Introduction
Although primary vitrectomy is being increasingly utilized, an essential surgical procedure for the repair of certain rhegmatogenous retinal detachments is scleral buckling. The goal of scleral buckling is to close retinal breaks by indenting the eye wall, thus preventing the passage of liquefied vitreous into the subretinal space. This flexible approach incorporates the benefits and advantages of different techniques and materials, maximizing the rate of anatomical and visual success while minimizing potential complications.
Historical Review
Recognition of vitreoretinal traction and retinal breaks in the pathogenesis of retinal detachment by Gonin in 1919 ushered in the era of repair, in which drainage of subretinal fluid and treatment of retinal breaks were employed. Custodis, 30 years later, introduced the concept of scleral buckling. The introduction of the binocular indirect ophthalmoscope and scleral depression by Schepens in 1951 revolutionized the localization of peripheral retinal pathology. Advancements were made when Schepens combined scleral dissection, diathermy, and intrascleral implantation of silicone buckles for scleral buckling. Lincoff et al. refined Custodis’ procedure by using silicone sponge explants and cryotherapy.
Preoperative Evaluation and Diagnostic Approach
The diagnosis of rhegmatogenous retinal detachment is suggested by symptoms of floaters, photopsia, peripheral vision loss, and decreased central vision in cases of macular involvement. In patients with clear media, the diagnosis is confirmed by indirect ophthalmoscopy with scleral depression. Slit-lamp biomicroscopy with a three-mirror contact lens may also be helpful in identification of retinal pathology and localization of retinal breaks. The location and type of retinal breaks, as well as the size and duration of retinal detachment, are factors that help determine the timing and type of scleral buckling procedure performed.
Optical coherence tomography (OCT) is useful in documenting subretinal fluid, especially in the macula, and the extent of any accompanying intraretinal edema or epiretinal proliferation. In patients with opaque media, the retinal status may not be visualized. Diagnostic ultrasonography is critical in establishing retinal detachment.
Alternatives to Scleral Buckling
Rhegmatogenous retinal detachments can be repaired by other surgical techniques. Pneumatic retinopexy involves injection of an expansible gas bubble into the vitreous and postoperative positioning so that the gas bubble closes the retinal break. The break is treated with either cryopexy or laser photocoagulation. Pneumatic retinopexy is generally reserved for detachments in the superior hemiretina with a single break or several closely spaced breaks with clinical posterior vitreous detachment and no inferior retinal pathology.
Vitrectomy techniques, described in Chapter 6.12 , also can be used to repair rhegmatogenous retinal detachments. The indications for scleral buckling versus pneumatic retinopexy or vitrectomy remain controversial.
Anesthesia
Scleral buckling can be performed with the patient placed under local or general anesthesia. The anesthetic technique that is used is a matter of surgeon and patient preference. The advantages of local anesthesia include shorter operating time, quicker postoperative recovery, and possibly decreased morbidity and mortality. However, retrobulbar placement of local anesthetic is not without risk. Perforation of the globe, particularly in patients with myopia, and damage to the optic nerve may result in permanent visual loss. Respiratory arrest and grand mal seizures also have been reported with inadvertent intrathecal administration of retrobulbar anesthetic. These complications can be minimized with a subconjunctival or a peribulbar technique.
General Techniques
A peritomy (conjunctival opening) is performed either at the limbus or several millimeters posterior to it. Because of considerable conjunctival manipulation, radial relaxation incisions are recommended to prevent tearing. In patients who have filtering blebs or recent limbal wounds, the peritomy can be extended posteriorly to avoid those areas. If only one or two quadrants are to be buckled, conjunctiva and Tenon’s capsule can be reflected in the required quadrants only ( ).
After the peritomy, the space between Tenon’s capsule and sclera is entered, the muscle insertion is engaged with a muscle hook, and the connections to Tenon’s capsule are identified and separated from the muscle. A traction suture is placed around each of the four rectus muscles. After all recti have been isolated, the surface of the sclera is inspected for evidence of thinning (most common superotemporally), staphyloma, and anomalous vortex veins. Traction on the extraocular muscle insertions may produce a bardycardic oculocardiac reflex, so it is important to carefully monitor patient’s heart rate during this step.
