Pars plana vitrectomy (PPV) is increasingly used for primary repair of pseudophakic retinal detachment [1-22]. The development of wide-angle viewing systems and improvements in vitrectomy instrumentation have contributed to expanding the role of PPV in the management of RRD. At the end of the surgical procedure the vitreous cavity is filled with a tamponade agent (air, gas or silicone oil) to allow sufficient time for chorioretinal adhesion to develop and avoid seepage of fluid through the causative break [5, 20].
Postoperative morbidity increases when there are breaks located in an inferior position. Traditionally, inferior breaks present a surgical challenge because it is believed that intraocular gas tamponade cannot provide direct support to the inferior retina. In order to achieve an effective tamponade for retinal breaks, mandatory facedown positioning for 10 days is recommended . To solve this problem, various authors have combined PPV with scleral buckling [1, 3, 7, 8]. On the basis of results from a recent pilot study,
A critical step in retinal detachment repair is the development of the chorioretinal scar around the retinal break. The most important effect of cho-rioretinal adhesion in closing the retinal break is to induce a watertight seal that prevents seepage of vitreous fluid into the subretinal space [5, 23]. Although the mechanism producing the laser-induced bond within the first days after photocoagulation is uncertain, histologic studies have shown that a proteinaceous coagulum develops at the interface between the retina and the retinal pigment epithelium, followed by cicatricial adhesion due to proliferation and migration of glial cells into the wound site [6, 12, 24].
In clinical practice, a correlation with these histologic findings can be established postopera-tively. During the first 5 days, the laser spots are surrounded by retinal edema (Fig.10.2a). Over the following 7 days, the retinal edema disappears (Fig. 10.2b). Finally, in the second week, a chorioretinal scar develops (Fig. 10.2c). During this period the strength of the chorioretinal adhesion increases. However, experimental studies have shown that fresh laser burns produce a greater than normal adhesive bond between the retina and retinal pigment epithelium 24 h post-treatment. Hence, the role of the surgical technique lies in the development of a sealed chorioretinal adhesion during the first hours postoperatively to obviate the need for face-down positioning. Once the chorioretinal adhesion is sealed, a cho-rioretinal scar will develop postoperatively.
during the first postoperative hours. The need for short- or long-term postoperative tamponading depends on two factors related to the pars plana vitrectomy technique: the use of perfluoro-N-oc-tane and the care with which vitreous dissection is performed around the retinal breaks. The better the peripheral vitreous dissection around the breaks, the shorter the time that is needed to create a sealed chorioretinal adhesion.
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