(a) Fundus photograph of an 18-year-old male with a macula involving combined rhegmatogenous and tractional retinal detachment from toxocariasis. (b) Subretinal band (white arrow) with suspected Toxocara canis organism (red circle)
In dealing with these detachments, whether RRD, TRD, or combined detachments, a wide instrumentation is extremely helpful in facilitating repair. A standard three-port vitrectomy may be used. A thorough vitrectomy with elevation of the hyaloid and scleral depression should be performed. The hyaloid, which tends to be very adherent, should be shaved out as anteriorly as possible, paying particular attention to the margin of healthy and necrotic retina. For these complicated cases, 20-gauge vitrectomy still may be the preferred gauge due to the widest array of instrumentation for repair; however, nowadays the gauge choice may be mostly of surgeon preference, as smaller gauge (such as 23 and 25 gauge) instrumentation and variety have become more plentiful. These smaller gauges may also be better for dissection of membranes. On the other hand, smaller gauges may have higher infusion turbulence and if using perfluorocarbon (PFO) may lead to retained or subretinal PFO (Fig. 3.2).
Retained perfluorocarbon bubble after 23-gauge surgery for repair of a retinal detachment secondary to acute retinal necrosis
Intraoperative complications are increased in uveitis. Careful attention is required to prevent creating retinal holes if instruments are passed through pars plana exudates and posterior breaks during peeling of densely adherent hyaloid and membranes. Attention to tangential peeling rather than anterior-posterior movements may be helpful in preventing unwanted breaks.
Removal of the tractional membranes can be time-consuming and tedious. Some surgeons find staining techniques, such as ICG and brilliant blue, helpful. Kenalog, unless in a noninfectious eye, should be avoided for visualization of the membranes. A bimanual technique may be employed with the help of chandelier lighting. Using PFO may also be useful for applying countertraction while completely the vitrectomy or peeling membranes. If traction remains, retinectomies and retinotomies may be employed. For retinectomies, an endodiathermy edge is created posterior to the traction and atrophic retina into healthy retina and cut. The retina is then treated with endophotocoagulation with several rows. Care should be taken to diathermize blood vessels to avoid excessive bleeding. Cryotherapy can exacerbate inflammation and should be avoided. Scleral buckles may be helpful for peripheral support. Silicone oil is the preferred tamponading agent and remains for at least 3–6 months and sometimes indefinitely (Fig. 3.3).
Postoperative fundus photographs of the patient in Fig. 3.1 demonstrating (a) scleral buckle with residual hemorrhage in the area of the removed subretinal band and (b) flat retina under silicone oil
Removal of subretinal bands can also be arduous and time-consuming. Only those bands causing traction should be removed. Those that are too dangerous to remove may be relieved with the help of a scleral buckle. When they do need to be removed, subretinal bands, such as those seen in toxocariasis TRD (Fig. 3.1), can be a major obstacle. Cautery directly over the band can allow for access for subretinal removal, but the angle for removal may be awkward. Also, by dissecting the band, it may be more difficult to remove. Creating an opening adjacent to the band allows for access as well as use of the tautness of the band to facilitate removal, with or without a bimanual technique (i.e., hand-over-hand extraction). Another technique is to diathermize openings on either side of the subretinal band and using a bent pick to gain access under the band for exposure and removal. Once the band has been externalized, a gentle hand-over-hand technique with two forceps (with chandelier lighting) can be used or a forceps and lighted pick for gentle extraction of the band. Once the retina is flat, laser should be applied to the areas of the tears if possible (Fig. 3.4). If this is not possible, such as in cases with necrosis, laser is usually recommended at the posterior edge of the healthy and necrotic retina to secure the retina.
Postoperative fundus photograph of a patient s/p PPV/SO for repair of a retinal detachment secondary to acute retinal necrosis under silicone oil. Laser surrounding the tear (yellow arrow) and posterior to the necrotic retina
Selected cases of hypotony due to uveitis are amenable to surgical therapy, especially those in which irreversible damage to the ciliary processes has not occurred. Chronic uveitis can lead to the development of cyclitic membranes and hypotony. Should anti-inflammatory therapy fail to reverse hypotony, preoperative assessment of the ciliary body with ultrasound biomicroscopy (UBM) is helpful in identifying the presence or absence of the ciliary processes and the location and thickness of the epiciliary membranes. A thorough pars plana vitrectomy with 360-degree scleral indentation, vitreous base dissection, and bimanual epiciliary membranectomy may affect a sustained rise in intraocular pressure with improved vision in eyes with intact ciliary processes. Endoscopy may be helpful to better visualize the ciliary processes and facilitate removal of the membrane. In those with atrophic ciliary processes, silicone oil may be helpful in preventing phthisis [39, 40].
In the Endophthalmitis Vitrectomy Study, those patients who presented with light perception and had an immediate vitrectomy had better visual outcomes when compared to those with light perception who had a tap only . In these cases, surgical invention should not be delayed to control inflammation. Of course, the patients with vision of hand motions or better did not see the same benefit with immediate vitrectomy. If the endophthalmitis is not postsurgical, whether a tap or vitrectomy is performed, obtaining cultures is important, especially if patients do not appear to be responding to the initial therapies. Here, a good initial clinical workup and judgment are helpful in directing therapy as well.
Vision function after uveitis-associated RDs is guarded. Prognosis is generally poor due to a high rate of PVR and ocular inflammation reactivation, with 70 % of the eyes with <20/200 vision if surgical intervention occurs during active inflammation . While a final reattachment rate of 88 % was achieved using either scleral buckling or vitrectomy techniques, 67 % had a final visual acuity worse than 20/200. This may not only be due to the complication requiring but secondary to the underlying inflammatory cause, especially if optic nerve damage is present.
Complicated retinal detachments are frequently encountered in patients with posterior uveitis. These may be successfully repaired in a high percentage of cases with careful vitrectomy and proper long-term tamponading agents [42, 43]. Tractional complications not infrequently seen in patients with ocular toxocariasis, toxoplasmosis, and pars planitis are best managed with vitrectomy and facilitated with bimanual membrane dissection .
Vitrectomy in uveitis is indicated in the diagnosis and/or correction of surgical posterior segment uveitic complications, such as epiretinal membranes, recalcitrant macular edema, non-clearing vitreous opacities, and more difficult complications like retinal detachments and hypotony. Special circumstances associated with uveitis patients alter surgical planning. The need for control of inflammation pre- and postoperatively is imperative. Though scleral buckles may be acceptable for some rhegmatogenous detachments in uveitis affecting the posterior segment, vitrectomy appears ideal for repair and to possibly reduce the chance of postoperative complications. Surgery for hypotony in uveitis with ciliary body membrane stripping has been reported but is unlikely to be successful if the cause is atrophy of the ciliary processes. A thorough discussion with the patient detailing the guarded prognosis is important as well as managing expectations and controlling inflammation.