Seminars in Ophthalmology, 2014; 29(5–6): 421–428 ! Informa Healthcare USA, Inc. ISSN: 0882-0538 print / 1744-5205 online DOI: 10.3109/08820538.2014.959190
REVIEW
Complications of Strabismus Surgery: Incidence and Risk Factors Michael J. Wan and David G. Hunter
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Department of Ophthalmology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts, USA
ABSTRACT Purpose: To perform a systematic review of the complications of strabismus surgery, focusing on incidence and risk factors. Material and Methods: A systematic literature search was performed using the Medline and Cochrane databases. Results: Local complications, such as conjunctival injection and mild scarring, are almost universal but only rarely have long-term clinical significance. There are several important complications that are uncommon but associated with significant long-term sequelae, including slipped muscles, lost muscles, stretched scars, incarcerated muscles, pulled-in-two syndrome, periocular infections, orbital cellulitis, scleral perforations, retinal detachments, endophthalmitis, anterior segment ischemia, and surgical errors. Discussion: Strabismus surgery is associated with a number of common and serious complications, and it is important for both surgeons and patients to be aware of the risks. Keywords: Complications, postoperative, review, strabismus, surgery
INTRODUCTION
When consenting patients for strabismus surgery, it is incumbent on ophthalmologists to know the approximate incidence of potential complications and the various factors that may increase the risk in a given patient. According to the American Academy of Ophthalmology (AAO), physicians must disclose ‘‘any risks or potential complications that are sufficiently common or significant that they might reasonably influence the patient’s decision to accept the proposed procedure.’’3 Since a large number of ophthalmologists will not personally encounter many of the rare complications of strabismus surgery, it is necessary to derive the incidence of such complications from published studies in order to accurately inform patients of the risks. Therefore, the purpose of this study was to systematically review and summarize the existing literature on the complications of strabismus surgery, focusing on the incidence and risk factors of the most common and the
The history of modern strabismus surgery can be traced back to 1839, the year in which Johann Friedrich Diffenbach performed the first successful eye muscle surgery, a medial rectus myotomy in a seven-year-old boy with esotropia.1 Interestingly, that first ‘‘successful’’ strabismus surgery also had the first reported complication, as the patient ended up with a significant overcorrection from the deliberately ‘‘lost’’ medial rectus muscle.2 Since the early days of strabismus surgery, there have been many landmark innovations that have greatly improved the safety and efficacy of eye muscle surgery, including general anesthesia, high-quality suture material, and enhanced visualization with operating loupes and microscopes. However, complications still do occur and it is important for strabismus surgeons and patients to be aware of the risks.
Received 15 May 2014; revised 0 000; accepted 19 June 2014; published online 22 September 2014 Correspondence: David G. Hunter, MD, PhD, Boston Children’s Hospital, Fegan 4, 300 Longwood Ave., Boston, MA 02115, USA. E-mail: [email protected]
421
422 M. J. Wan and D. G. Hunter
RESULTS
most serious complications, and adding in our own clinical experience where appropriate.
The search identified a total of 678 records. Of these, 128 articles were chosen for full text review and 83 of these were ultimately included in the study. The complications addressed in these studies are summarized in Table 1.
MATERIALS AND METHODS
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Search Strategies An electronic search was conducted using the Medline database and the Cochrane Central Register of Controlled Trials (Issue 2, 2014). An initial search of the Medline and Cochrane databases was performed using the keywords (strabismus OR eye muscle) AND (complications OR complication OR injury OR blindness OR vision loss) with the Title/Abstract [tiab] qualifier. Complications related to the administration of local or general anesthetics were not included. A directed search was then conducted for any complication known to the authors but not specifically identified by the initial search strategy. Once articles were reviewed and deemed to be relevant, a recursive search of the reference list of each article was performed.
Study Selection Eligibility criteria was determined a priori by the study authors and included complications resulting from all types of strabismus surgery in both adult and pediatric patient populations. The first author evaluated the title and abstract of all articles identified in the search strategy. Articles with data pertaining to either common complications or rare but serious complications of strabismus surgery were selected for full text review. Any uncertainty about study selection was resolved by consensus with the senior author.
LOCAL COMPLICATIONS Local ocular complications, such as conjunctival injection and scarring, are very common after strabismus surgery and usually have no long-term clinical significance. In a survey of 53 postoperative patients, Escardo´-Paton and Harrad found that conjunctival injection lasted for a median of 10 weeks after strabismus surgery.4 There was a non-significant trend toward longer postoperative conjunctival injection in reoperations and older patients. There was also a large range in the duration of conjunctival injection, including patients who reported persistent redness over six months after surgery.4 Conjunctival scarring is also very common following strabismus surgery and a visible conjunctival scar is present in over 90% of cases posteroperatively.5 Although conjunctival scarring is usually subtle and clinically insignificant, it can rarely be severe, especially after multiple procedures (Figure 1). If conjunctival scarring is severe enough to cause significant restriction or cosmetic deformity, then surgical revision of the scar with a conjunctival autograft or amniotic membrane may be indicated.6 A number of local complications are less common but more likely to require intervention, including dellen, cysts, and pyogenic granulomas. Corneal dellen develop in approximately 3.2 – 4.3% of
TABLE 1. Common and serious complications of strabismus surgery with estimated incidence and risk factors. Complication Conjunctival injection Visible conjunctival scar Corneal Dellen Pyogenic granuloma Slipped muscle Lost muscle Pulled-in-two syndrome Periorbital/orbital cellulitis Scleral perforation Retinal detachment Endophthalmitis Anterior segment ischemia Surgical errors
Key References
Incidence
Risk Factors
100% 90% 3.2–4.3% 2.1% 1 in 1500 1 in 4800 1 in 14,000 1 in 1100–1900 0.4–1.8% 1 in 39,600 1 in 30,000–185,000 1 in 13,300
Duration may be longer with reoperations, older patients Multiple strabismus surgeries Medial rectus muscle procedures, transpositions
1 in 2506
Medial rectus muscle procedures Structurally abnormal extraocular muscle Young patient, sinusitis, eye rubbing, poor hygiene Myopia, recession, children, surgeon inexperience Scleral perforation, vitreous syneresis, older patient Scleral perforation Older patient, operating on 3 or 4 rectus muscles, vascular risk factors, Graves ophthalmopathy Inexperienced surgeon, confusion about deviation/ surgery, torsion, more than one operating room, failing to mark eye
4 5 5, 7 17 19 19 26 42, 43 56–61 63 42, 63 73 85
Seminars in Ophthalmology
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Complications of Stabismus Surgery strabismus surgeries overall, but are much more common after certain procedures, such as medial rectus reoperations (16.3%) and rectus muscle transpositions (18.9%).5,7 Two cases of scleral dellen have also been reported, both with the use of limbal incisions and adjustable sutures.8,9 Although both corneal and scleral dellen typically resolve with conservative treatment, including aggressive lubrication, there is permanent alteration in corneal homogeneity in approximately 20% of cases.7 Cysts, both conjunctival and orbital, are also local complications of strabismus surgery that are uncommon but can be associated with significant adverse effects. The risk factors for cyst formation include younger age and muscle recession procedures.10 Treatment is not always indicated; cysts that are small and asymptomatic may be observed. However, cysts that form early in the postoperative period can become infected, necessitating antibiotic therapy and surgical excision.11,12 Cysts can also form late, sometimes decades after the original surgery, and present as a gradually enlarging mass or recurrent strabismus.13–16 Pyogenic granulomas develop rapidly after surgery and may be quite alarming for patients. In a retrospective review of 472 consecutive patients undergoing strabismus surgery, Espinoza and Lueder found that pyogenic granulomas developed in 2.1% of the cases.17 The majority of pyogenic granulomas resolve completely with topical corticosteroid therapy, and surgical excision is highly effective when conservative therapy fails.17 Other minor anterior complications that can be concerning to patients include retained subconjunctival cilia or non-absorbable suture, darkening of exposed sclera under a recessed muscle (which can be avoided by minimizing excision of Tenon’s), and visibility of the ridge of the original muscle insertion (which is avoided by cutting the muscle flush to sclera).
423
MUSCLE COMPLICATIONS There are several complications of strabismus surgery that involve the extraocular muscles directly, including slipped muscles, lost muscles, stretched scars, incarcerated muscles, and pulled-in-two syndrome. Movement of the vertical extraocular muscles may also cause complications related to eyelid position. Slipped and lost muscles usually present with an inability to rotate the eye beyond midline in the field of action of the affected muscle.18 In the case of a slipped muscle, the capsule remains attached to the sclera, while a lost muscle is characterized by the complete absence of attachments of the muscle and its capsule to the sclera. The British Ophthalmic Surveillance Unit, which reported adverse events from 24,000 strabismus surgeries,19 reported an incidence of 0.067% for slipped muscles (1 in 1500 cases) and 0.02% for lost muscles (1 in 4800 cases). Slipped muscles can usually be retrieved by tracing the path of the capsule posteriorly until the muscle body is found. Lost muscles may be retrievable if there are connective tissue attachments to adjacent extraocular muscles, but finding a lost muscle is not always possible if there are no such attachments, or if the attachments have been dissected intraoperatively.18,20 Stretched scars consist of remodeled amorphous connective tissue that forms between the operated muscle tendon and the sclera. With stretched scars, as opposed to slipped or lost muscles, duction limitations are less severe and the attachment to sclera is readily recognized.21 Often there is a demarcation line where the stretched scar transitions to extraocular muscle. The exact incidence of stretched scars has not been reported; however, Ludwig retrospectively reviewed 134 reoperations in which a stretched scar was discovered and estimated that stretched scar tissue was a contributing factor in 10% of all strabismus reoperations and 50% of late overcorrections.22 To correct the problem, the scar tissue is excised and
FIGURE 1. Postoperative conjunctival scarring. A 52-year-old woman developed consecutive exotropia following bilateral medial rectus muscle recessions as an infant for congenital esotropia. She underwent a left medial rectus resection/advancement of 4.0 mm and a right lateral rectus recession of 6.0 mm with a half-tendon-width superior transposition of both muscles on adjustable sutures. In comparison to preoperative photos of the left eye (a), postoperative photos showed significant medial conjunctival hyperemia and thickening two months after surgery (b). When the conjunctival scarring was still prominent 15 months after surgery (c), she was referred for scar excision with ocular surface reconstruction using amniotic membrane and tissue adhesive. !