No aspect of scleral buckling is more critical than accurate placement of the buckle, requiring precise localization of retinal breaks on the scleral surface. For small flap tears or holes, a single mark on the posterior edge of the break is sufficient. Larger flap tears and nonradial tears require localization of both the anterior and posterior extents of the break ( Fig. 6.11.1 ) ( ).
Treatment of Retinal Breaks
The rationale for the treatment of retinal breaks is to create an adhesion between the retinal pigment epithelium (RPE) and the retina. This is accomplished by inducing a thermal injury by using one of three energy sources: diathermy, cryotherapy, or laser. The morphological and cellular response of the retina and RPE to each of these energy sources is essentially similar. After 2 weeks, all three modalities show comparable effects on the retinal adhesive force.
Explant Scleral Buckling Techniques
Explant techniques allow the placement of buckling elements to support retinal pathology. Explants are made of either solid silicone rubber or silicone sponges and come in a variety of sizes and shapes. They are secured to the sclera with partial-thickness scleral sutures ( ). For most detachments, the selected element is not as important as the accurate localization and placement of it. Proper placement requires an effective suturing technique, involving the use of a spatula needle with a 5-0 nonabsorbable suture, such as polyester, nylon, or polypropylene. The suture is placed either snug with the band (buckle height achieved by circumferential tightening of the band) or 1 mm or more on each side (buckle height achieved by suture imbrication. To ensure that the most posterior edge of the break is supported, the posterior suture is placed a minimum of 2–3 mm posterior to the scleral localization mark.
Element placement can be either segmental or encircling. Segmental buckles usually are reserved for detachments with single or closely spaced retinal breaks, <1 clock hour in extent. Although segmental buckles close isolated tears effectively, they are less useful in preventing new breaks because they provide no support elsewhere. Encircling procedures are particularly indicated in patients with the following conditions:
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Multiple breaks in different quadrants.
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Aphakia.
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Pseudo-phakia.
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Myopia.
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Diffuse vitreoretinal pathology, such as extensive lattice degeneration or vitreoretinal degeneration.
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Proliferative vitreoretinopathy (PVR).
The anteroposterior position of the encircling element depends on the location of the pathology to be supported. When retinal breaks in the detached retina are associated with traction, the buckle should be positioned such that the posterior edge of the break lies on the posterior crest of the buckle. The buckling effect should extend for 30° on either side of the tear and extend anteriorly to the ora serrata. When the encircling element supports pathology in the attached retina, such as a retinal break, it should be positioned to support the most posterior aspect of the pathology. If no specific pathology is to be supported, the encircling element should support the posterior margin of the vitreous base.
The height of the encircling element (imbrication) can be obtained in two ways. For thin encircling elements, such as solid silicone bands, the explant can be shortened in relation to the circumference of the globe. The second method is via suture placement. This technique is used with wider and thicker explants and does not require the element to be shortened in relation to the ocular circumference. The farther apart the bites of the mattress suture are placed, the greater the height when the sutures are tightened ( ).
Drainage of Subretinal Fluid
Indications for drainage of subretinal fluid during scleral buckling remain controversial. Some authors believe that most cases can be managed without drainage, whereas others believe that drainage is a crucial aspect of the procedure. The rationale for drainage is twofold:
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To diminish intraocular volume, allowing elevation of the buckle without elevating intraocular pressure (IOP).
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To allow the retina to settle on the elevated buckle by removing fluid from the subretinal space.
Effective drainage places the retinal breaks in juxtaposition to the choroid overlying the buckle, thus facilitating closure.
The selection of an external drainage site is affected by several factors ( Fig. 6.11.2 ). Although the location of subretinal fluid is a primary concern, it is not necessary to drain where the amount of fluid is greatest but, rather, where there is adequate fluid to safely enter the subretinal space. Whenever possible, it is preferable to drain just above or below the horizontal meridian, either temporally or nasally (see Fig. 6.11.2 ), avoiding the major choroidal vessels and vortex veins.
