Conjunctival Incisions for Strabismus Surgery: A Comparison of Techniques

Transcription

1 Techniques in Ophthalmology 5(3): , 2007 P E D I A T R I C S U R G E R Y Conjunctival Incisions for Strabismus Surgery: A Comparison of Techniques David A. Sami, MD Pediatric Subspecialty Faculty Division Chief Pediatric Ophthalmology and Strabismus Children s Hospital of Orange County Orange County, CA Ó 2007 Lippincott Williams & Wilkins, Philadelphia PERSPECTIVE A number of articles have been published on the technical details of different strabismus incisions. In general, there are 3 basic approaches: limbal, 1,2 paralimbal, 3,4 and fornix 5,6 incisions, and there are variations on each type. The rationale for selecting a specific conjunctival incision for a particular strabismus operation is generally neglected in the ophthalmic literature. Also, there is not a review that has organized or catalogued the various modifications described in the past 2 decades. The initial conjunctival incision is a crucial part of strabismus surgery, as it facilitates the subsequent steps of exposure, muscle manipulation, and closure. Different surgeons may use different incisions for the same surgery, which for the novice surgeon may be confusing. The purpose of this article is not to dictate one specific technique, but rather to discuss the relative advantages and disadvantages of each approach. APPROACH There are 3 basic approaches to strabismus surgery: 1. limbal incision, 2. paralimbal incision 3. fornix (or cul-de-sac) incision. Limbal Incision The limbal incision (Fig. 1A) permits direct access to the subytenon spacevbecause Tenon capsule and conjunctiva are fused into one layer close to the limbus (about 2 mm). 7 It is best to start by making an initial radial incision, 2 to permit placement of the posterior blade of the scissors about 3 mm from the limbus (Fig. 1B). The blade is then moved anteriorly toward the limbus, to perform a peritomy and to gain access to the subytenon space. Address correspondence and reprint requests to David A. Sami, MD, 845 West LaVeta Suite 107B, Orange, CA ( DSami@CHOC.ORG). The advantages of limbal incisions are most relevant to the following: 1. reoperations in which previous scarring has disrupted the normal anatomic planes that separate Tenon capsule and conjunctiva because Tenon and conjunctiva are fused near the limbus (;2 mm) 7 ; 2. operations in which conjunctival cicatricial changes are associated with restrictive strabismusvmaking conjunctival recession a consideration 8 3. surgery in the very elderly, in which the conjunctiva has lost much of its normal elasticity. The disadvantages of limbal incisions include 1. increased risk for irritation from conjunctival sutures placed for closure as compared with the fornix incision; 2. higher risk of noticeable conjunctival scarring, that is, cicatricial changes within the palpebral fissure; 3. potential complications from corneal dellen formation 9 ; 4. possible loss of stem cells at the limbus interference with possible future trabeculectomy (from conjunctival scarring) when the peritomy is placed superiorly. A number of simplified limbal approaches have been described and are outlined as follows: 1. Triangular limbal flap 11 (Fig. 2). In the author s description, the advantage of this approach is that the conjunctival closure may be achieved with a single limbal suture. 2. Radial incision for horizontal rectus muscle surgery. 12 (Figs. 3A and B). The incision is placed radially, passing above the superior border of the rectus muscle insertion. The incision has to be stretched to expose the muscle insertion, which carries a risk of inadvertent conjunctival tearing. 3. Large inferior limbal peritomy (from 2Y10 o clock) to access the horizontal recti 13 (Fig. 4). In the author s Volume 5, Issue 3 125

2 Sami FIGURE 1. A and B, Limbal approach. 2 A, The limbal incision (outlined in red). B, Approach: an initial radial incision is made to permit placement of the posterior blade of the scissors between the sclera and Tenon layer about 3 mm from the limbus. The blade is then moved anteriorly toward the limbus, to perform a peritomy. FIGURE 3. A and B, Radial incision. 12 The incision is outlined in red. A, On the limbal side, the incision is made just above the normal position of the superior eyelid margin to reduce discomfort from sutures. B, Demonstration of muscle exposure. The incision is stretched with a small muscle hook to expose the muscle insertion. description, no limbal stay-suture is used, and the conjunctival incision is left unsutured. 13 Both recti are approached through a single incision, as opposed to making 2 separate limbal incisions to expose the medial and lateral rectus muscles. 1,14 4. One-snip, horseshoe-shaped limbal incision 15 (Figs. 5A and B). The Paralimbal Incision 1. The Swan method places the conjunctival incision behind the muscle insertion and parallel to the limbus. The conjunctiva is then dissected anteriorly, and the Tenon capsule is opened just anterior to the muscle insertion and perpendicular to the conjunctival incision (Fig. 6). Tenon capsule and conjunctiva are closed in separate layers. 4 Tenon capsule is first incised anterior to the muscle insertion to avoid injury to the ciliary vessels. The main advantages of this approach are direct access to and good exposure of the muscle insertion. The major disadvantage is the risk of inadvertent injury to the muscle belly and the ciliary vessels at the muscle insertion, with hematoma formation and brisk bleeding, respectively. 2. Alternatively, a paralimbal incision may be made halfway between the muscle insertion and the limbus 3 (Fig. 7). The advantage is to minimize the potential risk of injury to the muscle and associated bleeding, when making the conjunctival incision. Still, care must be taken to not injure the muscle belly when dissecting posteriorly toward the muscle insertion. The disadvantages of the relatively anterior conjunctival incision are similar to the limbal incision: postoperative irritation from conjunctival sutures in the palpebral fissure and increased risk of noticeable postoperative scarring. 4 Fornix Incision The fornix incision is one of the more popular and versatile incisions for strabismus surgery; it has many advantages and a few disadvantages. The conjunctival FIGURE 2. Triangular limbal flap. 11 The incision is outlined in red. The incision is placed above the normal position of the superior eyelid margin, to reduce discomfort from sutures. FIGURE 4. Large inferior limbal peritomy. 13 The incision is outlined in red. Both horizontal recti may be approached through a single incision, as opposed to making 2 separate limbal incisions to expose the medial and lateral rectus muscles. 1, Techniques in Ophthalmology

