applying a sector occlusion on the operated eye, which will force it to look in elevation-adduction. Alternatively, a transpalpebral stay suture can be applied to Þx the eye in adduction-elevation. The latter will allow using the opposite eye normally and ensure that even during the night, the operated eye remains in this position. In contrast to a tenotomy, a consecutive superior oblique palsy is only rarely seen, as the anterior tendon part remains untouched. In cases showing no or insufÞcient postoperative improvement of BrownÕs syndrome repeat surgery will often disclose that not all Þbers of the abnormal posterior part of the tendon have been resected [15]. Recently, Saxena suggested visualizing the superior oblique tendon with trypan blue [23]. This could allow identifying and delineating the posterior, enlarged, inelastic part of the tendon more easily.

6.6 Postoperative Handling

Core points:

¥After surgery TobraDex¨ ointment (Alcon) is applied; the eye is not patched.

¥For 2 weeks TobraDex¨ suspension (Alcon) thrice daily and TobraDex¨ ointment (Alcon) in the evening are applied.

¥Strenuous physical activities are not allowed during the Þrst two postoperative days

¥A direct contact of the eye and the periocular region with non sterile ßuids is not allowed for 1 week

¥Irritating ßuids, fumes and dust should be avoided for about 4 weeks

Usually, at the end of surgery, TobraDex¨ ointment (Alcon, 1 mg dexamethasone and 3 mg tobramycin per gram of 0.5% chlorobutanol) is applied. No eye patch is used. For the Þrst 2 weeks after surgery, TobraDex¨ suspension (Alcon, 1 mg dexamethasone and 3 mg tobramycin per mL of 0.01% benzalkonium chloride) thrice daily and TobraDex¨ ointment (Alcon) in the evening are administered. In repeat surgery with excessive scarring, treatment should be prolonged until the conjunctival redness has disappeared completely. In the Þrst two postoperative days, strenuous physical activities are not allowed because of the risk of secondary hemorrhages. During the Þrst week, a direct contact of the eye and the periocular region with nonsterile ßuids is not allowed. Irritating ßuids (e.g.,

chlorate water in swimming pools) and irritating fumes and dust (e.g., heavily smoking environment) should be avoided for about four weeks.

6.7 Specific Complications of MISS

The intraoperative and postoperative complications of strabismus surgery are numerous. Fortunately, severe ones are rare. This chapter focuses on speciÞc complications related to minimally invasive strabismus surgery.

6.7.1 Intraoperative Complications

Traction suture: If the limbal traction suture is too superÞcial, it may pull out during surgery. A new traction suture should be applied slightly more posterior. This will usually remain unaffected. However, sometimes, such patients might experience an increased discomfort while moving the eyes on the Þrst postoperative day. A traction suture that is not limbal but slightly posterior, might induce a tear in inelastic conjunctiva of older patients while the keyhole openings are excessively displaced. A too deep limbal traction suture might penetrate the eye. The surgeon will notice a loss of anterior chamber depth and, sometimes, see aqueous humor leaking at the suture entrance or exit. The traction suture should be immediately removed and reapplied more posteriorly. Postoperatively, a Þltering bleb and hypotonia may develop. Probably, a prescription of a local topical carboanhydrase inhibitor will speed up the regression of the Þltering bleb. The traction suture should never touch the cornea because of the risk of corneal erosion. Traction sutures at the inferior, lateral, and superior limbus will usually not rub on the cornea. Traction sutures applied to the medial limbus will touch the cornea. Therefore, a hypomochlion has to be created (see 6.8.1). In exophthalmic eyes, it may be impossible to avoid corneal rubbing if only one traction suture is placed in the quadrant where surgery is planned. For such cases, two limbal traction sutures in the adjacent quadrants should be used, for example, for medial rectus surgery one at the inferior and another at the superior limbus. A disadvantage of such sutures is that they will expose the surgical site less well since