Drainage in the posterior third of the bed of the buckle is preferred. This provides adequate support of the drainage site in the event of a complication, such as retinal incarceration or choroidal hemorrhage, and immediate closure when the buckle is tightened. If, because of the configuration of the detachment or the position of the buckle, it is not possible to drain in the bed of the buckle, closure of the site with a suture should be considered. Drainage outside the bed of the buckle allows the buckle to be pulled up as drainage proceeds. Entry through the choroid and into the subretinal space is performed with a needle (27–30 gauge), with the presence of fluid signifying entry into the subretinal space. As the fluid drains, it is important to maintain a relatively normal and constant IOP to prevent retinal incarceration and choroidal hemorrhage ( ).
After successful drainage and closure of the site, the buckle is positioned with the appropriate preplaced scleral sutures. Any suture that overlies a retinal break is tightened first. The encircling band, if present, is then adjusted with a silicone sleeve. As the sutures are tightened, they are secured with temporary ties, as this allows easy adjustment of buckle height and position, and the optic nerve is inspected for perfusion. Once the buckle is positioned and the band adjusted, the fundus is inspected again to determine the status of the breaks and perfusion of the optic nerve.
Nondrainage procedures can be used to reattach the retina, with success rates comparable with those of drainage procedures. The primary advantage of a nondrainage procedure is that it avoids the potential complications associated with drainage. In eyes with relatively shallow detachments, the eye may soften enough after scleral depression and cryopexy to allow placement of the buckle without IOP problems. Waiting several minutes between tightening of the scleral sutures also may soften the eye. However, nondrainage techniques often require the IOP to be lowered by additional medical or surgical means. An injection of a small volume of air or gas (0.2–0.4 cc of 100% SF6 or C3F8) is often used as an adjunct in drainage or nondrainage buckles, to promote closure of the retinal break.
Chandelier-Assisted Scleral Buckling
Chandelier-assisted scleral buckling is a relatively novel technique in which traditional scleral buckle placement and maneuvers (e.g., marking of retinal breaks, cryopexy, and external drainage) are performed under wide-angle visualization through the operating microscope. The visualization is enabled by endoillumination provided by a small-gauge fiberoptic chandelier placed near the beginning of the case. The advantage of this procedure is that it allows for identification of all retinal breaks even in the far periphery, which is very helpful to less experienced surgeons. It is also a great tool for teaching as it allows simultaneous viewing by the surgeon and vitreoretinal fellow. The chief disadvantage of the chandelier during primary scleral buckle is that it requires entry into the vitreous cavity and carries a small risk of vitreous incarceration at the sclerotomy site.
Closure
After final adjustments, the sutures are tied and the knots rotated posteriorly. Tenon’s capsule and the globe can then be irrigated with an antibiotic solution. Retrobulbar irrigation with 0.75% bupivacaine significantly decreases postoperative pain after general or local anesthesia.
Tenon’s capsule is then identified in all quadrants. A layered closure, initially closing Tenon’s capsule to the muscle insertions, ensures that the explant and the nonabsorbable sutures are covered by Tenon’s capsule and removes the tension on the conjunctival closure, minimizing the possibility of buckle erosion. During conjunctival closure, the relaxation incisions are typically closed with 6-0 plain gut suture or 7-0 vicryl. The conjunctiva is secured at the limbus with one or more sutures.
Long-term, a fibrous capsule forms overlying the scleral buckle, which maintains the scleral buckle position and indentation effect ( Figs. 6.11.3 and 6.11.4 ).
Treatment of Retinal Breaks
The rationale for the treatment of retinal breaks is to create an adhesion between the retinal pigment epithelium (RPE) and the retina. This is accomplished by inducing a thermal injury by using one of three energy sources: diathermy, cryotherapy, or laser. The morphological and cellular response of the retina and RPE to each of these energy sources is essentially similar. After 2 weeks, all three modalities show comparable effects on the retinal adhesive force.
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