3 Conjunctival Incisions for Strabismus Surgery FIGURE 5. A and B, One-snip, horseshoe-shaped incision.15 A, Demonstration of approachvthe stretch lines in blue represent the tenting of conjunctiva by forceps. The conjunctiva and Tenon capsule are grasped together with a toothed forceps about 3 mm from the limbus. Westcott scissors is used to make a 1-snip incision through the conjunctiva and Tenon layer. B, The resultant exposure is outlined in red. incision is made on the bulbar side of the cul-de-sac. Placing an incision in the cul-de-sac or on the palpebral side is associated with profuse bleeding.5 In general, an inferotemporal incision is placed for the lateral rectus, and an inferomedial incision is used for the medial rectus. If supraplacement of the muscle insertion is being considered for correction of an A or V pattern, it is best to use a superior fornix incision.5 The eye is grasped at the limbus with a tooth forceps and is gently rotated clockwise and counterclockwise; this will facilitate visualization of the ciliary vessels at each muscle insertion. The incision should be placed near the fornix at a point midway between the muscle insertions. This will prevent accidental injury to the muscle belly when making the incision and also ensures conjunctival coverage over the operated muscle after surgery. FIGURE 6. The Swan incision.4 The conjunctival incision is made posterior to the muscle insertion (outlined in red). The Tenon capsule incision is made perpendicular to the conjunctival incision (outlined in blue). The Tenon capsule incision is started anterior to the muscle insertion, to decrease the risk of injury to the ciliary vessels and associated bleeding.4 FIGURE 7. The paralimbal incision.3 The incision is outlined in red. Note that the incision is halfway between the muscle insertion and the limbus. The advantages of the fornix incision are the following: 1. Unlikely to cause noticeable scarring because the incision is tucked in the fornix.5 FIGURE 8. Fornix incision.5 The conjunctival incision may be made parallel to the fornix (A and B) or perpendicular to the fornix (C and D). The conjunctival wound is outlined in red (A and C). The blue arrows demonstrate the path of possible tearing from overstretching of the conjunctiva to expose the muscle insertion (B and D). A and B, When the incision is placed perpendicular to the fornix/parallel to the muscle belly, less stretch is necessary to reflect the conjunctiva over the muscle insertion. C and D, When the incision is placed parallel to the fornix, a larger incision must be made to accommodate greater stretching required to expose the muscle insertion. Volume 5, Issue 3 127

