Causes of retinal re-detachment after PPV include the following: PVR; factors associated with breaks such as ineffective closure of preexisting breaks, large breaks, opening of old breaks formation of new breaks, reopened macular hole, and progressive vitreoretinal traction; incomplete removal of the vitreous base and shaving; inadequate retinal tamponade not adhering to the strict continuous posture; and perisilicone proliferation. The most common cause of recurrent RD is PVR[10]. Contraction of PVR may cause retinal foreshortening, which can exert anteroposterior, perpendicular, and/or circumferential traction on the retina, particularly near the vitreous base[3]. Furthermore, foreshortening of the retina may prevent retinal reattachment. SB can relax the tractional forces on the retina, thus reattaching the retina effectively. All our 14 cases had PVR, and at the last follow-up, 13 of the 14 patients achieved anatomical success, supporting the importance of relaxing the tractional forces when reattaching the retina.
In a review[11], Edwin and Robert analyzed the continued role of SB in the vitrectomy era. They found that significant skill and practice is required to correctly place the SB elements with the desired indentation to support the retinal tears and to drain the subretinal fluid without complications. In our research, the RD were not primary retinal detachment, but re-RD with PVR. Nevertheless, we had a high success rate. This could be attributed to the surgeon’s experience and careful patient selection. Generally, the criteria for case selection are as follows: (1) The (probable) retinal tear is on the periphery; (2) There is no obvious proliferative traction in the posterior retina; and (3) The height of RD is low. Patients with funnel-shaped RD cannot undergo this surgery.
RD in post-vitrectomy eyes can progress rapidly, which can easily lead to PVR. Furthermore, if another PPV is performed to attach the retina, silicone oil may be used, often causing the eye to become oil-dependent. Furthermore, the presence of silicone oil does not guarantee retinal reattachment. The recurrence rate of RD in silicone-oil filled eyes is 22%[12]. The postoperative complications associated with using silicone oil occur both in the anterior and posterior segments, including keratopathy, cataract, glaucoma, silicone oil toxicity in the retina[12, 13]. The longer the silicone oil remains in the eye, the more complications arise. Some authors have reported extraocular extension of silicone oil into the brain 15 months after silicone oil tamponade in the eye[14, 15]. The risk of re-RD is 34% after removal of silicone oil[6]. It is thus important to study the outcomes of other interventions to understand whether performing repeated vitrectomy on patients with a history of failed surgeries is worthwhile. Our research on re-RD in post-vitrectomy eyes with prior RRD demonstrated the benefits of SB.
Twelve out of 14 patients (86%) achieved anatomical success after one operation and 13 out of 14 patients (93%) achieved final anatomical success, which is comparable with previous re-vitrectomy + retinectomy + gas or silicone oil tamponade reports that showed a reattachment rate of 60% to 90%[2, 3, 8, 10]. The inability to detect retinal breaks in a RRD has been reported to be associated with a poor prognosis[16]. In our patients, no clear breaks were detected in 7 eyes preoperatively. Six of the 7 eyes were pseudophakic and the remaining one eye was aphakic. Five of the 7 eyes had suspicious holes and 2 eyes had no visible break during the operation; nevertheless, retinal reattachment was successful in all these cases, which indicated that re-RD without detecting a break is not a contraindication for SB. The reasons why breaks cannot be detected are as follows: the IOL occludes some small breaks, the break is too small to be found, the RD is too high and the break is hidden in the PVR, or there is no break present.
Despite having undergone a mean of 3.29 surgeries at the last visit, 5 (36%) of our 14 patients still had a final BCVA≥0.4 LogMAR (Snellen 20/50), which is also promising compared with previous reports[9, 10, 17]. Macular involvement with RD is a known risk factor for a limited visual outcome[5, 16]. In our cases, 7 patients had macula-on retinal detachment. One eye maintained the preoperative vision, 5 eyes had improved vision, with the best BCVA reaching 0.1 LogMAR (Snellen 20/25), and one eye had decreased vision because of failure to reattach the retina.
The advantages of SB for treating recurrent RD after PPV are mainly as follows: (1) It alleviates damage to the eye using minimal surgery compared with PPV. (2) It does not interfere with the intraocular tissue (SB is an external operation), which can reduce irritation to the posterior retina, thus protecting the macula to some extent and improving vision recovery after operation. (3) Patients need to be in a prone position for no or a short time after operation if combined with gas injection, thus relieving the patient’s suffering. (4) Repeated PPV procedures are inherently more expensive than SB, and it increases difficulty in operating and usually leads to silicone oil dependent eyes, causing both economical and emotional burden. Moreover, the presence of silicone oil does not guarantee correct retinal positioning, with an RD recurrence rate of 22%[12].
The disadvantages of SB for treating recurrent RD after PPV are mainly as follows: (1) SB greatly differs from PPV, and there is a significant learning curve. Experience with many cases is required to accurately select the most effective elements[11]. Therefore, both proficiency in indirect ophthalmoscopy and caution when performing SB procedures are necessary. Experience and correct technique to treat complications are necessary. (2) Ocular surface inflammation is more severe after SB, but it quickly recovers. (3) It is more likely to cause high IOP and anterior segment ischemia syndrome compared with PPV. Though the chances are low, irreversible visual impairment can be damaging. (4) The buckle material can cause some changes in the eyeball structure, inducing myopia and astigmatism[18].
Improvements in the instruments used for vitrectomy and the introduction of 25-gauge vitrectomy has decreased the necessity of suturing. Hence, it may have increased the surgeons’ preference to perform vitrectomy over SB[18]. Nevertheless, multiple PPVs may not always be the best strategy for patients, and SB may be more beneficial.