patients undergoing lid or orbital procedures.
Tests: As indicated from H&P. (e.g., PT if patient is on anticoagulant)

Laboratory

Cr usual in patients > 64 yr; in other patients, as indicated from H&P

Premedication

Patients will benefit from a detailed explanation of events prior to surgery (including iv placement, application of monitors, performance of local block, ocular pressure, prepping eye, draping of the whole face, and provision of supplemental O2) and the assurance that the anesthesiologist will always be nearby, monitoring them. Midazolam (0.5–1 mg iv) is often beneficial. For patients with increased risk of aspiration (e.g., with hiatal hernia or diabetic gastroparesis) and for obese and/or very anxious patients, metoclopramide 10 mg iv may enhance gastric emptying.

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Intraoperative

Anesthetic technique: MAC (see p. B-3). Topical anesthesia typically is accomplished by the ophthalmologist, often using tetracaine or other long lasting LA, supplemented with 2% lidocaine, injected subconjunctivally. Placement of retrobulbar or peribulbar blocks may be painful and very short-acting agents (e.g., remifentanil 0.5–1 mcg/kg, alfentanil 5–7 mcg/kg, or propofol 30–50 mg) should be administered to minimize patient discomfort. Dose requirements vary significantly among patients, and the anesthesiologist should be prepared to treat ↓BP and apnea. Usually, further sedation is unnecessary and may interfere with patient cooperation during the surgery. Coughing should be avoided during the procedure, and the anesthesiologist must always be prepared to administer GA if necessary.

Retrobulbar block: Using a 25- or 27-ga needle (1.5”), the retrobulbar space is approached from the infratemporal quadrant of the orbit. The eye should be in a neutral or downward and medial position. Once the needle is positioned and there is no return of blood or CSF on aspiration, 3–5 mL of anesthetic solution is injected slowly. A facial nerve block is necessary to prevent eyelid movement. This can be accomplished by injecting 4-8 mL of anesthetic solution above and below the lateral aspect of the orbit. Typically, the anesthetic solution consists of a 50:50 mixture of 0.5% bupivacaine and 2% lidocaine with hyaluronidase.

Peribulbar block: Using a 25- or 27-ga needle (5/8”–1”), 5–6 mL of anesthetic solution is injected into the peribulbar space, entering just superior to the inferior rim of the orbit at the junction of the lateral and middle thirds of the lower lid. Although perforation of the globe and hemorrhage are still possible, direct injury to the optic nerve and subdural injection are not likely due to the length and position of the needle. Peribulbar blocks generally have a slower onset than retrobulbar blocks and are more likely to cause conjunctival swelling, which may interfere with surgery.

Sub-Tenon's Anesthesia: Injection of LA (often lidocaine ± epi) through a 22-ga cannula into the space below Tenon's capsule (episcleral membrane) produces ocular anesthesia in many ways similar to retrobulbar block. However, the onset is slower and akinesia is less reliable. The usual injection volume is 3–5 mL with more necessary if akinesia is required. Unlike retrobulbar block, significant complications with the technique are extremely rare.

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Blood and fluid requirements

IV: 18–20 ga × 1

NS/LR @ 1.5–3 mL/kg/h

Excessive fluids → bladder distention →↑BP, agitation

Monitoring

Standard monitors (see p. B-1).
Verbal response


It is important to remain in communication with the patient throughout the procedure. (Take care to avoid evoking head movement).

Positioning

[check mark] and pad pressure points.
[check mark] nonoperated eye.

Place pillows under knees to relieve back strain

Complications

Dysrhythmias, especially ↓HR

↑BP


Retrobulbar hemorrhage (1–3%)
Globe perforation

Convulsions 2° iv local anesthetic
Respiratory arrest
Oculocardiac reflex (OCR)→↓↓HR, ↓↓BP

Usually 2° traction on ocular/periocular tissues (see OCR, p. 1111)

2° anxiety, pain, etc. Rx: reassurance, local anesthetics, labetalol 5 mg or hydralazine 4-mg increments, as appropriate

Rx: pressure bandage; usually cancel surgery
If a needle perforation, usually no repair is necessary

Supportive treatment with IPPV; cancel surgery
2° subarachnoid injection. Rx: CPR
Rx: Stop stimulation; use atropine (see OCR, p. 1111)

Postoperative

Complications

Myocardial ischemia

Corneal abrasion
Photophobia
N/V
Diplopia

Rx: Provide O2; [check mark] BP; sublingual NTG; [check mark] ECG; cardiology consultation



Rx: Ondansetron 4 mg iv, ± metoclopramide, 10 mg iv

Pain management

Acetaminophen 325–1000 mg po

Table 2-1. Commonly Used Ophthalmic Drugs and Their Systemic Effects

Phenylephrine

An α-adrenergic agonist that causes mydriasis (pupillary dilation) and vasoconstriction to aid ocular surgery; however, it also can precipitate significant HTN and dysrhythmias.

Echothiophate

An irreversible cholinesterase inhibitor used in glaucoma treatment to cause miosis and ↓IOP. Its systemic absorption can reduce plasma cholinesterase activity and thereby prolong paralysis 2° to succinylcholine (usually not more than 20–30 min).

