Although the eye seems to get by without the vitreous after its removal by PPV, this transparent crosslinked hydrogel plays an important role in mechanical and molecular homeostasis of the eye.20–22 Indeed, due to presence of the collagen, the hyaluronan and their interactions, the vitreous body has viscoelastic properties that allow it to absorb energy rapidly and release it slowly. In addition, the normal vitreous, probably related to the high level of ascorbic acid, keep the oxygen levels low.21 Hence, the increased oxygen levels in vitreous chamber after vitrectomy lead to an oxidative stress that may results in cataract, late-onset open glaucoma and PVR.23–25 Moreover, another content of the vitreous, the thrombospondin, seems to be responsible of its antiangiogenic and antineoplastic features.22
Under this light, a vitreous sparing procedure could be thought as a reasonable option in the management of RRD. Nevertheless, vitreous-sparing procedures, SB and PR, presented some issues which make PPV the most performed surgical procedure for RRD in most of the world. 13
SB, although recent studies have reported a high anatomical success (53–83%), still remains a complicated surgery with a high risk of intraoperative and postoperative complications.5,9 On the contrary, PnR is a simple and minimal invasive procedure, but, in terms of efficacy, recent studies have shown a primary success rate between 73% and 81%, while lowering in aphakic and pseudophakic eyes (41–67%).7,26,27 Indeed, after this procedure, the discovery of new retinal tears or the visualization of other tears not previously identified were very common (12–23%).6 This aspect seemed related to the no wide-angle visualization and to the stretching of the vitreous from the growing gas bubble in a limited space, generating tractions in other areas of the retina and leading to new breaks. Therefore, this intervention still remains recommended for selected cases, such as eyes with a RRD due to a single small retinal break or a group of breaks within 1 hour within the superior 8 clock hours of the retina.28
Actually, PPV is performed for the majority of RRDs and resulted very successful. According to the two large comparative randomized studies of Heimann et al (PPV against SB) and Hillier et al (PPV against PnR), the primary anatomical success for vitrectomy was of 72% and 93%, respectively.7,9. Nevertheless, PPV is associated with specific complications, such as iatrogenic retinal tears, lens touch, cataract formation, CME and increased IOP. 24,29–31 Moreover, the time of surgery and manipulations inside the vitreous chamber could influence the complication rates, such as phototoxicity.32
For all these reasons, the development of less invasive techniques has been investigated in recent years. In 2018, Bonfiglio et al. have published their experience of a localized vitrectomy with a 94% of success for a single surgery and 100% success after additional procedures for 32 eyes affected by macular ON detachment.16 The technique described by the authors has involved the use of three 25G trocars to remove the vitreous tractions around the retinal rupture under air (continuous infusion at 30-35mmHg) and to drain the subretinal fluid through the rupture, then treated with an endolaser. No central vitrectomy or "shaving" of the vitreous base has been performed.16 Whereas, a similar procedure, called “minimal interface vitrectomy” and characterized by a sectorial vitrectomy (25G) under air (continuous infusion at 35mmHg), has been described by Mura et al.15 Differently from the previously described technique, this procedure included a partial vitrectomy in the center of the vitreous chamber to allow adequate tamponade with air or gas (SF6). The authors reported an anatomical success of 100% on 12 eyes. 17
The aim of our study was to develop a different surgical technique for the management of a RRD, comparable to PnR in terms of vitreous preservation and surgical timing, and at the same time similar to three-ports PPV in terms of efficacy and safety. Compared to the standard PPV, our procedure has several advantages. First, considering the average operation duration of 8.61 ± 2,16 min, it has reduced the total surgical time. Our two-port dry vitrectomy was rapid and used less incisions and minimal vitreal manipulation with a supposed reduction in inflammatory response. Consequentially, no PVR or anterior chamber inflammation has developed in any of our patients during the follow-up period.
Similarly, considering all the twenty eyes of our study, no postoperative CME has been recorded, which represents a common complication in standard PPV.33 In fact, recent studies highlighted an higher incidence of CME after RRD repair with PPV, either alone or combined with phacoemulsification, than SB. [16] Probably, also the use of cryotherapy retinopexy instead of endolaser retinopexy, plays a role in lowering the risk of postoperative CME.31 Furthermore, limited vitreous removal with preservation of cortex which protects the crystalline lens from an excessive oxygen exposure, reduces the cataract formation.23 Indeed, in our population no opacification of the lens has been observed during the follow-up.
Comparing with the other localized PPV procedures [12, 15], the innovation of our two-port dry PPV is to remove the vitreous surrounding the retinal breaks without any infusion and vitreal hydration. Consequentially, we preserve the vitreal gel with his structure and antioxidant properties to reduce the onset of postoperative inflammation, and, simultaneously, we removed the colliquated vitreous under the retina in order to create the space for the gas to expand and to reduce secondary tractions on other areas of the retina.
In conclusion, our novel technique resulted in 85% of anatomical success, with a statistically significant improvement of BCVA in macula off patients. No postoperative complications have been recorded, except for three retinal re-detachments. The main limitations of this study are the small number of patients enrolled, the selection of only uncomplicated RDs and the short follow-up time. Moreover, the lack of the patient monitoring during the postoperative follow up to ensure a strict head position, represents another limitation. Indeed, we considered this aspect as mandatory. Although further studies are necessary, we believe that our minimal two-ports dry vitrectomy could be considered a valid alternative to treat primary RRD, with high efficacy and safety profile.