2014 Informa Healthcare USA, Inc.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
424 M. J. Wan and D. G. Hunter the muscle reattached to sclera. Ludwig and Chow have stated that the muscle must be fixed to sclera with non-absorbable sutures,21 but in our experience, as long as the scar tissue is fully excised, it is possible to complete the repair with absorbable sutures and an adjustable, hang-back technique. Muscle incarceration can occur during a resection procedure and results from inadequate dissection of adjacent extraocular muscles. The inferior and superior oblique muscles are most commonly incarcerated.23,24 The result can be complex cyclovertical postopererative deviations that can be quite difficult to correct.24 Pulled-in-two syndrome is a rare intraoperative complication of strabismus surgery that occurs when the tension on an extraocular muscle during surgery causes the muscle to rupture, typically several millimeters from the insertion at the muscle-tendon junction.25 A survey of the members of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) estimated the incidence at 1 in 14,000 cases.26 Most reported cases involve patients with preexisting conditions that affect the structural integrity of the extraocular muscles, such as previous strabismus surgery, extraocular muscle palsy, thyroid eye disease, or metastatic infiltration.27–29 However, there have been cases of pulled-in-two syndrome in an ostensibly normal extraocular muscle, usually the inferior rectus muscle.30,31 If the posterior portion of the muscle can be recovered, it can be reattached to the anterior portion of the muscle31 or directly sutured to the sclera in a recessed position.29 Otherwise, a transposition procedure is usually necessary,25,30 but we do not recommend proceeding to transposition until the initial injury has had a chance to heal, as in some cases muscle function recovers beyond what might be expected from the initial intraoperative appearance. The vertical rectus muscles have connective tissue attachments to structures that control eyelid position. Repositioning the rectus muscles can therefore cause an undesirable change in postoperative eyelid appearance.32 In a retrospective review of vertical muscle surgery over a 10-year period, Pacheco et al. found that 91% of patients who had a superior rectus recession developed upper-lid retraction, 94% of patients who had an inferior rectus recession developed lower-lid retraction, and 100% of patients who had an inferior rectus resection developed lower-lid advancement with accompanying flattening.33 Several novel surgical techniques have been developed, primarily for inferior rectus recessions, which may help to minimize the associated changes in eyelid position.34–36
POSTOPERATIVE DIPLOPIA Diplopia after strabismus surgery occurs most commonly when the postoperative alignment is
unsatisfactory.37 This could include undercorrection in visually mature patients with preoperative diplopia due to acquired strabismus, or overcorrection in patients with no preoperative diplopia who have no ability to adapt to the new deviation.38,39 Torsional diplopia following superior oblique weakening procedures can be profound and difficult to correct.40 Postoperative diplopia can also occur, paradoxically, following successful surgical realignment.37 Patients with longstanding constant deviations may develop anomalous retinal correspondence (ARC), in which non-corresponding retinal elements are functionally linked to allow for single binocular vision in the setting of manifest strabismus.41 Successful surgical realignment in patients with ARC may lead to paradoxical diplopia if the patient is unable to either fuse the two images or suppress one of the images. The diplopia in these cases is usually transient, but can rarely be intractable. Kushner performed a retrospective review of 424 adult patients with constant strabismus and no diplopia who underwent prism testing prior to strabismus surgery. While transient diplopia was common in patients who reported diplopia preoperatively with prism testing, the risk of persistent diplopia was only 0.7%.37 The lack of diplopia on preoperative prism testing had a 100% negative predictive value, while the presence of diplopia had a 2% positive predictive value for persistent diplopia. Preoperative prism testing can thus be reassuring to patients when it is negative, but a positive test is not an indication to cancel the procedure. Sensory testing can also be useful to demonstrate the presence of ARC prior to surgery and such patients should be warned that intractable postoperative diplopia is a possible, albeit unlikely, complication.41
PERIOCULAR/ORBITAL CELLULITIS Periocular and orbital infections are rare but potentially sight threatening complications of strabismus surgery. The incidence of postoperative infections has been reported in two retrospective surveys and one prospective study. The retrospective studies included a survey of 63 strabismus surgeons, which found an incidence of 1 per 1900 cases,42 and a survey of the members of AAPOS, which found an incidence of 1 per 1100 cases.43 The lone prospective study, conducted using data from the British Ophthalmic Surveillance Unit, reported an incidence of 1 in 1700 cases.19 While the majority of cases are unilateral and resolve fully with systemic antibiotics,44,45 cases of bilateral orbital cellulitis46 and poor visual outcomes47 have been reported. Young age, unsuspected sinusitis, eye rubbing, and poor hygiene have all been cited as possible risk factors, but definitive data are lacking.43 As a preventative measure, most strabismus surgeons Seminars in Ophthalmology
Complications of Stabismus Surgery prescribe a postoperative course of topical antibiotic-steroid drops; however, there are no conclusive studies demonstrating benefit.48,49 As an alternative, a single dose of topical 5% povidoneiodine at the end of surgery was found to be equivalent to postoperative antibiotic-steroid drops in preventing infectious complications in a retrospective chart review of 1871 patients.50
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
SCLERAL PERFORATION Scleral perforation is one of the most severe and potentially devastating complications of strabismus surgery. The reported incidence of iatrogenic scleral perforation has been steadily decreasing over the past several decades. In studies published in the 1970s, the reported incidence of scleral perforation was between 9.2 and 12.1%.51,52 By the early 1990s, the reported incidence had dropped dramatically to between 1.5% and 2.8%.53,54 Berger and Haase55 compared survey data from different time periods in the same geographical region and found that the incidence of scleral perforation decreased from 3.6% in 1966–1970 to 1.4% in 1989–1993. In the most recent studies, all of which used indirect ophthalmoscopy after pupillary dilation to detect both recognized and unrecognized perforations, scleral perforation rates were between 0.4% and 1.8%.56–59 The declining incidence of scleral perforation is likely the result of several factors, including improved instrumentation, widespread use of high-quality spatulated needles, enhanced visualization with surgical loupes and operating microscopes, and more fellowship-trained strabismus surgeons.60 When performing an initial evaluation on patients who have had prior strabismus surgery, we scrutinize the retinal periphery with extra care in an effort to identify evidence of previous scleral perforation. Although the incidence of scleral perforation is low and decreasing, there are several factors that can increase the risk in a given patient. For instance, the risk is higher when a suture pass is made through thinner sclera, such as in fixed muscle recessions57,61 and in patients with significant myopia and axial elongation.59,60,62 The risk is also higher in younger patients,61 when the surgeon is inexperienced,61 and during reoperations.60 While an isolated scleral perforation does not directly cause permanent visual loss, perforation can lead to retinal detachments and endophthalmitis, both of which carry a high risk of irreversible vision loss or even loss of the eye.19
425
there may or may not be damage to the underlying retina, depending on the depth of the needle pass.56 Even if a retinal hole or tear does occur, the management is controversial because the risk of a subsequent retinal detachment is still quite low. In a survey of 223 surgeons by Simon et al., there were only 14 retinal detachments reported from 728 recognized scleral perforations (1.9%).63 Given that the study included an estimated 554,000 strabismus procedures in total, the incidence of retinal detachment was 1 in 39,600 cases overall. In younger patients with formed vitreous, a retinal detachment is extremely unlikely and animal model studies have suggested that treatment is not superior to observation.64 In older patients or in cases with extensive retinal damage, prophylactic treatment with laser retinopexy is likely warranted.65
ENDOPHTHALMITIS Although exceedingly rare, postoperative endophthalmitis is often catastrophic when it does occur. Survey data have suggested that the incidence of endophthalmitis after strabismus surgery is in the range of 1 in 30,000 to 185,000 cases.42,63 Even with recognized scleral perforation, endophthalmitis is still very uncommon, occurring in only 0.4% of known perforations.63 There is an ongoing debate about whether scleral perforation is a necessary prerequisite for endophthalmitis to develop, as there have been 11 reported cases with no known scleral perforation.66–70 Pathological examination of enucleated specimens was conducted in four of the 11 cases; two showed microscopic evidence of iatrogenic scleral perforation while the other two did not.66,67 Other postulated mechanisms for postoperative endophthalmitis include endogenous seeding and intraocular progression from a localized abscess of the sclera.67,71 While there is no conclusive evidence for either of these alternative mechanisms, in two of the six cases reported by Recchia et al., the affected patients were diagnosed with sepsis prior to being diagnosed with endophthalmitis, suggesting the possibility of intraocular seeding from a systemic source.67 The outcome of endophthalmitis is very poor overall, and most affected eyes become blind and phthisical, often requiring enucleation.66,67 Despite the dismal prognosis, early recognition and aggressive treatment is still crucial as there have been several reported cases with good visual outcomes.68,70,72
ANTERIOR SEGMENT ISCHEMIA RETINAL DETACHMENT While an iatrogenic scleral perforation typically causes damage to the immediately adjacent choroid, !