Timolol

A nonselective β-blocker that decreases production of aqueous humor →↓IOP. Rarely, it may be associated with atropine-resistant bradycardia, asthma, CHF, and ↓BP.

Acetazolamide

A carbonic anhydrase inhibitor used to ↓IOP. It also can cause diuresis and a hypokalemic metabolic acidosis.

Betaxolol

A relatively oculospecific β-blocker used to ↓IOP. Effects may be additive to systemic β-blockers.

Cyclopentolate

A commonly used mydriatic with the potential for CNS toxicity, including Sz, psychotic reactions, and dysarthria.

Atropine

An anticholinergic that produces mydriasis to aid with ocular examination and surgery. It also can precipitate central anticholinergic syndrome. (Sx range from dry mouth, tachycardia, agitation, delirium, and hallucinations to unconsciousness.) Physostigmine 0.01–0.03 mg/kg will increase central acetylcholine and reverse the symptoms. (It may be repeated after 15–30 min).

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Suggested Readings

  1. Ahmad S, Ahmad A: Complications of ophthalmologic nerve blocks: a review. J Clin Anesth2003; 15(7):564–9.
  2. Friedman DS, Bass EB, Lubomski LH, et al: Synthesis of the literature on the effectiveness of regional anesthesia for cataract surgery. Ophthalmology2001; 108:519–29.
  3. McGoldrick KE, Gayer S: Anesthesia and the eye. In Clinical Anesthesia, 5th edition. Barash PG, Cullen BF, Stoelting RK, eds. Lippincott Williams & Wilkins, Philadelphia: 2006, 974–96.
  4. Vann MA, Ogunnaike BO, Joshi GP: Sedation and anesthesia care for ophthalmologic surgery during local/regional anesthesia. Anesthesiology2007; 107(3):502–8.

Repair of Ruptured or Lacerated Globe

Surgical Considerations

Description: A ruptured globe involves a tear of either the corneal or scleral layers of the eye and can occur in the setting of blunt, penetrating, or perforating trauma. The primary goal of surgical repair is to replace extruded intraocular contents, close defects, and remove any foreign body. Orbital CT scans are performed preop to aid in the identification of the latter. To reduce the risk of causing further damage, complete examination of the eye is often delayed until the patient is in the controlled setting of the OR under GA. Although anterior injuries are readily identifiable, posterior injuries may require extensive exploration that can require a 360° opening of the conjunctiva and isolation of each extraocular muscle to allow adequate inspection of the entire scleral surface. Corneal lacerations usually are closed with 10-0 nylon sutures while 8-0 nylon or Vicryl may be used for scleral tissue. Until these wounds are closed, it is crucial that Valsalva maneuvers (which raise IOP), be avoided to prevent further extrusion of intraocular contents.

Variant procedures or approaches: After globe integrity has been established, other associated injuries may be addressed, including repair of conjunctival lacerations, extraocular muscle injuries/detachments, retinal detachments, or removal of a traumatic cataract.

Usual preop diagnosis: Ruptured globe

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Conjunctival peritomy (360° conjunctival incision) to allow exposure of posterior sclera

Special instrumentation

Operating microscope

Antibiotics

IV gentamicin (80 mg) and cefazolin (1 g); subconjunctival and topical antibiotics

Closing considerations

Avoid Valsalva-like maneuvers (coughing, bucking, etc.)

Surgical time

1–2 h

EBL

Minimal

Postop care

Hospital admission for iv antibiotics

Mortality

Rare

Morbidity

Wound leak
Infection: Rate depends on injury
Sympathetic ophthalmia: Rare

Pain score

4

P.158

Patient Population Characteristics

Age range

Usually < 40 yr

Male:Female

9:1

Incidence

Common

Etiology

Work- or sports-related injury; motor vehicle accidents

Associated conditions

Intoxication; orbital/facial trauma; head injury

Anesthetic Considerations

Preoperative

This is a generally healthy patient population; however, patients with penetrating eye injuries present the anesthesiologist with two special challenges: (1) They invariably have full stomachs, resulting in risk of aspiration. (2) They are at risk of blindness 2° ↑IOP and loss of ocular contents, which may be a result of coughing, crying, and/or struggling during induction. Normal IOP ranges from 10–22 mmHg, depending on the rate of formation and drainage of aqueous humor, choroidal blood volume, scleral rigidity, extraocular muscle tone, as well as extrinsic pressure on the eye (e.g., a poorly fitting mask or retrobulbar hematoma). Patient movement, coughing, straining, vomiting, hypercarbia, HTN, and ET intubation also may ↑IOP to 40 mmHg or more.

Full-stomach precautions

Consider patient to have a full stomach if the injury occurred within 8 h of the last meal. Pain and anxiety due to trauma will delay gastric emptying. Goal is to minimize risk of aspiration pneumonitis by decreasing gastric volume and acidity. Consider premedication with metoclopramide (10–20 mg iv), antacids such as Na citrate (15–30 mL po, immediately prior to induction), and H2-histamine receptor antagonists (ranitidine [50 mg iv]). H2-histamine receptor antagonists, however, have no effect on the pH of gastric secretions present in the stomach prior to administration and are, therefore, of limited value in patients presenting for emergency surgery. If patient has Hx of smoking or is an asthmatic, consider preop use of inhalers such as albuterol (2–4 puffs).

