Drainage of subretinal fluid during rhegmatogenous retinal detachment repair allows for immediate apposition of the retinal break against the retinal pigment epithelium. This enables endolaser uptake during vitrectomy and facilitates scleral buckle tightening during repair with primary scleral buckling. The optimal way to drain subretinal fluid during vitrectomy remains a debated topic. The most common techniques include draining through a preexisting retinal break, creation of a drainage retinotomy, and the use of perfluorocarbon liquids. Each technique has its benefits and possible complications. The surgical approach often depends on the characteristics of the retinal detachment, surgeon preference, and cost factors.
External drainage, perhaps the oldest technique of draining subretinal fluid, is primarily used during scleral buckle procedures. Conventionally, scleral cut down with diathermy of the choroidal bed is performed with the surgeon observing the egress of fluid externally. External needle drainage under direct visualization was first described by Charles1 in 1985. Since then, many modifications to this technique have been proposed, including the use of a guarded needle.2 More recently, chandelier-assisted drainage under direct visualization with a widefield noncontact lens during primary scleral buckling has been reported.3,4 Despite continued improvements in external drainage techniques, this approach has largely been ignored in the setting of vitrectomy.
In this report, we describe a technique of transscleral and transconjunctival external drainage during vitrectomy with or without concurrent scleral buckling for repair of rhegmatogenous retinal detachments and present a case series of six patients.
For repair with primary vitrectomy, standard pars plana vitrectomy is performed with a 25-gauge trocar-based system (Alcon Laboratories, Fort Worth, TX), followed by identification of retinal breaks. All breaks are then marked with diathermy. A Hanscom needle (Beaver-Visitec International, Waltham, MA) is then connected to the extrusion line to better control the rate of subretinal fluid drainage with foot pedal control. This is a commercially available 25-gauge curved needle with a reverse bevel tip and a silicone sleeve that is 3.5 mm from the tip (Figure 1). Alternatively, this can be fashioned from a standard 25-gauge needle and a silicone buckle sleeve.2 Next, the needle is advanced into the fornix in an area of planned drainage followed by direct visualization of the scleral indentation through a wide-angle viewing system with the light pipe (Figure 2). Once the location of the needle tip is positioned correctly and away from larger choroidal vessels, the needle is advanced transconjunctivally into the subretinal space (Figure 3). The foot pedal is then used to modulate a slow and steady extrusion. For small breaks, the drainage process may be completed with the infusion still on fluid. For larger retinal breaks, the infusion is first switched to air to prevent fluid from continuously entering into the subretinal space. The drainage needle is then withdrawn once subretinal fluid drainage is complete. Finally, a complete fluid–air exchange is performed with a standard soft-tipped extrusion cannula.
For combined buckle-vitrectomy, a 360 peritomy is performed and the scleral buckle sutured into place. The drainage needle is then introduced into the subretinal space transsclerally in similar fashion (see Video, Supplemental Digital Content 1, http://links.lww.com/IAE/A850, which demonstrates surgical technique).
In our series of 6 patients with rhegmatogenous retinal detachments, the average age was 64.3 (±SD, 10.7). Of the six patients, four were men and two were women. All cases were macula-off at the time of surgery. Five patients underwent vitrectomy alone and one patient underwent combined buckle-vitrectomy. Of the five vitrectomies, one patient had a chronic detachment (>1 month) with primary proliferative vitreoretinopathy (PVR) and one patient had postendophthalmitis-associated detachment. Both eyes developed PVR and redetached, and required two procedures for successful reattachment. There were no cases of choroidal/subretinal hemorrhage or retinal incarceration.
External drainage, despite many improvements over the past decade, has largely been relegated to primary scleral buckling procedures. In this report, we propose a technique of transscleral or transconjunctival drainage during vitrectomy with or without the addition of a scleral buckle. This technique might be ideal for bullous retinal detachments with very small retinal breaks, such as in some pseudophakic detachments. In these cases, drainage through small breaks may not be possible and the creation of additional retinal defects for drainage is not ideal and may potentially increase the risk of PVR. In addition, removal of subretinal fluid and associated retinal pigment epithelium cells using an external approach without exposure to the vitreous cavity may theoretically lower the risk of PVR.
Chen et al5 recently described the use of external needle drainage during combined vitrectomy scleral buckling for the treatment of bullous exudative detachment, schisis detachment, or cases of bullous retinoschisis. In these challenging cases of severely bullous detachments where trocar insertion is at risk of injuring retinal tissue, external drainage can be a valuable technique to flatten out the retina before vitrectomy. Our series demonstrate that this technique can also be performed transconjunctivally without a peritomy or addition of a scleral buckle.
With the conventional method of scleral cut down external drainage, the most dreaded complications include subretinal and choroidal hemorrhage as well as retinal incarceration. Positioning the needle away from larger choroidal vessels and vortex veins can minimize the risk of hemorrhage. By using a guarded needle and indenting the sclera, the position of the needle can be verified before it is advanced into the subretinal space. In addition, the sleeve around the needle lowers the risk of the needle entering too far and perforating the retina. The risk of hemorrhage is further reduced when external drainage is performed with vitrectomy because the eye remains pressurized by the infusion cannula. Small hemorrhages may be controlled by elevating the intraocular pressure immediately. The risk of retinal incarceration is minimal with the use of a reverse-beveled needle under direct visualization.
In our limited series of six patients, there was a relatively high prevalence of redetachment. However, both were high-risk cases where one had endophthalmitis-related detachment with postoperative PVR and the other was a chronic detachment with PVR at the time of initial surgery. External drainage was used in both cases to potentially reduce the already high risk of PVR but both cases ultimately required a second procedure to achieve reattachment.
In summary, we report an alternate method of removing subretinal fluid using external needle drainage during vitrectomy with or without scleral buckle for the repair of retinal detachment. This technique avoids creation of additional retinal defects and use of perfluorocarbon liquids. In addition, it theoretically minimizes the exposure of retinal pigment epithelium cells to the vitreous cavity, potentially lowering the risk of PVR; however, additional studies will be needed to confirm this benefit.
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