2014 Informa Healthcare USA, Inc.
Anterior segment ischemia is an uncommon but wellestablished complication of strabismus surgery. A survey of the members of AAPOS revealed 30 cases of
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
426 M. J. Wan and D. G. Hunter anterior segment ischemia from an estimated total of 400,000 strabismus procedures (1 in 13,300 cases).73 However, this is likely a significant underestimate because many mild cases resolve spontaneously.74 The risk of anterior segment ischemia is influenced by both patient susceptibility and the extent of the strabismus surgery. The most important patient risk factor is older age;75 other reported risk factors include atherosclerosis, blood dyscrasias, hyperviscosity syndromes, carotid artery ligation, and Graves ophthalmopathy.76–78 Prior eye muscle surgeries and the extent of the strabismus surgery also play a significant role, as the vast majority of reported cases involve operating on three or four rectus muscles, simultaneously or staged, in the same eye.79 Microvascular dissection with preservation of the anterior ciliary vessels during strabismus surgery may help to prevent anterior segment ischemia, but does not eliminate the risk entirely.80 Muscle plication, as an alternative to resection, has also been utilized in an effort to preserve ciliary vasculature.81 In patients at high risk of anterior segment ischemia, preoperative anterior segment fluorescein angiography may be useful to assess the state of the anterior circulation and better define the risk prior to undergoing strabismus surgery.82–84
DISCUSSION Like all surgical procedures, strabismus surgery carries a number of risks and potential complications. Common complications, such as conjunctival injection, scarring, dellen, cysts, and pyogenic granulomas, usually resolve with conservative management and time. Serious complications, such as slipped muscles, lost muscles, stretched scars, incarcerated muscles, pulled-in-two syndrome, scleral perforations, retinal detachments, endophthalmitis, periocular infections, and anterior segment ischemia, are uncommon, but often need more definitive intervention and carry a significant risk of permanent sequelae. Finally, strabismus surgery has a number of distinctive features that can predispose surgeons to making surgical errors. It is critical for strabismus surgeons, and all members of the surgical team, to remain constantly vigilant about the risk of errors and to adhere to the systems designed to prevent such errors from occurring. While strabismus surgeons can take precautions to minimize the probability of surgical errors and complications, the risks cannot be eliminated entirely, and it is important for both strabismus surgeons and patients to be aware of the risks when planning, performing, and recovering from surgery.
SURGICAL ERRORS There are features specific to strabismus surgery that may increase the risk of surgical errors.85 For instance, strabismus surgery is often performed on multiple muscles in one or both eyes and several terms are easily confused, such as esotropia/exotropia, hypertropia/hypotropia, adduction/abduction, and recession/resection. Based on a systematic review, the surgical error rate for all surgical specialties was estimated to be between 0.09 to 4.5 errors per 10,000 cases.86 For strabismus surgery, a survey of 517 strabismus surgeons found that 33.5% of the respondents had made a surgical error at some point during their career with an overall incidence of 1 in 2506 cases (4.0 errors per 10,000 cases).85 Errors included operating on the wrong eye, wrong patient, or wrong muscle (e.g., inferior rectus muscle instead of inferior oblique or medial rectus muscle), or performing the wrong procedure.85 The risk was higher with inexperienced surgeons, confusion about the underlying deviation or surgical plan, ocular torsion, operating in more than one room on the same day, or failing to mark the eye in unilateral cases. Based on the findings of the study, the authors recommended several preoperative steps to reduce the risk of surgical errors, including preoperative verification of ocular misalignment, site marking, and performing a preoperative ‘‘time out’’ that includes the deviation, specific muscles to be operated on, and the intended procedure.
DECLARATION OF INTEREST The first author, Michael Wan, has no financial disclosures or conflicts. The senior author, Dr. David G Hunter, has the following financial disclosures: (1) Boston Children’s Hospital: Patent; (2) Johns Hopkins University: Patent; (3) Lippincott Williams Wilkins: Book royalties; (4) Slack, Inc: Book royalties; (5) REBIScan, Inc: Consultant, equity owner. None of these are referred to in the manuscript or apply directly to the content.
REFERENCES 1. Remy C, Aracil P. History of strabismus surgery. J Fr Ophtalmol 1984;7(6–7):493–498. 2. Helveston EM. Surgical Management of Strabismus: A Practical and Updated Approach, 5th ed. Oostende, Belgium: Wayenborgh Publishing, 2005. 3. Approved by the Board of Trustees, American Academy of Ophthalmology. Practice guidelines for informed consent. The American Academy of Ophthalmology 2011:1–6. 4. Escardo´-Paton JA, Harrad RA. Duration of conjunctival redness following adult strabismus surgery. J AAPOS 2009; 13(6):583–586. 5. Scharwey K, Gra¨f M, Becker R, Kaufmann H. Healing process and complications after eye muscle surgery. Ophthalmologe 2000;97(1):22–26. 6. Leoson Y, Øgard C, Mortzos P. Conjunctival autograft as treatment for anterior displacement and scarring of the plica Seminars in Ophthalmology
Complications of Stabismus Surgery
7. 8. 9.
10.
11.
12.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
13.
14.
15.
16.
17.
18. 19. 20.
21. 22. 23.
24. 25.
26.
27.
28.
29.
!
semilunaris after strabismus surgery. J AAPOS 2013; 17(5):528–529. Fresina M, Campos EC. Corneal ‘‘dellen’’ as a complication of strabismus surgery. Eye (Lond) 2009;23(1):161–163. Perez I. The ‘‘scleral dellen,’’ a complication of adjustable strabismus surgery. J AAPOS 2002;6(5):2–2. Lee DH, Herion MA, Unwin DR, Cruz OA. Scleral dellen after bilateral adjustable suture medial rectus muscle resection. J AAPOS 2003;7(3):221–222. Guadilla AM, de Lian˜o PG, Merino P, Franco G. Conjunctival cysts as a complication after strabismus surgery. J Pediatr Ophthalmol Strabismus 2011;48(5):298–300. Khan AO, Al-Katan H, Al-Baharna I, Al-Wadani F. Infected epithelial inclusion cyst mimicking subconjunctival abscess after strabismus surgery. J AAPOS 2007;11(3):303–304. Kushner BJ. Subconjunctival cysts as a complication of strabismus surgery. Arch Ophthalmol 1992;110(9):1243–1245. Curtis TH, Stout AU, Drack AV, Durairaj VD. Giant orbital cysts after strabismus surgery. Am J Ophthalmol 2006; 142(4):697–699. Song JJ, Finger PT, Kurli M, Wisnicki HJ, Iacob CE. Giant secondary conjunctival inclusion cysts: A late complication of strabismus surgery. Ophthalmology 2006; 113(6):1045–1052. Ullrich CR, Garola RE, Cibis GW. Bilateral extraocular muscle epithelial inclusion cysts as a complication of strabismus surgery. J AAPOS 2003;7(5):366–367. Lally DR, Eagle RC, Wasserman BN. Occult intraorbital conjunctival inclusion cyst discovered almost 70 years after strabismus surgery. J Pediatr Ophthalmol Strabismus 2013;50 Online:e15–7. Espinoza GM, Lueder GT. Conjunctival pyogenic granulomas after strabismus surgery. Ophthalmology 2005; 112(7):1283–1286. Lenart TD, Lambert SR. Slipped and lost extraocular muscles. Ophthalmol Clin North Am 2001;14(3):433–442. Bradbury JA, Taylor RH. Severe complications of strabismus surgery. J AAPOS 2013;17(1):59–63. Plager DA, Parks MM. Recognition and repair of the ‘‘lost’’ rectus muscle: A report of 25 cases. Ophthalmology 1990; 97(1):131–136; discussion 136–7. Ludwig IH, Chow AY. Scar remodeling after strabismus surgery. J AAPOS 2000;4(6):326–333. Ludwig IH. Scar remodeling after strabismus surgery. Trans Am Ophthalmol Soc 1999;97:583–651. Helveston EM, Alcorn DM, Ellis FD. Inferior oblique inclusion after lateral rectus surgery. Graefes Arch Clin Exp Ophthalmol 1988;226(2):102–105. Kushner BJ. Superior oblique tendon incarceration syndrome. Arch Ophthalmol 2007;125(8):1070–1076. Aguirre-Aquino BI, Riemann CD, Lewis H, Traboulsi EI. Anterior transposition of the inferior oblique muscle as the initial treatment of a snapped inferior rectus muscle. J AAPOS 2001;5(1):52–54. Erzurum SA, Greenwald MJ. The Pulled-in-Two Syndrome: A survey of AAPO&S Members. Proceedings of the 1991 Meeting of the American Association of Pediatric Ophthalmology and Strabismus. Montreal, Canada, May 15–19, 1991. Wallace DK, Virata SR, Mukherji SK. Strabismus surgery complicated by ‘‘pulled in two syndrome’’ in a case of breast carcinoma metastatic to the medial rectus muscle. J AAPOS 2000;4(2):117–119. Dunbar JA, Lueder GT. Intraoperative dehiscence of a rectus muscle: Report of two cases. J AAPOS 1997; 1(3):175–177. MacEwen CJ, Lee JP, Fells P. Aetiology and management of the ‘‘detached’’ rectus muscle. Br J Ophthalmol 1992; 76(3):131–136.