Associated Injuries

A ruptured globe may be only one of multiple injuries to the head and neck or other structures. Other injuries should be excluded preoperatively.

Laboratory

Tests as indicated from H&P

Premedication

Patients often are very anxious and may benefit from benzodiazepines (e.g., for pediatric population, midazolam 0.5–0.75 mg/kg po in cola or apple juice, 15–30 mL). Avoid narcotic premedication, which may ↑ nausea and possibility of emesis.

Intraoperative

Anesthetic technique: GETA. Regional anesthesia (e.g., retrobulbar block) is contraindicated in patients with open-eye injury because of ↑IOP, which may accompany injection of local anesthetic behind the globe. Thus, in spite of the increased risk of aspiration from a full stomach, GETA is recommended. In patients where the risk of GA is unacceptably high (e.g., extensive pulmonary or unstable cardiac disease) surgical repair can be accomplished using topical anesthesia (see Auffarth GU et al.).

Induction

To protect the airway and prevent ↑IOP, a rapid-sequence induction with cricoid pressure and a smooth intubation are required. Although the choice of induction agent is relatively straightforward—propofol 1–2 mg/kg or STP 3–5 mg/kg—the choice of neuromuscular blocking agents for facilitating intubation is controversial. Succinylcholine provides a rapid onset, short duration of action, and excellent intubating conditions, but it also transiently increases IOP. This ↑IOP is not always attenuated by pretreatment with a nondepolarizing agent (e.g., d-tubocurarine). Rocuronium (1 mg/kg) produces muscle relaxation in 1–2 min and may be a satisfactory alternative to succinylcholine; however, a premature attempt at intubation may significantly ↑IOP as a result of coughing and straining. Of interest, there are no reports in the literature documenting exacerbation of eye injuries with the use of succinylcholine following pretreatment with a NMR. Given that the anesthesiologist's main concern is safe airway management, the following is a suggested induction plan:
(1) Preoxygenation, avoiding external pressure on the eye from face mask
(2) Pretreatment with a nondepolarizing relaxant (e.g., d-tubocurarine 0.06 mg/kg or equivalent), followed by iv lidocaine (1 mg/kg) and fentanyl (2–3 mcg/kg) to blunt the cardiovascular response to laryngoscopy and intubation
(3) 4 min later, with cricoid pressure, induce with STP (3–5 mg/kg) or propofol (1–2 mg/kg) and succinylcholine (1.5 mg/kg). Intubate with oral RAE tube. Note: for pediatric patients, it might be appropriate to induce with sevoflurane while maintaining cricoid pressure and intubating when the patient is deeply anesthetized. Trying to start an iv prior to induction may precipitate struggling and crying, leading to further eye injury.

Maintenance

Standard maintenance or TIVA (see p. B-2). Avoid hypercapnia, which →↑IOP. Muscle relaxation is mandatory until the eye is surgically closed. Humidify gases for pediatric patients.

Emergence

Decompress the stomach with OG tube. Goal is smooth emergence and extubation with patient awake with intact airway reflexes. IV lidocaine (1.5 mg/kg) 5 min before extubation; posterior pharyngeal suctioning with patient deeply anesthetized, combined with a small amount of narcotic (remifentanil ~1 mcg/kg), may blunt cough reflex prior to extubation. The common occurrence of PONV requires administration of intraop antiemetics (e.g., metoclopramide 10 mg iv, and ondansetron 4 mg iv 30 min before end of surgery).

Blood and fluid requirements

IV: 18–20 ga ×1 (adult)
20 ga ×1 (child)
NS/LR @ 5–10 mL/kg/h
Warm fluids

Monitoring

Standard monitors (see p. B-1)

Neuromuscular blockade must be monitored closely and additional relaxant given as necessary to prevent patient movement during surgery.

Positioning

[check mark] and pad pressure points
[check mark] nonoperated eye

Complications

↑ IOP with extrusion of intraocular contents
Aspiration of gastric contents

IOP (normal = ~10–22 mmHg) increased by: blink = 10–15 mmHg; forced closure = > 70 mmHg.

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Postoperative

Complications

N/V


Aspiration pneumonitis
Photophobia
Diplopia
Hemorrhagic retinopathy
Corneal abrasion

Rx: Metoclopramide 10 mg iv, droperidol 0.625 mg iv (with due respect to the black-box warning), ondansetron 4 mg iv
Provide O2 by face mask, if not intubated. Follow O2 sat. [check mark] CXR

Pain management

Acetaminophen

Occasionally, parenteral opiates (see p. C-2)

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Suggested Readings

  1. Auffarth GU, Vargas LG, Klett J, et al: Repair of a ruptured globe using topical anesthesia. J Cataract Refract Surg2004; 30(3):726–9.
  2. Boscia F, La Tegola MG, Columbo G, et al: Combined topical anesthesia and sedation for open-globe injuries in selected patients. Ophthalmology2003; 110(8):1555–9.
  3. Chidiac EJ, Raiskin AO: Succinylcholine and the open eye. Ophthalmol Clin North Am2006; 19(2):279–85.
  4. Kumar C, Doods C, Fanning G, eds: Ophthalmic Anaesthesia. Lisse: Swets and Zeitlinger BV, 2002.
  5. McGoldrick KE, Gayer S: Anesthesia and the eye. In Clinical Anesthesia,5th edition. Barash PG, Cullen BF, Stoelting RK, eds. Lippincott Williams & Wilkins, Philadelphia, 2006.
  6. Vachon CA, Warner DO, Bacon DR: Succinylcholine and the open globe. Tracing the teaching. Anesthesiology2003; 99:220–3.