they allow only a restricted rotation of the eye. Keyhole openings: Bleeding should be stopped immediately as otherwise visibility of the anatomical structures through the small cut will be considerably reduced. Openings placed over the insertion should be avoided because of the high risk of injuring larger muscle vessels, which may result in an excessive subconjunctival hemorrhage with severely reduced visibility of the surgical site. Sometimes it is inevitable that the cuts have to be or joined at the limbus. The cuts need also to be enlarged if they have been placed at the wrong site, especially in patients with inelastic conjunctiva. Openings in repeat surgery or cuts lying near the fornix bear the risk of herniation of orbital fat. As soon as fat becomes visible, the surgeon should avoid further prolonging of the cut in the corresponding direction. Sometimes, cauterization will be necessary to stop bleeding and to retract the orbital fat. In such cases, closure of the conjunctival cuts at the end of surgery should be preceded by a separate adaptation of the TenonÕs capsule. In young children, the TenonÕs tissue might hinder good visualization of the operating site. However, usually, it is not advisable to resect the excessive TenonÕs tissue prolapsing through the keyhole openings because of the risk of a hemorrhage, which might be hard to control. Cuts with visible TenonÕs tissue should be closed by Þrst adapting TenonÕs tissue, followed by a conjunctival suture. Probably, this will enhance ease of repeat surgery using the same or other access techniques. Suturing through the small cuts has to be performed always under optimal conditions of visualization. If visibility is not full, the cuts have to be enlarged. In case of penetration or suspected penetration of the globe, the pupil has to be dilated to examine the retina at the end of surgery. If a retinal break is seen, cryocoagulation or laser coagulation should be performed. The necessity for a systemic antibiotic treatment after globe penetration remains unclear. The more experienced a surgeon gets with MISS, the smaller the conjunctival openings will be. However, this will increase the risk of conjunctival tears. Elderly patients with inelastic conjunctiva are particularly at highest risk. If a tear is purely conjunctival as it does not involve the underlying TenonÕs tissue, exact readaptation will not result in a visible scar and repeat surgery will not be negatively affected. Also the other tears will usually remain invisible and not hinder repeat surgery, unless the tear is over the muscle insertion. Desinsertion: The tendon at

the muscle insertion might tear longitudinally when the muscle is detached. This does not allow proper reinsertion of the muscle with only two sutures, as the tear would allow a posterior bowing of the middle part of the insertion. To avoid tearing, either the tension of the traction suture should be diminished before muscle desinsertion or, alternatively, the whole tendon should be stabilized with a forceps just distally from the insertion while it is desinserted. Care has to be taken to ensure that the muscle sutures are not cut. Usually, for recessions, it is preferable to pass the sutures through the sclera at the reinsertion site before desinsertion. This will help to pull the sutures away from the insertion and thus avoid inadvertently being cut during desinsertion. If the middle part of the muscle bows back at the reinsertion site, a central suture avoiding the long ciliary vessel should be performed through the tunnel. If a suture is inadvertedly cut during the desinsertion, the corresponding part of the tendon is pulled back through the cut, which will allow reapplying the suture. While usually oblique muscle desinsertion is not followed by a hemorrhage, mostly rectus muscles will. Therefore, it is advisable to cauterize all larger vessels starting about 2 mm behind the insertion and ending about 2 mm anterior to it. Bipolar diathermy with a coaxial tip is the best option to cauterize vessels through conjunctival keyhole openings while performing MISS. This type of cauter will minimize the risk of inadvertent cauterization of the conjunctiva next to the bleeding vessels. Another advantage of this type of cautery is the possibility of regulating the energy level, which will permit minimizing the risk for tissue burns. Always start with the minimal setting and hold the tip still for one or two seconds over the vessel before you decide that the settings are too low. In lateral and medial rectus recessions, never cauterize the vessels directly at the desinsertion site after tendon desinsertion as the sclera may retract, which might result in permanent visibility of the thinned sclera, usually a bluish line. If cosmetically disturbing, this may require scleral patching. To safely stop bleeding at the insertion after tendon detachment, cauterize the corresponding vessels 2 mm anterior to the desinsertion. Sometimes, after desinsertion, some Þbers remain attached. This will result in signiÞcant undercorrection. In oblique muscles the most posterior Þbers are at risk of being cut, in rectus muscles using the two keyhole openings, usually such Þbers lie in the middle of the tunnel. Thus, after muscle reattachment, always