2014 Informa Healthcare USA, Inc.
427
30. Kowal LL, Wutthiphan SS, McKelvie PP. The snapped inferior rectus. Aust N Z J Ophthalmol 1998; 26(1):29–35. 31. Akbari MR, Jafari AK, Ameri A, Anvari F, Eshraghi B, Masoomian B. Successful extraocular muscle re-resection for a strabismus surgery complication: A ‘‘snapped’’ [severed, inadvertently] and retrieved inferior rectus muscle: A case report. Binocul Vis Strabolog Q Simms Romano 2012;27(1):41–45. 32. Callahan MA. Surgically mismanaged ptosis associated with double elevator palsy. Arch Ophthalmol 1981; 99(1):108–112. 33. Pacheco EM, Guyton DL, Repka MX. Changes in eyelid position accompanying vertical rectus muscle surgery and prevention of lower lid retraction with adjustable surgery. J Pediatr Ophthalmol Strabismus 1992; 29(5):265–272. 34. Gokyigit B, Akar S, Yilmaz OF. A novel technique for inferior rectus recession. Clin Ophthalmol 2014;8:263–269. 35. Akbari MR, Raygan F, Ameri A, et al. Lower eyelid retractor lysis versus Lockwood advancement to minimize lower eyelid retraction resulting from inferior rectus muscle recession. J AAPOS 2013;17(4):445–447. 36. Liao SL, Shih MJ, Lin LL-K. A procedure to minimize lower lid retraction during large inferior rectus recession in Graves ophthalmopathy. Am J Ophthalmol 2006; 141(2):340–345. 37. Kushner BJ. Intractable diplopia after strabismus surgery in adults. Arch Ophthalmol 2002;120(11):1498–1504. 38. Pratt-Johnson JA, Tillson G. Suppression in strabismus: An update. Br J Ophthalmol 1984;68(3):174–178. 39. Simon JW, Paskowski JR. Intractable diplopia after overcorrection of vertical strabismus. Am J Ophthalmol 1994; 117(5):675–676. 40. Santiago AP, Rosenbaum AL. Grave complications after superior oblique tenotomy or tenectomy for Brown syndrome. J AAPOS 1997;1(1):8–15. 41. Castleberry C, Arnoldi K. Predicting postoperative paradoxical diplopia. Am Orthopt J 2003;53:88–97. 42. Ing MR. Infection following strabismus surgery. Ophthalmic Surg 1991;22(1):41–43. 43. Kivlin JD, Wilson ME. Periocular infection after strabismus surgery: The Periocular Infection Study Group. J Pediatr Ophthalmol Strabismus 1995;32(1):42–49. 44. Lau FHS, Leung TF, Fan DSP. An unusual complication after strabismus surgery. Hong Kong Med J 2009;15(4): 297–298. 45. Armesto A, Ugrin MC. Orbital cellulitis after faden operation on the medial rectus. Strabismus 2007;15(4): 215–219. 46. Basheikh A, Superstein R. A child with bilateral orbital cellulitis one day after strabismus surgery. J AAPOS 2009; 13(5):488–490. 47. Hoyama E, Limawararut V, Leibovitch I, et al. Blinding orbital cellulitis: A complication of strabismus surgery. Ophthal Plast Reconstr Surg 2006;22(6):472–473. 48. Wilson ME. Topical antibiotic/steroid medication for infection prophylaxis after strabismus surgery: Is it custom or science? J AAPOS 2008;12(4):321–321. 49. Wortham E, Anandakrishnan I, Kraft SP, et al. Are antibiotic-steroid drops necessary following strabismus surgery? A prospective, randomized, masked trial. J Pediatr Ophthalmol Strabismus 1990;27(4):205–207. 50. Koederitz NM, Neely DE, Plager DA, et al. Postoperative povidone-iodine prophylaxis in strabismus surgery. J AAPOS 2008;12(4):396–400. 51. Gottlieb F, Castro JL. Perforation of the globe during strabismus surgery. Arch Ophthalmol 1970;84(2): 151–157.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
428 M. J. Wan and D. G. Hunter 52. Kaluzny J, Ralcewicz H, Perlikiewicz-Kikielowa A. Eye fundus periphery after operation for squint (author’s transl). Klin Oczna 1977;47(12):557–558. 53. Morris RJ, Rosen PH, Fells P. Incidence of inadvertent globe perforation during strabismus surgery. Br J Ophthalmol 1990;74(8):490–493. 54. Cibis GW. Incidence of inadvertent perforation in strabismus surgery. Ophthalmic Surg 1992;23(5):360–361. 55. Berger RW, Haase W. Original papers: Complications in strabismus surgery. Strabismus 1997;5(2):67–72. 56. Noel LP, Bloom JN, Clarke WN, Bawazeer A. Retinal perforation in strabismus surgery. J Pediatr Ophthalmol Strabismus 1997;34(2):115–117. 57. Surachatkumtonekul T, Phamonvaechavan P, Kumpanardsanyakorn S, et al. Scleral penetrations and perforations in strabismus surgery: Incidence, risk factors and sequelae. J Med Assoc Thai 2009;92(11):1463–1469. 58. Taherian K, Sharma P, Prakash P, Azad R. Scleral perforations in strabismus surgery: Incidence and role of prophylactic cryotherapy: A clinical and experimental study. Strabismus 2004;12(1):17–25. 59. Park K, Hong S, Chung W, et al. Inadvertent scleral perforation after strabismus surgery: Incidence and association with refractive error. Can J Ophthalmol 2008; 43(6):669–672. 60. Awad AH, Mullaney PB, Al-Hazmi A, et al. Recognized globe perforation during strabismus surgery: Incidence, risk factors, and sequelae. J AAPOS 2000;4(3):150–153. 61. Dang Y, Racu C, Isenberg SJ. Scleral penetrations and perforations in strabismus surgery and associated risk factors. J AAPOS 2004;8(4):325–331. 62. Haugen OH, Kjeka O. Localized, extreme scleral thinning causing globe rupture during strabismus surgery. J AAPOS 2005;9(6):595–596. 63. Simon JW, Lininger LL, Scheraga JL. Recognized scleral perforation during eye muscle surgery: Incidence and sequelae. J Pediatr Ophthalmol Strabismus 1992; 29(5):273–275. 64. Bagheri A, Erfanian-Salim R, Ahmadieh H, et al. Globe perforation during strabismus surgery in an animal model: Treatment versus observation. J AAPOS 2011;15(2):144–147. 65. Sprunger DT, Klapper SR, Bonnin JM, Minturn JT. Management of experimental globe perforation during strabismus surgery. J Pediatr Ophthalmol Strabismus 1996; 33(3):140–143. 66. Huang S, Crawford JB, Rutar T. Pathological findings in poststrabismus surgery endophthalmitis. J AAPOS 2011; 15(1):98–100. 67. Recchia FM, Baumal CR, Sivalingam A, et al. Endophthalmitis after pediatric strabismus surgery. Arch Ophthalmol 2000;118(7):939–944. 68. Lenahan DS, Kutschke PJ, Scott WE. Endophthalmitis following pediatric strabismus surgery with good visual result. Am Orthopt J 2004;54:152–154.
69. Thomas JW, Hamill MB, Lambert HM. Streptococcus pneumoniae endophthalmitis following strabismus surgery. Arch Ophthalmol 1993;111(9):1170–1171. 70. Kushner BJ, Meyers FL. Good visual outcome after endophthalmitis in an eye previously treated successfully for amblyopia. J Pediatr Ophthalmol Strabismus 1989; 26(2):69–71. 71. Rosenbaum AL. Endophthalmitis after strabismus surgery. Arch Ophthalmol 2000;118(7):982–983. 72. Walton RC, Cohen AS. Staphylococcus epidermidisendophthalmitis following strabismus surgery. J AAPOS 2004;8(6):592–593. 73. France TD, Simon JW. Anterior segment ischemia syndrome following muscle surgery: The AAPO&S experience. J Pediatr Ophthalmol Strabismus 1986;23(2):87–91. 74. Saunders RA, Sandall GS. Anterior segment ischemia syndrome following rectus muscle transposition. Am J Ophthalmol 1982;93(1):34–38. 75. Bleik JH, Cherfan GM. Anterior segment ischemia after the Jensen procedure in a 10-year-old patient. Am J Ophthalmol 1995;119(4):524–525. 76. Saunders RA, Bluestein EC, Wilson ME, Berland JE. Anterior segment ischemia after strabismus surgery. Surv Ophthalmol 1994;38(5):456–466. 77. Jacobs DS, Vastine DW, Urist MJ. Anterior segment ischemia and sector iris atrophy: After strabismus surgery in a patient with chronic lymphocytic leukemia. Ophthalmic Surg 1976;7(4):42–48. 78. Wolf E, Wagner RS, Zarbin MA. Anterior segment ischemia and retinal detachment after vertical rectus muscle surgery. Eur J Ophthalmol 2000;10(1):82–87. 79. Saunders RA, Phillips MS. Anterior segment ischemia after three rectus muscle surgery. Ophthalmology 1988; 95(4):533–537. 80. Murdock TJ, Mills MD. Anterior segment ischemia after strabismus surgery with microvascular dissection. J AAPOS 2000;4(1):56–57. 81. Velez FG, Demer JL, Pihlblad MS, Pineles SL. Rectus muscle plication using an adjustable suture technique. J AAPOS 2013;17(5):480–483. 82. Kaeser P-F, Klainguti G. Anterior segment angiography in strabismus surgery. Klin Monbl Augenheilkd 2012; 229(4):362–364. 83. Hayreh SS, Scott WE. Fluorescein iris angiography. I. Normal pattern. Arch Ophthalmol 1978; 96(8):1383–1389. 84. Hayreh SS, Scott WE. Fluorescein iris angiography. II. Disturbances in iris circulation following strabismus operation on the various recti. Arch Ophthalmol 1978; 96(8):1390–1400. 85. Shen E, Porco T, Rutar T. Errors in strabismus surgery. JAMA Ophthalmol 2013;131(1):75–79. 86. Devine J, Chutkan N, Norvell DC, Dettori JR. Avoiding wrong site surgery: A systematic review. Spine 2010;35(Suppl 9):S28–S36.