Dacryocystorhinostomy (DCR)

Surgical Considerations

Description: Dacryocystorhinostomy (DCR) is performed for patients with symptomatic obstruction of the nasolacrimal duct (NLD) and is commonly associated with chronic dacryocystitis. The procedure is designed to create a fistula from the common canaliculus to the nasopharynx, which bypasses the site of obstruction. DCR can be performed under GA or local anesthesia (subcutaneous and nasal cavity cocaine 4%). Intranasal phenylephrine and/or cocaine pledgets are often placed to decrease mucosal bleeding. A skin incision is made below the medial canthal tendon that is extended to the lacrimal fossa with blunt dissection. Bleeding can be excessive if the angular vessels are injured. The now exposed periosteum is incised and a 1.5 cm × 1.5 cm osteotomy is created with a burr and/or Kerrison punch, exiting at the level of the middle meatus. A Crawford lacrimal probe attached to silicone tubing is inserted into the superior punctum and advanced into the lacrimal sac, which is then opened along its medial wall. Following incision of the nasal mucosa through the osteotomy, the posterior flap of the lacrimal sac is sutured to the posterior nasal mucosa flap. The probe is advanced through the osteotomy and into the middle meatus, where it is retrieved through the nare. The second end of the probe is advanced along the same path but beginning through the inferior punctum. The ends of the silicone tubing are tied together in the nare and the anterior flaps of lacrimal sac and nasal mucosa are sutured together. Thrombin and gel foam can be used to control mucosal bleeding and the skin is reapproximated after ensuring hemostasis.

Variant procedures or approaches: If the lacrimal obstruction is more proximal to the lacrimal sac, a Jones tube can be placed (Fig. 2-8), creating an artificial lumen from the conjunctiva to the nasopharynx to bypass the entire nasolacrimal drainage system. An endonasal approach using a rigid endoscopic ± laser offers the advantage of no skin incision, good visualization of intranasal pathology and less post-op discomfort.

Usual preop diagnosis: NLD obstruction

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

15 mm, just below medial canthus (Fig. 2-9)

Special instrumentation

Headlight; surgical loupes

Unique considerations

Nasal packing with phenylephrine/cocaine. Blood may drain into upper airway during surgery

Antibiotics

Cefazolin 1 g iv

Surgical time

1–1.5 h

EBL

100–200 mL

Postop care

Outpatient

Mortality

Rare

Morbidity

Failure to drain
Bleeding: 5%
Infection: < 1%

Pain score

3–4

P.161

Patient Population Characteristics

Age range

30–70 yr

Male:Female

1:1

Incidence

Common

Etiology

Usually scarring from prior infection or trauma

Associated conditions

Deviated septum; nasal polyps; nasopharyngeal masses

 

Figure 2-8. Insertion of a Pyrex Jone's tube. (Reproduced with permission from McCord CD, Tanenbaum M, Nunery WR: Oculoplastic Surgery. Raven Press, 1995.)

     

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Figure 2-9. Linear skin incision for a standard DCR. (Reproduced with permission from Wright KW: Textbook of Ophthalmology. Williams & Wilkins, Philadelphia, 1997.)

Anesthetic Considerations

DCR can be performed with local anesthetic and MAC or under GA depending on patient and surgeon preferences. See Anesthetic Considerations for Ophthalmic Surgical Procedures under MAC: p. 154 or GA: p. 165.

Suggested Readings

  1. See Suggested Reading following Ophthalmic Surgery section, p. 171.
  2. Watkins LM, Janfaza P, Rubin PA: The evolution of endonasal dacryocystorhinostomy. Surg Ophthalmol2003; 48(1):73–84.

Enucleation

Surgical Considerations

Description: Enucleation involves removal of the entire globe and a portion of the optic nerve. It usually is performed for painful blind eyes or intraocular tumors (e.g., retinoblastoma, melanoma). The surrounding ocular adnexa, including the conjunctiva, Tenon's connective tissue, and extraocular muscles, are left in place to secure an orbital implant. The procedure begins with a 360° conjunctival incision (peritomy) at the limbus, allowing exposure of the underlying extraocular muscles and sclera. Each of the recti muscles is isolated with a muscle hook and secured with fixation sutures before disinsertion from the globe. The oblique muscles are cut and allowed to retract into the orbit (Fig. 2-10). A curved clamp is closed across the optic nerve ~3–10 mm posterior to the globe, and the nerve is cut and the globe removed. After hemostasis has been ensured, an orbital implant (polymethylmethacrylate

P.163

or hydroxyapatite) is placed into the socket. The overlying muscles, connective tissue, and conjunctiva are closed to improve motility and prevent extrusion.