4 Sami FIGURE 9. Modified fornix incision for reoperation procedures. 21 The incision in outlined in red. After an initial perpendicular fornix incision (Fig. 8A), the conjunctiva is tented up over the muscle, and a second conjunctival incision is made parallel to the muscle belly on the other side. The incisions are joined over the muscle belly to expose the muscle. 2. A single incision potentially allows access to more than 1 muscle. 6 For example, an inferotemporal incision allows access to the lateral and inferior recti; a superotemporal incision permits access to the superior and lateral recti. 3. Reoperations may be performed again through the original fornix incision scar Minimal discomfort from sutures placed at the site of conjunctival closure. The fornix incision is also popular in adjustable strabismus surgery because it provides coverage of the muscle without the need for conjunctival closure, 6 permitting delayed suture adjustment. Limbal incisions may also be used with the adjustable suture technique. 16Y19 The major disadvantage of the fornix incision is that it requires a certain amount of elasticity in the conjunctiva to permit reflection of the conjunctiva over the insertion of the muscle. Thus, in the elderly patients, there is a higher risk of conjunctival tearing. The orientation of the incision is important in this regard, that is, parallel to the fornix 5 or perpendicular to it (Figs. 8AYD). When the incision is placed perpendicular to the fornix, the incision is closer/parallel to the muscle belly, requiring less stretch to reflect the conjunctiva over the muscle insertion. However, if the incision tears, it can tear toward the limbus, creating a potentially uncomfortable suture line (Fig. 8B). An incision parallel to the fornix, although more distant from the muscle insertion, is more likely to extend or tear in a line parallel to the fornix. It is also possible for the parallel incision to extend into the palpebral fissure (Fig. 8D). Thus, some surgeons prefer to use a perpendicular fornix suture in children (Fig. 8A), in whom the conjunctiva is more elastic, and a larger parallel fornix incision in the elderly (Fig. 8C). The parallel fornix incision is also best for inferior oblique surgery. 20 When a fornix incision is considered for adjustable suture technique, a perpendicular incision is probably more appropriate as it permits easier access to the muscle insertion for postoperative suture adjustment. A reported approach for preventing inadvertent conjunctival tearing from overstretching in reoperation procedures is to use a standard perpendicular fornix incision, and with the conjunctiva tented up with muscle hook, to make a second conjunctival incision parallel to the muscle belly on the other side. The conjunctival incisions are joined over the muscle belly to expose the muscle and its insertion 21 (Fig. 9). The disadvantage of this technique is having to close a large conjunctival wound. CONCLUDING THOUGHTS Ultimately, the choice of which technique to usev limbal, paralimbal, or fornixvis up to the surgeon. There has not been any large-scale study on the complication rates, outcomes, and patient satisfaction with different types of conjunctival incisions. 15 In the correct hands, all the approaches are likely efficacious and yield good results. It is to be hoped that this comparison of the basic techniques and review of the various modifications will help the novice strabismus surgeon to become more empowered in developing his or her own approach. REFERENCES 1. Von Noorden GK. The limbal approach to surgery of the rectus muscles. Arch Ophthalmol. 1968;80:94Y Von Noorden GK. Modification of the limbal approach to surgery of the rectus muscles. Arch Ophthalmol. 1969;82: 349Y Santiago AP, Isenberg SJ, Neumann D, et al. The paralimbal approach with deferred conjunctival closure for adjustable strabismus surgery. Ophthalmic Surg Lasers. 1998;29:151Y Swan KC, Talbot T. Recession under Tenon s capsule. AMA Arch Ophthalmol. 1954;51:32Y Parks MM. Fornix incision for horizontal rectus muscle surgery. Am J Ophthalmol. 1968;65:907Y Nelson LB, Calhoun JH, Harley RD, et al. Cul-de-sac approach to adjustable strabismus surgery. Arch Ophthalmol. 1982;100:1305Y Calhoun JH, Nelson LB, Harley RD. Atlas of Pediatric Ophthalmic Surgery. Philadelphia, PA: Saunders, 1987:23Y Techniques in Ophthalmology

5 Conjunctival Incisions for Strabismus Surgery 8. Cole JG, Cole HG. Recession of the conjunctiva in complicated eye muscle operations. Am J Ophthalmol. 1962; 53:618Y Tessler HH, Urist MJ. Corneal dellen in the limbal approach to rectus muscle surgery. Br J Ophthalmol. 1975; 59:377Y Holland EJ, Schwartz GS. Iatrogenic limbal stem cell deficiency. Trans Am Ophthalmol Soc. 1997;95:95Y Fells P. Simplified limbal approach in squint surgery. Br J Ophthalmol. 1971;55:550Y Velez G. Radial incision for surgery of the horizontal rectus muscles. J Pediatr Ophthalmol Strabismus. 1980;17:106Y Callear AB, Eagling EM. A novel conjunctival incision for horizontal strabismus surgery. Eye. 1995;9(pt 3): 282Y Willshaw HE. Rectus muscle surgeryvhow to do it. Trans Ophthalmol Soc U K. 1986;105(pt 5):583Y Caputo AR, Guo S, DeRespinis P, et al. Simplified limbal incision for extraocular rectus muscle surgery. Ophthalmic Surg. 1991;22:406Y Rosenbaum AL. The use of adjustable suture procedures in strabismus surgery. Am Orthopt J. 1978;28:88Y Kraft SP, Jacobson ME. Techniques of adjustable suture strabismus surgery. Ophthalmic Surg. 1990;21:633Y Schwartz RL, Choy AE, Cooper CA. Delayed conjunctival closure in adjustable strabismus surgery. Ophthalmology. 1984;91:954Y Eustis HS, Ellis GS Jr. Delayed conjunctival closure in adjustable sutures. South Med J. 1987;80:738Y Chandna A, Yang YC. Surgical minutiae. Surgical approach to inferior oblique weakening procedures. Eye. 1996;10(pt 5):626Y MacDonald IM. A modified conjunctival incision for strabismus surgery. Can J Ophthalmol. 1997;32:175Y176. Volume 5, Issue 3 129