Seminars in Ophthalmology
REVIEW
Complications of Strabismus Surgery: Incidence and Risk Factors Michael J. Wan and David G. Hunter
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Department of Ophthalmology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts, USA
ABSTRACT Purpose: To perform a systematic review of the complications of strabismus surgery, focusing on incidence and risk factors. Material and Methods: A systematic literature search was performed using the Medline and Cochrane databases. Results: Local complications, such as conjunctival injection and mild scarring, are almost universal but only rarely have long-term clinical significance. There are several important complications that are uncommon but associated with significant long-term sequelae, including slipped muscles, lost muscles, stretched scars, incarcerated muscles, pulled-in-two syndrome, periocular infections, orbital cellulitis, scleral perforations, retinal detachments, endophthalmitis, anterior segment ischemia, and surgical errors. Discussion: Strabismus surgery is associated with a number of common and serious complications, and it is important for both surgeons and patients to be aware of the risks. Keywords: Complications, postoperative, review, strabismus, surgery
INTRODUCTION
When consenting patients for strabismus surgery, it is incumbent on ophthalmologists to know the approximate incidence of potential complications and the various factors that may increase the risk in a given patient. According to the American Academy of Ophthalmology (AAO), physicians must disclose ‘‘any risks or potential complications that are sufficiently common or significant that they might reasonably influence the patient’s decision to accept the proposed procedure.’’3 Since a large number of ophthalmologists will not personally encounter many of the rare complications of strabismus surgery, it is necessary to derive the incidence of such complications from published studies in order to accurately inform patients of the risks. Therefore, the purpose of this study was to systematically review and summarize the existing literature on the complications of strabismus surgery, focusing on the incidence and risk factors of the most common and the
The history of modern strabismus surgery can be traced back to 1839, the year in which Johann Friedrich Diffenbach performed the first successful eye muscle surgery, a medial rectus myotomy in a seven-year-old boy with esotropia.1 Interestingly, that first ‘‘successful’’ strabismus surgery also had the first reported complication, as the patient ended up with a significant overcorrection from the deliberately ‘‘lost’’ medial rectus muscle.2 Since the early days of strabismus surgery, there have been many landmark innovations that have greatly improved the safety and efficacy of eye muscle surgery, including general anesthesia, high-quality suture material, and enhanced visualization with operating loupes and microscopes. However, complications still do occur and it is important for strabismus surgeons and patients to be aware of the risks.
Received 15 May 2014; revised 0 000; accepted 19 June 2014; published online 22 September 2014 Correspondence: David G. Hunter, MD, PhD, Boston Children’s Hospital, Fegan 4, 300 Longwood Ave., Boston, MA 02115, USA. E-mail: [email protected]
421
422 M. J. Wan and D. G. Hunter
RESULTS
most serious complications, and adding in our own clinical experience where appropriate.
The search identified a total of 678 records. Of these, 128 articles were chosen for full text review and 83 of these were ultimately included in the study. The complications addressed in these studies are summarized in Table 1.
MATERIALS AND METHODS
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Search Strategies An electronic search was conducted using the Medline database and the Cochrane Central Register of Controlled Trials (Issue 2, 2014). An initial search of the Medline and Cochrane databases was performed using the keywords (strabismus OR eye muscle) AND (complications OR complication OR injury OR blindness OR vision loss) with the Title/Abstract [tiab] qualifier. Complications related to the administration of local or general anesthetics were not included. A directed search was then conducted for any complication known to the authors but not specifically identified by the initial search strategy. Once articles were reviewed and deemed to be relevant, a recursive search of the reference list of each article was performed.
Study Selection Eligibility criteria was determined a priori by the study authors and included complications resulting from all types of strabismus surgery in both adult and pediatric patient populations. The first author evaluated the title and abstract of all articles identified in the search strategy. Articles with data pertaining to either common complications or rare but serious complications of strabismus surgery were selected for full text review. Any uncertainty about study selection was resolved by consensus with the senior author.
LOCAL COMPLICATIONS Local ocular complications, such as conjunctival injection and scarring, are very common after strabismus surgery and usually have no long-term clinical significance. In a survey of 53 postoperative patients, Escardo´-Paton and Harrad found that conjunctival injection lasted for a median of 10 weeks after strabismus surgery.4 There was a non-significant trend toward longer postoperative conjunctival injection in reoperations and older patients. There was also a large range in the duration of conjunctival injection, including patients who reported persistent redness over six months after surgery.4 Conjunctival scarring is also very common following strabismus surgery and a visible conjunctival scar is present in over 90% of cases posteroperatively.5 Although conjunctival scarring is usually subtle and clinically insignificant, it can rarely be severe, especially after multiple procedures (Figure 1). If conjunctival scarring is severe enough to cause significant restriction or cosmetic deformity, then surgical revision of the scar with a conjunctival autograft or amniotic membrane may be indicated.6 A number of local complications are less common but more likely to require intervention, including dellen, cysts, and pyogenic granulomas. Corneal dellen develop in approximately 3.2 – 4.3% of
TABLE 1. Common and serious complications of strabismus surgery with estimated incidence and risk factors. Complication Conjunctival injection Visible conjunctival scar Corneal Dellen Pyogenic granuloma Slipped muscle Lost muscle Pulled-in-two syndrome Periorbital/orbital cellulitis Scleral perforation Retinal detachment Endophthalmitis Anterior segment ischemia Surgical errors
Key References
Incidence
Risk Factors
100% 90% 3.2–4.3% 2.1% 1 in 1500 1 in 4800 1 in 14,000 1 in 1100–1900 0.4–1.8% 1 in 39,600 1 in 30,000–185,000 1 in 13,300
Duration may be longer with reoperations, older patients Multiple strabismus surgeries Medial rectus muscle procedures, transpositions
1 in 2506
Medial rectus muscle procedures Structurally abnormal extraocular muscle Young patient, sinusitis, eye rubbing, poor hygiene Myopia, recession, children, surgeon inexperience Scleral perforation, vitreous syneresis, older patient Scleral perforation Older patient, operating on 3 or 4 rectus muscles, vascular risk factors, Graves ophthalmopathy Inexperienced surgeon, confusion about deviation/ surgery, torsion, more than one operating room, failing to mark eye
4 5 5, 7 17 19 19 26 42, 43 56–61 63 42, 63 73 85
Seminars in Ophthalmology
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
Complications of Stabismus Surgery strabismus surgeries overall, but are much more common after certain procedures, such as medial rectus reoperations (16.3%) and rectus muscle transpositions (18.9%).5,7 Two cases of scleral dellen have also been reported, both with the use of limbal incisions and adjustable sutures.8,9 Although both corneal and scleral dellen typically resolve with conservative treatment, including aggressive lubrication, there is permanent alteration in corneal homogeneity in approximately 20% of cases.7 Cysts, both conjunctival and orbital, are also local complications of strabismus surgery that are uncommon but can be associated with significant adverse effects. The risk factors for cyst formation include younger age and muscle recession procedures.10 Treatment is not always indicated; cysts that are small and asymptomatic may be observed. However, cysts that form early in the postoperative period can become infected, necessitating antibiotic therapy and surgical excision.11,12 Cysts can also form late, sometimes decades after the original surgery, and present as a gradually enlarging mass or recurrent strabismus.13–16 Pyogenic granulomas develop rapidly after surgery and may be quite alarming for patients. In a retrospective review of 472 consecutive patients undergoing strabismus surgery, Espinoza and Lueder found that pyogenic granulomas developed in 2.1% of the cases.17 The majority of pyogenic granulomas resolve completely with topical corticosteroid therapy, and surgical excision is highly effective when conservative therapy fails.17 Other minor anterior complications that can be concerning to patients include retained subconjunctival cilia or non-absorbable suture, darkening of exposed sclera under a recessed muscle (which can be avoided by minimizing excision of Tenon’s), and visibility of the ridge of the original muscle insertion (which is avoided by cutting the muscle flush to sclera).
423
MUSCLE COMPLICATIONS There are several complications of strabismus surgery that involve the extraocular muscles directly, including slipped muscles, lost muscles, stretched scars, incarcerated muscles, and pulled-in-two syndrome. Movement of the vertical extraocular muscles may also cause complications related to eyelid position. Slipped and lost muscles usually present with an inability to rotate the eye beyond midline in the field of action of the affected muscle.18 In the case of a slipped muscle, the capsule remains attached to the sclera, while a lost muscle is characterized by the complete absence of attachments of the muscle and its capsule to the sclera. The British Ophthalmic Surveillance Unit, which reported adverse events from 24,000 strabismus surgeries,19 reported an incidence of 0.067% for slipped muscles (1 in 1500 cases) and 0.02% for lost muscles (1 in 4800 cases). Slipped muscles can usually be retrieved by tracing the path of the capsule posteriorly until the muscle body is found. Lost muscles may be retrievable if there are connective tissue attachments to adjacent extraocular muscles, but finding a lost muscle is not always possible if there are no such attachments, or if the attachments have been dissected intraoperatively.18,20 Stretched scars consist of remodeled amorphous connective tissue that forms between the operated muscle tendon and the sclera. With stretched scars, as opposed to slipped or lost muscles, duction limitations are less severe and the attachment to sclera is readily recognized.21 Often there is a demarcation line where the stretched scar transitions to extraocular muscle. The exact incidence of stretched scars has not been reported; however, Ludwig retrospectively reviewed 134 reoperations in which a stretched scar was discovered and estimated that stretched scar tissue was a contributing factor in 10% of all strabismus reoperations and 50% of late overcorrections.22 To correct the problem, the scar tissue is excised and
FIGURE 1. Postoperative conjunctival scarring. A 52-year-old woman developed consecutive exotropia following bilateral medial rectus muscle recessions as an infant for congenital esotropia. She underwent a left medial rectus resection/advancement of 4.0 mm and a right lateral rectus recession of 6.0 mm with a half-tendon-width superior transposition of both muscles on adjustable sutures. In comparison to preoperative photos of the left eye (a), postoperative photos showed significant medial conjunctival hyperemia and thickening two months after surgery (b). When the conjunctival scarring was still prominent 15 months after surgery (c), she was referred for scar excision with ocular surface reconstruction using amniotic membrane and tissue adhesive. !