 

Figure 2-10. Each of the four recti is isolated with 6-0 Dexon suture. The superior oblique tendon is detached. The inferior oblique is sutured to the inferior border of the lateral rectus. 4-0 silk traction sutures are in place over the medial and lateral rectus stump. The globe is rotated laterally, while a curved clamp is introduced from the medial direction. Either a curved scissors or an enucleation snare may be used to transect the optic nerve. (Reproduced with permission form McCord, CD Jr, Tanenbaum M, Nunery WR: Oculoplastic Surgery. Raven Press, Philadelphia, 1995.)

Variant procedure or approaches: Evisceration involves removing all intraocular contents through a corneoscleral incision, leaving the scleral shell with the attached adnexa in place. This usually is performed in cases of endophthalmitis, but never if malignancy is suspected. Exenteration is a more extensive procedure for the management of aggressive malignant tumors or infections where all orbital tissue, often including surrounding orbital bone and adjacent sinuses, is removed.

Usual preop diagnosis: Painful blind eye; intraocular tumors; sympathetic ophthalmia

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

360° conjunctival (peritomy)

Special
instrumentation

Surgical loupes

Antibiotics

Irrigate socket with gentamicin postop

Surgical time

1 h

EBL


< 100 mL

Postop care

Outpatient

Mortality

Rare

Morbidity

Extrusion of implant
Infection: < 1%

Pain score

3–4

P.164

Patient Population Characteristics

Age range

Any age

Male:Female

1:1

Incidence

Relatively common

Etiology

Trauma; infection; glaucoma; tumors (e.g., retinoblastoma, melanoma); inflammation

Associated conditions

Diabetes mellitus

Anesthetic Considerations

See Anesthetic Considerations for Ophthalmic Surgical Procedures under GA, p. 165.

Suggested Reading

  1. See Suggested Reading following Ophthalmic Surgery section, p. 171.

Orbitotomy—Anterior and Lateral

Surgical Considerations

Description: Surgical access to the orbit is required for biopsy/excision of masses, drainage of orbital abscesses, removal of a foreign body, or repair of orbital fractures, among other procedures. The orbit may be divided into several compartments and the surgical approach will vary by the location and size of the lesion. In general, an anterior orbitotomy is used for small tumors in the anterior orbit and can be approached from a transconjunctival, transseptal, or transperiosteal incision. By contrast, a lateral orbitotomy allows for removal of larger masses located further posteriorly in the orbit, as well as those lesions involving the lacrimal gland. In this procedure, the skin incision can be placed just under the brow (Stallard-Wright), in the lid crease with lateral extension, or higher in the eyebrow (coronal). The dissection is carried down to the periosteum, which is then incised and reflected. The lateral orbital wall is exposed and an osteotomy is performed using an oscillating saw, after preplacing suture holes with a power drill. The section of bone is removed with a clamp and the periorbita is opened, allowing intraorbital dissection. After biopsy or removal of the mass, the periorbita is closed and the bone fragment replaced.

Variant procedures or approaches: A medial orbitotomy is often required to access lesions that are located medial to the optic nerve.

Usual preop diagnosis: Orbital mass; fractures; foreign body; abscess

P.165

Summary of Procedures

Position

Supine, table rotated 90–180°

Incision

Variable (see above)

Special instrumentation

Surgical loupes

Antibiotics

Cefazolin 1 g iv

Surgical time

1–3 h

EBL

Usually minimal, unless vascular tumor

Mortality

Rare

Morbidity

Orbital hemorrhage
Impaired ocular motility
Secondary infection
Loss of vision
Infection: < 1%

Pain score

3–6

Patient Population Characteristics

Age range

Any age

Male:Female

1:1

Incidence

Fairly common

Etiology

Tumor, such as hemangioma, lymphangioma, lymphoma; lacrimal gland tumors; infection; fracture; foreign body

Anesthetic Considerations

[Procedures covered: dacryocystorhinostomy (DCR); enucleation; anterior and lateral orbitotomy.]

Preoperative

Patients presenting for DCR, enucleation, and orbitotomy represent a diverse population. These patients are generally healthy, aside from the infection, tumor, or trauma underlying their ocular or periocular pathology. Preop evaluation should focus on possible coexisting disease and the systemic manifestations of previous therapeutic interventions (e.g., chemotherapy and drugs used to treat glaucoma).

Laboratory

Tests as indicated from H&P

Premedication

Standard premedication (see p. B-1)

Intraoperative

Anesthetic technique

GETA

Induction

Standard induction (see p. B-2). An oral RAE ETT may be preferred.

Maintenance

Standard maintenance (see, p. B-2). Muscle relaxation is not required.

Emergence

No special considerations. The common occurrence of PONV requires the administration of intraop antiemetics (e.g., metoclopramide 10 mg iv, and ondansetron 4 mg iv).

