Surgical Options Reviewed
Scleral buckling works through a variety of proposed mechanisms, some of which are generally agreed upon and some of which are not. Scleral buckling indirectly relieves radial vitreous traction, by supporting the retina and RPE in the area of the retinal breaks. Scleral buckling also displaces subretinal fluid away from breaks, bringing the neurosensory retina and RPE into closer proximity. Surgical success rates are generally in the range of 92-94% with a single operation. Visual outcomes are primarily dependent upon the preoperative status of the macula.
Regardless of specific technique, scleral buckling offers several advantages compared with other procedures. It is the most established procedure with the longest documented follow-up. Scleral buckling is appropriate for virtually all primary rhegmatogenous RDs (the exception would be rare cases with very posterior breaks) and remains the best approach, with or without concomitant pars plana vitrectomy, for inferior breaks. In general, postoperative positioning is supine, which is well tolerated by most patients. Scleral buckling may cause postoperative refractive changes (usually myopia, caused by axial elongation) or motility and alignment disturbances. Both of these complications are more common with cerclage than with segmental procedures. Scleral buckling necessarily results in a permanent intraorbital foreign body, with risks of infection, transconjunctival (external) extrusion, and trans-scleral (internal) erosion. Further more, many patients find scleral buckling a more uncomfortable procedure than pneumatic retinopexy or pars plana vitrectomy.
Pars plana vitrectomy may be used to treat a variety of disorders, including vitreous hemorrhage, traction RD, and retained lens fragments following cataract surgery. However, pars plana vitrectomy is also quite effective for either straightforward or complicated primar y rhegmatog enous RD, particularly in the pseudophakic setting. At the conclusion of surgery, either gas or silicone oil must be injected into the vitreous cavity to tamponade the break(s) until the retinopexy provides a permanent seal. All gases (including air) will spontaneously resorb during the postoperative period. If an expansile gas is used, patients must avoid certain situations in the postoperative period that may cause uncontrolled expansion of the gas bubble, and a severe intraocular pressure spike. These include environments with decreased atmospheric pressure (especially airplane travel) and certain inhalational anesthetic agents.
Regardless of tamponade agent, pars plana vitrectomy has three distinct advantages over scleral buckling or pneumatic retinopexy. First, pars plana vitrectomy is the only procedure that directly removes vitreous traction by lysing the vitreous strands adherent to the flap of the horseshoe tear. Scleral buckling only indirectly relieves vitreous traction, and pneumatic retinopexy does not relieve traction at all. Second, pars plana vitrectomy directly removes vitreous hemorrhage and pigment, clearing the visual axis. In cases with significant vitreous opacity, this allows for better intraoperative visualization and the potential for faster postoperative visual recovery. Third, pars plana vitrectomy is the only procedure that can reliably achieve complete, intraoperative retinal reattachment. This is attained either by internal drainage of subretinal fluid or by use of perfluorocarbon liquids to displace the subretinal fluid. In contrast, scleral buckling with subretinal fluid drainage typically achieves only partial reattachment, while scleral buckling without drainage and pneumatic retinopexy never achieves immediate reattachment. Immediate intraoperative retinal reattachment has improved the prognosis for giant retinal tears, although its importance for uncomplicated primary rhegmatogenous RD is much less significant.
Pneumatic retinopexy became a popular alternative to scleral buckling in the 1980s. As previously indicated however, pneumatic retinopexy does not truly relieve vitreous traction. It utilizes an intraocular gas bubble to temporarily tamponade the retinal break(s) until the retinopexy provides a per manent seal. The retina becomes spontaneously reattached, mainly through the actions of the RPE pump. Sealing of all retinal breaks is critical for success of this procedure. When indicated, pneumatic retinopexy offers several distinct advantages. In general, it offers a low morbidity (exceptions include occasional lens trauma and dehiscence of recent cataract wounds). Since there is no conjunctival incision, pneumatic retinopexy may be performed in the office and it is by far the least expensive technique. The main disadvantage of pneumatic retinopexy is its relatively limited indications. All currently available gases are lighter than water; therefore, the bubble will float to the highest part of the eye. Thus, the ideal candidate for pneumatic retinopexy is a rhegmatogenous RD with one break, or several closely spaced breaks in the superior clock hours. A rhegmatogenous RD with an inferior break would require extreme head-down positioning maneuvers, which are not tolerated by most patients. Further more, pneumatic retinopexy is a poor procedure for detachments with concomitant vitreous hemorrhage and/or proliferative vitreoretinopathy.
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