2014 Informa Healthcare USA, Inc.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
424 M. J. Wan and D. G. Hunter the muscle reattached to sclera. Ludwig and Chow have stated that the muscle must be fixed to sclera with non-absorbable sutures,21 but in our experience, as long as the scar tissue is fully excised, it is possible to complete the repair with absorbable sutures and an adjustable, hang-back technique. Muscle incarceration can occur during a resection procedure and results from inadequate dissection of adjacent extraocular muscles. The inferior and superior oblique muscles are most commonly incarcerated.23,24 The result can be complex cyclovertical postopererative deviations that can be quite difficult to correct.24 Pulled-in-two syndrome is a rare intraoperative complication of strabismus surgery that occurs when the tension on an extraocular muscle during surgery causes the muscle to rupture, typically several millimeters from the insertion at the muscle-tendon junction.25 A survey of the members of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) estimated the incidence at 1 in 14,000 cases.26 Most reported cases involve patients with preexisting conditions that affect the structural integrity of the extraocular muscles, such as previous strabismus surgery, extraocular muscle palsy, thyroid eye disease, or metastatic infiltration.27–29 However, there have been cases of pulled-in-two syndrome in an ostensibly normal extraocular muscle, usually the inferior rectus muscle.30,31 If the posterior portion of the muscle can be recovered, it can be reattached to the anterior portion of the muscle31 or directly sutured to the sclera in a recessed position.29 Otherwise, a transposition procedure is usually necessary,25,30 but we do not recommend proceeding to transposition until the initial injury has had a chance to heal, as in some cases muscle function recovers beyond what might be expected from the initial intraoperative appearance. The vertical rectus muscles have connective tissue attachments to structures that control eyelid position. Repositioning the rectus muscles can therefore cause an undesirable change in postoperative eyelid appearance.32 In a retrospective review of vertical muscle surgery over a 10-year period, Pacheco et al. found that 91% of patients who had a superior rectus recession developed upper-lid retraction, 94% of patients who had an inferior rectus recession developed lower-lid retraction, and 100% of patients who had an inferior rectus resection developed lower-lid advancement with accompanying flattening.33 Several novel surgical techniques have been developed, primarily for inferior rectus recessions, which may help to minimize the associated changes in eyelid position.34–36
POSTOPERATIVE DIPLOPIA Diplopia after strabismus surgery occurs most commonly when the postoperative alignment is
unsatisfactory.37 This could include undercorrection in visually mature patients with preoperative diplopia due to acquired strabismus, or overcorrection in patients with no preoperative diplopia who have no ability to adapt to the new deviation.38,39 Torsional diplopia following superior oblique weakening procedures can be profound and difficult to correct.40 Postoperative diplopia can also occur, paradoxically, following successful surgical realignment.37 Patients with longstanding constant deviations may develop anomalous retinal correspondence (ARC), in which non-corresponding retinal elements are functionally linked to allow for single binocular vision in the setting of manifest strabismus.41 Successful surgical realignment in patients with ARC may lead to paradoxical diplopia if the patient is unable to either fuse the two images or suppress one of the images. The diplopia in these cases is usually transient, but can rarely be intractable. Kushner performed a retrospective review of 424 adult patients with constant strabismus and no diplopia who underwent prism testing prior to strabismus surgery. While transient diplopia was common in patients who reported diplopia preoperatively with prism testing, the risk of persistent diplopia was only 0.7%.37 The lack of diplopia on preoperative prism testing had a 100% negative predictive value, while the presence of diplopia had a 2% positive predictive value for persistent diplopia. Preoperative prism testing can thus be reassuring to patients when it is negative, but a positive test is not an indication to cancel the procedure. Sensory testing can also be useful to demonstrate the presence of ARC prior to surgery and such patients should be warned that intractable postoperative diplopia is a possible, albeit unlikely, complication.41
PERIOCULAR/ORBITAL CELLULITIS Periocular and orbital infections are rare but potentially sight threatening complications of strabismus surgery. The incidence of postoperative infections has been reported in two retrospective surveys and one prospective study. The retrospective studies included a survey of 63 strabismus surgeons, which found an incidence of 1 per 1900 cases,42 and a survey of the members of AAPOS, which found an incidence of 1 per 1100 cases.43 The lone prospective study, conducted using data from the British Ophthalmic Surveillance Unit, reported an incidence of 1 in 1700 cases.19 While the majority of cases are unilateral and resolve fully with systemic antibiotics,44,45 cases of bilateral orbital cellulitis46 and poor visual outcomes47 have been reported. Young age, unsuspected sinusitis, eye rubbing, and poor hygiene have all been cited as possible risk factors, but definitive data are lacking.43 As a preventative measure, most strabismus surgeons Seminars in Ophthalmology
Complications of Stabismus Surgery prescribe a postoperative course of topical antibiotic-steroid drops; however, there are no conclusive studies demonstrating benefit.48,49 As an alternative, a single dose of topical 5% povidoneiodine at the end of surgery was found to be equivalent to postoperative antibiotic-steroid drops in preventing infectious complications in a retrospective chart review of 1871 patients.50
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
SCLERAL PERFORATION Scleral perforation is one of the most severe and potentially devastating complications of strabismus surgery. The reported incidence of iatrogenic scleral perforation has been steadily decreasing over the past several decades. In studies published in the 1970s, the reported incidence of scleral perforation was between 9.2 and 12.1%.51,52 By the early 1990s, the reported incidence had dropped dramatically to between 1.5% and 2.8%.53,54 Berger and Haase55 compared survey data from different time periods in the same geographical region and found that the incidence of scleral perforation decreased from 3.6% in 1966–1970 to 1.4% in 1989–1993. In the most recent studies, all of which used indirect ophthalmoscopy after pupillary dilation to detect both recognized and unrecognized perforations, scleral perforation rates were between 0.4% and 1.8%.56–59 The declining incidence of scleral perforation is likely the result of several factors, including improved instrumentation, widespread use of high-quality spatulated needles, enhanced visualization with surgical loupes and operating microscopes, and more fellowship-trained strabismus surgeons.60 When performing an initial evaluation on patients who have had prior strabismus surgery, we scrutinize the retinal periphery with extra care in an effort to identify evidence of previous scleral perforation. Although the incidence of scleral perforation is low and decreasing, there are several factors that can increase the risk in a given patient. For instance, the risk is higher when a suture pass is made through thinner sclera, such as in fixed muscle recessions57,61 and in patients with significant myopia and axial elongation.59,60,62 The risk is also higher in younger patients,61 when the surgeon is inexperienced,61 and during reoperations.60 While an isolated scleral perforation does not directly cause permanent visual loss, perforation can lead to retinal detachments and endophthalmitis, both of which carry a high risk of irreversible vision loss or even loss of the eye.19
425
there may or may not be damage to the underlying retina, depending on the depth of the needle pass.56 Even if a retinal hole or tear does occur, the management is controversial because the risk of a subsequent retinal detachment is still quite low. In a survey of 223 surgeons by Simon et al., there were only 14 retinal detachments reported from 728 recognized scleral perforations (1.9%).63 Given that the study included an estimated 554,000 strabismus procedures in total, the incidence of retinal detachment was 1 in 39,600 cases overall. In younger patients with formed vitreous, a retinal detachment is extremely unlikely and animal model studies have suggested that treatment is not superior to observation.64 In older patients or in cases with extensive retinal damage, prophylactic treatment with laser retinopexy is likely warranted.65
ENDOPHTHALMITIS Although exceedingly rare, postoperative endophthalmitis is often catastrophic when it does occur. Survey data have suggested that the incidence of endophthalmitis after strabismus surgery is in the range of 1 in 30,000 to 185,000 cases.42,63 Even with recognized scleral perforation, endophthalmitis is still very uncommon, occurring in only 0.4% of known perforations.63 There is an ongoing debate about whether scleral perforation is a necessary prerequisite for endophthalmitis to develop, as there have been 11 reported cases with no known scleral perforation.66–70 Pathological examination of enucleated specimens was conducted in four of the 11 cases; two showed microscopic evidence of iatrogenic scleral perforation while the other two did not.66,67 Other postulated mechanisms for postoperative endophthalmitis include endogenous seeding and intraocular progression from a localized abscess of the sclera.67,71 While there is no conclusive evidence for either of these alternative mechanisms, in two of the six cases reported by Recchia et al., the affected patients were diagnosed with sepsis prior to being diagnosed with endophthalmitis, suggesting the possibility of intraocular seeding from a systemic source.67 The outcome of endophthalmitis is very poor overall, and most affected eyes become blind and phthisical, often requiring enucleation.66,67 Despite the dismal prognosis, early recognition and aggressive treatment is still crucial as there have been several reported cases with good visual outcomes.68,70,72
ANTERIOR SEGMENT ISCHEMIA RETINAL DETACHMENT While an iatrogenic scleral perforation typically causes damage to the immediately adjacent choroid, !