Blood and fluid requirements

Blood loss variable

IV: 18-20 ga ×1
NS/LR @ 4–6 mL/kg/h

Monitoring

Standard monitors (see p. B-1)

Positioning

Table rotated 90°
[check mark] and pad pressure points
[check mark] nonoperated eye

Complications

Oculocardiac reflex (OCR) → ↓↓HR

See discussion in Anesthetic Considerations for Strabismus Surgery, p. 1175

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Postoperative

Complications

PONV

Rx: Metoclopramide 10 mg iv, and/or ondansetron 4 mg iv

Pain management

Acetaminophen

Occasionally parenteral opiates (see p. C-2)

Retinal Surgery

Surgical Considerations

Description: Retinal surgery is performed for a wide variety of conditions (see Usual preop diagnoses, below). Most retinal detachments are due to one or more small tears in the retina. Retinal detachments are classified as traction, exudative (not usually treated with surgery), or rhegmatogenous (rupture, tear). Children, especially those with ROP or trauma, may develop retinal detachments. In adults, retinal detachments are most frequently associated with diabetes, myopia, trauma, and previous cataract surgery. Rhegmatogenous retinal detachments (more common in adults) start off with a small retinal tear, which allows the vitreous to seep in between the retina and pigment epithelium, forcing retinal separation. Sx range from floaters and flashes to showers of black specks and, ultimately, to a dark shadow that impinges on the field of vision. Retinal detachments may be complicated by proliferative vitreoretinopathy (PVR), in which scar tissue grows along the surface of the retina, rendering it stiff and difficult to reattach. Less commonly, retinal detachments are induced by other forms of vitreoretinal traction, or by trauma involving an open globe. Care must be taken to avoid any increase in intraocular pressure (IOP) in an eye that may be ruptured. On rare occasion, retinal detachments are due to the formation of a giant retinal tear. Just as rarely, retinal surgery may be done on premature infants in an effort to prevent or repair retinal detachments. The ultimate aim of retinal surgery is the preservation or recovery of vision through the restoration of normal posterior segment anatomy. (Anatomy of the eye is shown in Fig. 2-11.)

Retinal surgery may involve various procedures alone or in combination, including scleral buckling, vitrectomy, gas-fluid exchange, and injection of vitreous substitutes. Scleral buckles are silicone rubber appliances sutured to the sclera to indent the eye wall, thereby relieving vitreous traction and functionally closing retinal tears. This is an external procedure in which the eye may either not be entered at all or entered with a small needle puncture through the sclera for drainage of subretinal fluid.

Cryotherapy or lasers are used frequently to establish chorioretinal adhesions around retinal tears. Cryotherapy is applied to the sclera; a laser is applied with a fiber optic cable introduced into the vitreous cavity during vitrectomy surgery, often in combination with a wide-field viewing system. It also can be administered with an indirect ophthalmoscope delivery system for those eyes not undergoing vitrectomy.

Simple detachments frequently can be repaired by a pneumatic retinopexy, in which retinal tears are treated with cryotherapy and/or laser, and an expanding gas is injected into the vitreous cavity. This technique usually is done in

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phakic eyes (eyes with intact lens) with tears between the 9 o'clock and 4 o'clock positions. Pneumatic retinopexy usually is done as an outpatient office procedure, with local anesthesia, or, less commonly, MAC. The other procedures discussed usually are done with MAC, although GA may be used, according to surgeon's preference and the patient's systemic condition. Some surgeons inject retrobulbar or subconjunctival bupivacaine at the end of a procedure done under GA to decrease postop pain.

 

Figure 2-11. Eye anatomy. (Reproduced with permission from Langston D, ed: Manual of Ocular Diagnosis and Therapy, 2nd edition. Little, Brown, Boston: 1985.)

Vitrectomy (removal of vitreous) is commonly performed to reduce traction on the retina (↓retinal detachment), clear blood and debris and remove scar tissue. It is an intraocular procedure in which three 20–25-ga openings are made into the vitreous cavity with a myringotomy blade 3–4 mm posterior to the limbus (junction of the cornea and sclera.) One of these openings in the inferotemporal quadrant is used for infusion of balanced salt solution via a sutured or transconjunctival trochar-based cannula. The remaining openings are at the 9:30 and 2:30 o'clock positions. One is used for a hand-held fiber optic light; the other, for insertion of a variety of manual and automated instruments, including suction cutters, scissors, and forceps, used to remove and section abnormal tissue within the vitreous cavity.

Visualization of the retina during vitrectomy is made possible by a contact lens, which is either sutured to the eye or held in position by an assistant. Some of these lenses provide a wide-field, inverted view of the retina, necessitating an image inverter on the microscope. Alternatively, a noncontact, wide-field lens may be positioned just above the cornea, suspended from the microscope. Balanced salt solution replaces the vitreous and other tissues removed during the operation. A bubble of gas is sometimes introduced into the vitreous cavity during a scleral buckle or a vitrectomy when the surgeon wants an internal tamponade of retinal tears that cannot be closed adequately by a scleral buckle

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alone. N2O must be discontinued before a gas-fluid exchange to avoid an intraop or postop change in gas bubble size, possibly accompanied by abnormal IOP.

In the case of a giant retinal tear, a gas-fluid exchange formerly was performed with the patient in the prone position toward the end of the operation. This required that the patient be on a Stryker frame, so that he or she could be moved from the supine to the prone position for the gas-fluid exchange. Perfluorocarbon liquids now obviate the need for a Stryker frame.