search for such Þbers. They are best found after muscle reattachment as they will be stretched. Sometimes an anterior bowing of a part of the new insertion might indirectly point to remaining Þbers. In addition to that, inspection of the reinsertion site will ensure that none of the scleral sutures had loosened while being tied and will disclose posterior bowing of the middle part of the new insertion, both of which would result in an overcorrection. If during desinsertion a buttonhole occurs in the overlying conjunctiva, try to Þnd and excise the conjunctiva that has been cut. Otherwise, a serous conjunctival cyst may grow. Plication: In patients with abundant TenonÕs tissue, the inexperienced surgeon might grasp the tissue surrounding the muscle instead of the muscle itself. This can be avoided by liberating the muscle from the surrounding tissue at the site where the suture has to be placed. This needs to be done with caution, because often larger vessels will accompany the lateral borders of the muscle. The part of the muscle where the posterior plication suture will be applied is at risk of gliding through the grasping forceps, when pulled forward. For short plication distances, there is no need to pull the muscle anterior to apply the suture. However, for larger amounts of plication, this becomes necessary, to visualize the distal plication site through the keyhole cuts. The more the muscle has to be pulled forward, the higher the risk of gliding, which would result in an undercorrection. Check that the forceps still grasp the muscle Þrmly and avoid additionally grasping TenonÕs tissue. The proximal plication suture at the original insertion will sometimes require a dissection to get bare sclera. If the proximal plication suture is anchored to the TenonÕs tissue instead of the sclera, a signiÞcant undercorrection will result. Before trying to approximate the distal plication suture to the insertion site, the tension of the traction suture should be reduced. This is crucial for larger plication distances as otherwise the suture may rupture due to very high tension. If this happens, the corresponding plication suture has to be redone. When performing a plication of the lateral and superior rectus muscle, avoid grasping the tendon of the adjacent oblique muscle tendon. Anatomical abnormalities:

Keyhole surgery may be contraindicated if congenital, posttraumatic or postsurgical anatomical variations exist. For rectus muscle surgery, HarmsÕ conjunctival opening and for oblique muscles one large opening should be used. With increasing experience in MISS surgery, the surgeon will be able to handle such cases

through keyhole cuts. If surgery has been started using MISS openings and cannot be continued because of an unclear situation, enlargement of the cuts or, for rectus muscle surgery, joining at the limbus, will be necessary.

6.7.2 Postoperative Complications

Subconjunctival hemorrhage: In a few cases, normally during the Þrst postoperative night, a subconjunctival hemorrhage may occur. In MISS patients this will not increase discomfort; however, conjunctival redness will last longer. Local allergies: Allergic reactions from topical eye drops will induce an increasing conjunctival injection and yellowish conjunctival swelling, often combined with eyelid swelling. The patient will report a burning sensation when the eye drops are applied. All topical medications should be discontinued. Corneal dellen formation: Corneal dellen are rarely seen with the MISS technique. If they arise, they are small and resolve quickly. Patients with severe dry eye syndrome or ocular surface diseases might, however, still suffer from more pronounced corneal dellen. Prolapse of the Tenon’s tissue: If the TenonsÕ tissue prolapses through the small openings, it will be minimal and will normally not require any additional intervention. Foreign body granuloma: A foreign body granuloma usually occurs in the Þrst couple of weeks after surgery. It develops around a suture, swab fragment, or eyelash. The foreign body should be removed with the slit-lamp. In younger children this may not be possible. A transient increase of topical steroids can sometimes induce a regression and, therefore, prevent removal under general anesthesia.

Serous conjunctival cysts: In MISS patients serous conjunctival cysts may occur. Removal techniques do not differ from those used for cysts developing after open surgery. Postoperative hypotonia: As already mentioned, penetration into the anterior chamber while applying a traction suture may induce a Þltering bleb and hypotonia. Such patients may be disturbed by the refractive shift if a shallow anterior chamber persists. Although spontaneous regression can be expected, prescription of a local carboanhydrase inhibitor may speed-up regression. Injection