2014 Informa Healthcare USA, Inc.
Anterior segment ischemia is an uncommon but wellestablished complication of strabismus surgery. A survey of the members of AAPOS revealed 30 cases of
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
426 M. J. Wan and D. G. Hunter anterior segment ischemia from an estimated total of 400,000 strabismus procedures (1 in 13,300 cases).73 However, this is likely a significant underestimate because many mild cases resolve spontaneously.74 The risk of anterior segment ischemia is influenced by both patient susceptibility and the extent of the strabismus surgery. The most important patient risk factor is older age;75 other reported risk factors include atherosclerosis, blood dyscrasias, hyperviscosity syndromes, carotid artery ligation, and Graves ophthalmopathy.76–78 Prior eye muscle surgeries and the extent of the strabismus surgery also play a significant role, as the vast majority of reported cases involve operating on three or four rectus muscles, simultaneously or staged, in the same eye.79 Microvascular dissection with preservation of the anterior ciliary vessels during strabismus surgery may help to prevent anterior segment ischemia, but does not eliminate the risk entirely.80 Muscle plication, as an alternative to resection, has also been utilized in an effort to preserve ciliary vasculature.81 In patients at high risk of anterior segment ischemia, preoperative anterior segment fluorescein angiography may be useful to assess the state of the anterior circulation and better define the risk prior to undergoing strabismus surgery.82–84
DISCUSSION Like all surgical procedures, strabismus surgery carries a number of risks and potential complications. Common complications, such as conjunctival injection, scarring, dellen, cysts, and pyogenic granulomas, usually resolve with conservative management and time. Serious complications, such as slipped muscles, lost muscles, stretched scars, incarcerated muscles, pulled-in-two syndrome, scleral perforations, retinal detachments, endophthalmitis, periocular infections, and anterior segment ischemia, are uncommon, but often need more definitive intervention and carry a significant risk of permanent sequelae. Finally, strabismus surgery has a number of distinctive features that can predispose surgeons to making surgical errors. It is critical for strabismus surgeons, and all members of the surgical team, to remain constantly vigilant about the risk of errors and to adhere to the systems designed to prevent such errors from occurring. While strabismus surgeons can take precautions to minimize the probability of surgical errors and complications, the risks cannot be eliminated entirely, and it is important for both strabismus surgeons and patients to be aware of the risks when planning, performing, and recovering from surgery.
SURGICAL ERRORS There are features specific to strabismus surgery that may increase the risk of surgical errors.85 For instance, strabismus surgery is often performed on multiple muscles in one or both eyes and several terms are easily confused, such as esotropia/exotropia, hypertropia/hypotropia, adduction/abduction, and recession/resection. Based on a systematic review, the surgical error rate for all surgical specialties was estimated to be between 0.09 to 4.5 errors per 10,000 cases.86 For strabismus surgery, a survey of 517 strabismus surgeons found that 33.5% of the respondents had made a surgical error at some point during their career with an overall incidence of 1 in 2506 cases (4.0 errors per 10,000 cases).85 Errors included operating on the wrong eye, wrong patient, or wrong muscle (e.g., inferior rectus muscle instead of inferior oblique or medial rectus muscle), or performing the wrong procedure.85 The risk was higher with inexperienced surgeons, confusion about the underlying deviation or surgical plan, ocular torsion, operating in more than one room on the same day, or failing to mark the eye in unilateral cases. Based on the findings of the study, the authors recommended several preoperative steps to reduce the risk of surgical errors, including preoperative verification of ocular misalignment, site marking, and performing a preoperative ‘‘time out’’ that includes the deviation, specific muscles to be operated on, and the intended procedure.
DECLARATION OF INTEREST The first author, Michael Wan, has no financial disclosures or conflicts. The senior author, Dr. David G Hunter, has the following financial disclosures: (1) Boston Children’s Hospital: Patent; (2) Johns Hopkins University: Patent; (3) Lippincott Williams Wilkins: Book royalties; (4) Slack, Inc: Book royalties; (5) REBIScan, Inc: Consultant, equity owner. None of these are referred to in the manuscript or apply directly to the content.
REFERENCES 1. Remy C, Aracil P. History of strabismus surgery. J Fr Ophtalmol 1984;7(6–7):493–498. 2. Helveston EM. Surgical Management of Strabismus: A Practical and Updated Approach, 5th ed. Oostende, Belgium: Wayenborgh Publishing, 2005. 3. Approved by the Board of Trustees, American Academy of Ophthalmology. Practice guidelines for informed consent. The American Academy of Ophthalmology 2011:1–6. 4. Escardo´-Paton JA, Harrad RA. Duration of conjunctival redness following adult strabismus surgery. J AAPOS 2009; 13(6):583–586. 5. Scharwey K, Gra¨f M, Becker R, Kaufmann H. Healing process and complications after eye muscle surgery. Ophthalmologe 2000;97(1):22–26. 6. Leoson Y, Øgard C, Mortzos P. Conjunctival autograft as treatment for anterior displacement and scarring of the plica Seminars in Ophthalmology
Complications of Stabismus Surgery
7. 8. 9.
10.
11.
12.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
13.
14.
15.
16.
17.
18. 19. 20.
21. 22. 23.
24. 25.
26.
27.
28.
29.
!
semilunaris after strabismus surgery. J AAPOS 2013; 17(5):528–529. Fresina M, Campos EC. Corneal ‘‘dellen’’ as a complication of strabismus surgery. Eye (Lond) 2009;23(1):161–163. Perez I. The ‘‘scleral dellen,’’ a complication of adjustable strabismus surgery. J AAPOS 2002;6(5):2–2. Lee DH, Herion MA, Unwin DR, Cruz OA. Scleral dellen after bilateral adjustable suture medial rectus muscle resection. J AAPOS 2003;7(3):221–222. Guadilla AM, de Lian˜o PG, Merino P, Franco G. Conjunctival cysts as a complication after strabismus surgery. J Pediatr Ophthalmol Strabismus 2011;48(5):298–300. Khan AO, Al-Katan H, Al-Baharna I, Al-Wadani F. Infected epithelial inclusion cyst mimicking subconjunctival abscess after strabismus surgery. J AAPOS 2007;11(3):303–304. Kushner BJ. Subconjunctival cysts as a complication of strabismus surgery. Arch Ophthalmol 1992;110(9):1243–1245. Curtis TH, Stout AU, Drack AV, Durairaj VD. Giant orbital cysts after strabismus surgery. Am J Ophthalmol 2006; 142(4):697–699. Song JJ, Finger PT, Kurli M, Wisnicki HJ, Iacob CE. Giant secondary conjunctival inclusion cysts: A late complication of strabismus surgery. Ophthalmology 2006; 113(6):1045–1052. Ullrich CR, Garola RE, Cibis GW. Bilateral extraocular muscle epithelial inclusion cysts as a complication of strabismus surgery. J AAPOS 2003;7(5):366–367. Lally DR, Eagle RC, Wasserman BN. Occult intraorbital conjunctival inclusion cyst discovered almost 70 years after strabismus surgery. J Pediatr Ophthalmol Strabismus 2013;50 Online:e15–7. Espinoza GM, Lueder GT. Conjunctival pyogenic granulomas after strabismus surgery. Ophthalmology 2005; 112(7):1283–1286. Lenart TD, Lambert SR. Slipped and lost extraocular muscles. Ophthalmol Clin North Am 2001;14(3):433–442. Bradbury JA, Taylor RH. Severe complications of strabismus surgery. J AAPOS 2013;17(1):59–63. Plager DA, Parks MM. Recognition and repair of the ‘‘lost’’ rectus muscle: A report of 25 cases. Ophthalmology 1990; 97(1):131–136; discussion 136–7. Ludwig IH, Chow AY. Scar remodeling after strabismus surgery. J AAPOS 2000;4(6):326–333. Ludwig IH. Scar remodeling after strabismus surgery. Trans Am Ophthalmol Soc 1999;97:583–651. Helveston EM, Alcorn DM, Ellis FD. Inferior oblique inclusion after lateral rectus surgery. Graefes Arch Clin Exp Ophthalmol 1988;226(2):102–105. Kushner BJ. Superior oblique tendon incarceration syndrome. Arch Ophthalmol 2007;125(8):1070–1076. Aguirre-Aquino BI, Riemann CD, Lewis H, Traboulsi EI. Anterior transposition of the inferior oblique muscle as the initial treatment of a snapped inferior rectus muscle. J AAPOS 2001;5(1):52–54. Erzurum SA, Greenwald MJ. The Pulled-in-Two Syndrome: A survey of AAPO&S Members. Proceedings of the 1991 Meeting of the American Association of Pediatric Ophthalmology and Strabismus. Montreal, Canada, May 15–19, 1991. Wallace DK, Virata SR, Mukherji SK. Strabismus surgery complicated by ‘‘pulled in two syndrome’’ in a case of breast carcinoma metastatic to the medial rectus muscle. J AAPOS 2000;4(2):117–119. Dunbar JA, Lueder GT. Intraoperative dehiscence of a rectus muscle: Report of two cases. J AAPOS 1997; 1(3):175–177. MacEwen CJ, Lee JP, Fells P. Aetiology and management of the ‘‘detached’’ rectus muscle. Br J Ophthalmol 1992; 76(3):131–136.