Liquid vitreous substitutes, such as perfluorocarbon liquids or silicone oil, are sometimes introduced into the vitreous cavity during a vitrectomy. Perfluorocarbon liquids are heavier than water and are used as an intraoperative tool to unfold the detached retina; they are removed at the end of the procedure. Perfluorocarbon liquids make possible repair of giant retinal tears in the supine position, thus eliminating the need for a Stryker frame. They also facilitate reattaching the retina when PVR is present, by allowing a relaxing retinotomy for those situations where the retina is too stiff and foreshortened to be reattached by less invasive measures. Silicone oil is used for complex detachments in which a long-term, internal tamponade of retinal tears is deemed necessary to prevent redetachment. It usually is removed a few months postoperatively with a second operation.

Usual preop diagnosis: Simple and complex retinal detachment; diabetic retinopathy; vitreous hemorrhage or opacification; macular epiretinal membranes; other surgically correctable macular conditions, such as macular holes or macular degeneration with subfoveal choroidal neovascularization or hemorrhage; dislocated intraocular lenses; endophthalmitis; macular degeneration with posterior segment trauma, including repair of ruptured globes and removal of intraocular foreign bodies; retinopathy of prematurity (ROP).

Summary of Procedures

Position

Supine

Incision

Transconjunctival

Special instrumentation

Vitrectomy machine; cryoprobe; laser; indirect ophthalmoscope; microscope

Unique considerations

Ruptured globe—avoid ↑IOP. Stop N2O 5–10 min before a gas-fluid exchange.

Antibiotics

May use iv antibiotics at the start of surgery, in addition to subconjunctival antibiotics at conclusion of surgery.

Surgical time

Pneumatic retinopexy: 20 min
Scleral buckle: 30 min to 2 h
Vitrectomy: 1–4+ h

Closing considerations

Try to avoid postop bucking or vomiting

EBL

None

Postop care

Prone positioning, if gas was injected

Mortality

Extremely rare

Morbidity

Hemorrhage: < 5%
Retinal detachment: < 5%
Infection: < 1%

Pain score

6

Patient Population Characteristics

Age range

Usually adults; occasionally premature infants (ROP) and children (retinal detachment or trauma)

Male:Female

1:1

Incidence

1/20,000 phakic; 1/250 pseudophakic (postcataract extraction with placement of intraocular lens)

Etiology

Majority idiopathic; some related to systemic disease or induced by trauma

Associated conditions

Idiopathic: retinal detachment, epiretinal membrane, macular hole
Diabetic retinopathy: vitreous hemorrhage or traction retinal detachment
Macular degeneration: subfoveal choroidal neovascularization or hemorrhage
Trauma: vitreous hemorrhage, retinal detachment, ruptured globe
Intraocular foreign body (IOFB)
HTN: vitreous hemorrhage
Extreme prematurity: ROP, retinal detachment

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Anesthetic Considerations

Preoperative

In MAC cases, the need for anxiolytics can often be reduced or eliminated by discussing in detail what will happen to the patient during the procedure and by addressing patient concerns (e.g., claustrophobia, positional pain, supine dyspnea, etc.). Most vitreous and retinal procedures can be accomplished using regional anesthetic techniques (retrobulbar, peribulbar, or sub-Tenon's block with MAC. Procedures requiring more than 2 hrs and patients (or surgeons) with special needs (e.g., claustrophobia, uncooperative, immature) may benefit from GA. With MAC, the anesthesiologist's goal should be a comfortable, cooperative patient who can lie completely still without falling asleep (uncontrolled movement when suddenly awakened) for 1–2 hours.

Cardiovascular

Mannitol decreases IOP by increasing plasma oncotic pressure relative to aqueous humor pressure. It usually is given just before or during surgery. Total dosage should not exceed 1.5–2 g/kg iv over a 30–60 min period. Rapid infusion of large doses of mannitol may precipitate CHF, pulmonary edema, electrolyte abnormalities, HTN, and, possibly, myocardial ischemia; hence, the importance of a thorough evaluation of the patient's renal and cardiovascular status prior to administering mannitol.
Tests: As indicated from H&P

Diabetes

Diabetic patients are at increased risk for silent myocardial ischemia. Pulmonary aspiration 2° diabetic gastroparesis is also a risk in this population. Patients usually take 1/2 or 1/3 of their normal NPH insulin dose (on the morning of surgery); fasting blood sugar is checked; and an iv infusion of D5 LR is started if glucose < 90 mg/dl, or treated with regular insulin if glucose > 200 mg/dl. Blood sugar is checked intraop and postop.

Renal

Acetazolamide, a carbonic anhydrase inhibitor, decreases secretion of aqueous humor. It also inhibits renal carbonic anhydrase, thereby facilitating the loss of HCO3, Na+, K+, and water. Thus, patients on chronic therapy may be acidotic, hypokalemic, and hyponatremic.
Tests: Electrolytes; others as indicated from H&P

Hematologic

[check mark] for sickle-cell disease. Sickle-cell trait is not commonly associated with periop complications. Patients with sickle-cell anemia should be well hydrated and transfused preop, as necessary to increase HbA concentration > 40%.

Laboratory

Tests as indicated from H&P

Premedication

Midazolam 0.5 mg/kg po for pediatric patients (~30 min to peak effect; ~30 min duration of effect) and midazolam 1–2 mg iv incrementally for adults, will help alleviate anxiety. Avoid excessive sedation (respiratory depression) in sickle-cell patients. Surgeons prefer a normal IOP during retinal reattachment surgery and, therefore, patients may be given acetazolamide or mannitol to decrease IOP.