2014 Informa Healthcare USA, Inc.
427
30. Kowal LL, Wutthiphan SS, McKelvie PP. The snapped inferior rectus. Aust N Z J Ophthalmol 1998; 26(1):29–35. 31. Akbari MR, Jafari AK, Ameri A, Anvari F, Eshraghi B, Masoomian B. Successful extraocular muscle re-resection for a strabismus surgery complication: A ‘‘snapped’’ [severed, inadvertently] and retrieved inferior rectus muscle: A case report. Binocul Vis Strabolog Q Simms Romano 2012;27(1):41–45. 32. Callahan MA. Surgically mismanaged ptosis associated with double elevator palsy. Arch Ophthalmol 1981; 99(1):108–112. 33. Pacheco EM, Guyton DL, Repka MX. Changes in eyelid position accompanying vertical rectus muscle surgery and prevention of lower lid retraction with adjustable surgery. J Pediatr Ophthalmol Strabismus 1992; 29(5):265–272. 34. Gokyigit B, Akar S, Yilmaz OF. A novel technique for inferior rectus recession. Clin Ophthalmol 2014;8:263–269. 35. Akbari MR, Raygan F, Ameri A, et al. Lower eyelid retractor lysis versus Lockwood advancement to minimize lower eyelid retraction resulting from inferior rectus muscle recession. J AAPOS 2013;17(4):445–447. 36. Liao SL, Shih MJ, Lin LL-K. A procedure to minimize lower lid retraction during large inferior rectus recession in Graves ophthalmopathy. Am J Ophthalmol 2006; 141(2):340–345. 37. Kushner BJ. Intractable diplopia after strabismus surgery in adults. Arch Ophthalmol 2002;120(11):1498–1504. 38. Pratt-Johnson JA, Tillson G. Suppression in strabismus: An update. Br J Ophthalmol 1984;68(3):174–178. 39. Simon JW, Paskowski JR. Intractable diplopia after overcorrection of vertical strabismus. Am J Ophthalmol 1994; 117(5):675–676. 40. Santiago AP, Rosenbaum AL. Grave complications after superior oblique tenotomy or tenectomy for Brown syndrome. J AAPOS 1997;1(1):8–15. 41. Castleberry C, Arnoldi K. Predicting postoperative paradoxical diplopia. Am Orthopt J 2003;53:88–97. 42. Ing MR. Infection following strabismus surgery. Ophthalmic Surg 1991;22(1):41–43. 43. Kivlin JD, Wilson ME. Periocular infection after strabismus surgery: The Periocular Infection Study Group. J Pediatr Ophthalmol Strabismus 1995;32(1):42–49. 44. Lau FHS, Leung TF, Fan DSP. An unusual complication after strabismus surgery. Hong Kong Med J 2009;15(4): 297–298. 45. Armesto A, Ugrin MC. Orbital cellulitis after faden operation on the medial rectus. Strabismus 2007;15(4): 215–219. 46. Basheikh A, Superstein R. A child with bilateral orbital cellulitis one day after strabismus surgery. J AAPOS 2009; 13(5):488–490. 47. Hoyama E, Limawararut V, Leibovitch I, et al. Blinding orbital cellulitis: A complication of strabismus surgery. Ophthal Plast Reconstr Surg 2006;22(6):472–473. 48. Wilson ME. Topical antibiotic/steroid medication for infection prophylaxis after strabismus surgery: Is it custom or science? J AAPOS 2008;12(4):321–321. 49. Wortham E, Anandakrishnan I, Kraft SP, et al. Are antibiotic-steroid drops necessary following strabismus surgery? A prospective, randomized, masked trial. J Pediatr Ophthalmol Strabismus 1990;27(4):205–207. 50. Koederitz NM, Neely DE, Plager DA, et al. Postoperative povidone-iodine prophylaxis in strabismus surgery. J AAPOS 2008;12(4):396–400. 51. Gottlieb F, Castro JL. Perforation of the globe during strabismus surgery. Arch Ophthalmol 1970;84(2): 151–157.
Semin Ophthalmol Downloaded from informahealthcare.com by Michigan University on 02/25/15 For personal use only.
428 M. J. Wan and D. G. Hunter 52. Kaluzny J, Ralcewicz H, Perlikiewicz-Kikielowa A. Eye fundus periphery after operation for squint (author’s transl). Klin Oczna 1977;47(12):557–558. 53. Morris RJ, Rosen PH, Fells P. Incidence of inadvertent globe perforation during strabismus surgery. Br J Ophthalmol 1990;74(8):490–493. 54. Cibis GW. Incidence of inadvertent perforation in strabismus surgery. Ophthalmic Surg 1992;23(5):360–361. 55. Berger RW, Haase W. Original papers: Complications in strabismus surgery. Strabismus 1997;5(2):67–72. 56. Noel LP, Bloom JN, Clarke WN, Bawazeer A. Retinal perforation in strabismus surgery. J Pediatr Ophthalmol Strabismus 1997;34(2):115–117. 57. Surachatkumtonekul T, Phamonvaechavan P, Kumpanardsanyakorn S, et al. Scleral penetrations and perforations in strabismus surgery: Incidence, risk factors and sequelae. J Med Assoc Thai 2009;92(11):1463–1469. 58. Taherian K, Sharma P, Prakash P, Azad R. Scleral perforations in strabismus surgery: Incidence and role of prophylactic cryotherapy: A clinical and experimental study. Strabismus 2004;12(1):17–25. 59. Park K, Hong S, Chung W, et al. Inadvertent scleral perforation after strabismus surgery: Incidence and association with refractive error. Can J Ophthalmol 2008; 43(6):669–672. 60. Awad AH, Mullaney PB, Al-Hazmi A, et al. Recognized globe perforation during strabismus surgery: Incidence, risk factors, and sequelae. J AAPOS 2000;4(3):150–153. 61. Dang Y, Racu C, Isenberg SJ. Scleral penetrations and perforations in strabismus surgery and associated risk factors. J AAPOS 2004;8(4):325–331. 62. Haugen OH, Kjeka O. Localized, extreme scleral thinning causing globe rupture during strabismus surgery. J AAPOS 2005;9(6):595–596. 63. Simon JW, Lininger LL, Scheraga JL. Recognized scleral perforation during eye muscle surgery: Incidence and sequelae. J Pediatr Ophthalmol Strabismus 1992; 29(5):273–275. 64. Bagheri A, Erfanian-Salim R, Ahmadieh H, et al. Globe perforation during strabismus surgery in an animal model: Treatment versus observation. J AAPOS 2011;15(2):144–147. 65. Sprunger DT, Klapper SR, Bonnin JM, Minturn JT. Management of experimental globe perforation during strabismus surgery. J Pediatr Ophthalmol Strabismus 1996; 33(3):140–143. 66. Huang S, Crawford JB, Rutar T. Pathological findings in poststrabismus surgery endophthalmitis. J AAPOS 2011; 15(1):98–100. 67. Recchia FM, Baumal CR, Sivalingam A, et al. Endophthalmitis after pediatric strabismus surgery. Arch Ophthalmol 2000;118(7):939–944. 68. Lenahan DS, Kutschke PJ, Scott WE. Endophthalmitis following pediatric strabismus surgery with good visual result. Am Orthopt J 2004;54:152–154.
69. Thomas JW, Hamill MB, Lambert HM. Streptococcus pneumoniae endophthalmitis following strabismus surgery. Arch Ophthalmol 1993;111(9):1170–1171. 70. Kushner BJ, Meyers FL. Good visual outcome after endophthalmitis in an eye previously treated successfully for amblyopia. J Pediatr Ophthalmol Strabismus 1989; 26(2):69–71. 71. Rosenbaum AL. Endophthalmitis after strabismus surgery. Arch Ophthalmol 2000;118(7):982–983. 72. Walton RC, Cohen AS. Staphylococcus epidermidisendophthalmitis following strabismus surgery. J AAPOS 2004;8(6):592–593. 73. France TD, Simon JW. Anterior segment ischemia syndrome following muscle surgery: The AAPO&S experience. J Pediatr Ophthalmol Strabismus 1986;23(2):87–91. 74. Saunders RA, Sandall GS. Anterior segment ischemia syndrome following rectus muscle transposition. Am J Ophthalmol 1982;93(1):34–38. 75. Bleik JH, Cherfan GM. Anterior segment ischemia after the Jensen procedure in a 10-year-old patient. Am J Ophthalmol 1995;119(4):524–525. 76. Saunders RA, Bluestein EC, Wilson ME, Berland JE. Anterior segment ischemia after strabismus surgery. Surv Ophthalmol 1994;38(5):456–466. 77. Jacobs DS, Vastine DW, Urist MJ. Anterior segment ischemia and sector iris atrophy: After strabismus surgery in a patient with chronic lymphocytic leukemia. Ophthalmic Surg 1976;7(4):42–48. 78. Wolf E, Wagner RS, Zarbin MA. Anterior segment ischemia and retinal detachment after vertical rectus muscle surgery. Eur J Ophthalmol 2000;10(1):82–87. 79. Saunders RA, Phillips MS. Anterior segment ischemia after three rectus muscle surgery. Ophthalmology 1988; 95(4):533–537. 80. Murdock TJ, Mills MD. Anterior segment ischemia after strabismus surgery with microvascular dissection. J AAPOS 2000;4(1):56–57. 81. Velez FG, Demer JL, Pihlblad MS, Pineles SL. Rectus muscle plication using an adjustable suture technique. J AAPOS 2013;17(5):480–483. 82. Kaeser P-F, Klainguti G. Anterior segment angiography in strabismus surgery. Klin Monbl Augenheilkd 2012; 229(4):362–364. 83. Hayreh SS, Scott WE. Fluorescein iris angiography. I. Normal pattern. Arch Ophthalmol 1978; 96(8):1383–1389. 84. Hayreh SS, Scott WE. Fluorescein iris angiography. II. Disturbances in iris circulation following strabismus operation on the various recti. Arch Ophthalmol 1978; 96(8):1390–1400. 85. Shen E, Porco T, Rutar T. Errors in strabismus surgery. JAMA Ophthalmol 2013;131(1):75–79. 86. Devine J, Chutkan N, Norvell DC, Dettori JR. Avoiding wrong site surgery: A systematic review. Spine 2010;35(Suppl 9):S28–S36.
Seminars in Ophthalmology