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Intraoperative

Anesthetic technique: Retinal detachment surgery may be performed under regional anesthesia (e.g., retrobulbar or peribulbar block); however, if the surgery is expected to be > 2 h, GETA may be preferable.

Induction

Standard induction (see p. B-2) is appropriate for these patients with care being taken not to put pressure on the affected eye with the face mask.

Maintenance

Standard maintenance (see p. B-2). Ophthalmologists, however, may use expanding gases, such as sulfur hexafluoride (SF6) or perfluoropropane (C3F8), for internal tamponade of the retinal tears and, if N2O is used, the injected bubble may expand rapidly, causing a dramatic rise in IOP. This can impair retinal blood flow. N2O, if used at all, should be D/C'd at least 15 min before gas injection. If the patient needs a second surgery and GA after the first gas injection, N2O should be avoided for at least 5 d after the air injection, 10 d after the SF6 injection, and 15–30 d after the C3F8. Given the importance of patient immobility, nondepolarizing muscle relaxants may be advantageous, especially if N2O is D/C'd.

Emergence

Use narcotics for pain control and iv lidocaine 1.0–1.5 mg/kg 5 min prior to extubation to provide smooth emergence. The common occurrence of PONV requires the administration of intraop antiemetics (e.g., metoclopramide 10 mg iv and ondansetron 4 mg iv 30 min before the end of surgery).

Blood and fluid requirements

IV: 18–20 ga ×1 (adult)
20 ga ×1 (child)
NS/LR @ 4-6 mL/kg/h

Monitoring

Standard monitors (see p. B-1)

Processed EEG may be useful in monitoring level of sedation
Care should be taken to avoid CO2 accumulation under the drapes in MAC cases. A suction line can be used to improve air circulation under the drape

Positioning

[check mark] and pad pressure points

[check mark] and pad nonsurgical eye

For long MAC cases, short “time-outs” should be taken to allow patients to reposition themselves

Complications

Oculocardiac reflex (OCR)

See Intraoperative Complications under Anesthetic Considerations for Strabismus Surgery, p. 1175

Postoperative

Complications

PONV
Corneal abrasion
Vitreous hemorrhage
Glaucoma
Ptosis
Diplopia
Loss of vision
Infection

Rx: Ondansetron 4 mg iv ± Metoclopramide 10 mg iv; however, eye pain (e.g., 2° to corneal abrasion) may also cause N/V. If this is the case, treat pain (ophthalmology consult).






Persistently low BP → retinal ischemia and central retinal artery occlusion

Pain management

Retrobulbar anesthesia

Meperidine 0.5–1 mg/kg/h iv

Tests

None routinely required

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Suggested Readings

  1. Charles S, Fanning GL: Anesthesia considerations for vitreoretinal surgery. Ophthalmol Clin North Am2006; 19(2):239–43.
  2. Hamilton RC: Techniques of orbital regional anaesthesia. Brit J Anaesth1995; 75:88–92.
  3. McGoldrick KE, Gayer SI: Anesthesia and the Eye.In Clinical Anesthesia, 5th edition. Barash PG, Cullen BF, Stoelting RK, eds. Lippincott Williams & Wilkins, Philadelphia: 2006, 969–88.
  4. Ryan SJ, Hinton DR, et al., ed: Retina,4th edition. CV Mosby Co, St. Louis: 2005.

General Ophthalmic Surgery Suggested Readings

  1. Ahmad S, Ahmad A: Complications of ophthalmologic nerve blocks: a review. J Clin Anesth2003; 15(7):564–9.
  2. Albert DM, Jakobiec FA, eds: Principles and Practice of Ophthalmology.WB Saunders, Philadelphia: 2000;1463–76.
  3. External Disease and Cornea: Basic and Clinical Science Course.The Foundation of the American Academy of Ophthalmology 1998; 8:411–36.
  4. Greenbaum G, ed: Ocular Anesthesia.WB Saunders, Philadelphia: 1997.
  5. Krachmer JH, Mannis MJ, Holland EJ: Cornea.Mosby-Year Book, St. Louis: 1997.
  6. Lens and Cataract. Basic and Clinical Science Course.The Foundation of the American Academy of Ophthalmology 2001;11:66–186.
  7. Levine MR, ed: Manual of Oculoplastic Surgery,2nd edition. Butterworth-Heinmann, New York: 1996.
  8. Moster MR, Azura-Blanco A, eds: Ocular anesthesia. Ophthalmol Clin North Am2006;19:151–322.
  9. Nesi FA, Smith BC, eds: Ophthalmic Plastic and Reconstructive Surgery,2nd edition. Mosby-Year Book, St. Louis: 1997.
  10. Phelps CD, Hansjoerg EJ, eds: Manual of Common Ophthalmic Surgical Procedures.Churchill Livingstone, New York: 1986.
  11. Pokhrel PK, Loftus SA: Ocular emergencies. Am Fam Physician2007; 76(6):829–36.
  12. Shields MB: Textbook of Glaucoma,4th edition. Williams & Wilkins, Baltimore: 1998.
  13. Waltman SR, Keates RH, Hoyt CS, et al, eds: Surgery of the Eye.Churchill Livingstone, New York: 1988.