Fig. 9.1
Schematic representation of zones and segments of ROP classification superimposed on a clinical image of a stage 4A detachment. If retinal detachment develops, the best chance for a favorable outcome occurs when the detachment does not progress beyond 3 of the 34 segments
This means that fixing initial detachments is the last opportunity of preserving good vision in these babies and that makes stage 4A a therapeutic window that cannot be missed.
In eyes that were treated by laser prior to the development of the detachment, surgical intervention has typically been performed at approximately 40 weeks postconceptional age, classically between 38 and 42 weeks.
If adequate follow-up of the case is possible, adjustments within this range and to this general rule are induced mainly by the presence of active vascularity. The presence of active vascular activity is a serious problem leading to unfavorable surgical results, and thus many authors advocate waiting before performing vitreous surgery until they find a vascularly quiet eye [9, 10, 20, 21]. The use of antiVEGF drugs in recent years has prompted changes in this timing, shifting interventions to earlier postconceptional ages.
In cases of aggressive posterior ROP (AP-ROP), some authors have advocated very early surgical intervention, even performing a vitrectomy before the presence of a retinal detachment [22]. Now it seems more appropriate to first use antiVEGF drugs, which have proved very effective in these very severe cases of ROP [23–28].
Great success rates can be achieved when operating on stage 4A ROP. All efforts should be made not to wait, but to intervene as soon as possible when this diagnosis is made.
Surgical Techniques
General Aspects
As essential as the timing, that is when an operation on ROP patients with retinal detachment should be performed, is how that surgical intervention is carried out. The surgical technique is thus a main element in achieving good results.
There is more than one surgical option to treat a stage 4 retinal detachment. These options include mainly scleral buckling, lens-sparing vitrectomy, and combined lensectomy–vitrectomy. These procedures in turn can be performed with diverse surgical techniques. The use of pharmacological aids might also play a significant role in the management of these detachments, and their use must therefore be taken into consideration.
Each case should be evaluated independently, and all local and systemic factors should be included in the deliberation to decide the best surgical approach for each eye.
The goal in surgical procedures for stage 4 ROP is mainly to stop the shrinkage and traction of the fibrotic tissue developed from the regression of the neovascularization. As previously mentioned, both vitrectomy and scleral buckle can be used to treat stage 4. Considering that vitreous surgery can effectively interrupt the progression of ROP retinal detachment by directly addressing trans-vitreal traction resulting from fibrous proliferation and that when preserving the lens there is much less risk of amblyopia and better chances of central fixation with better vision, lens-sparing vitrectomy is our preferred surgical approach.
Scleral Buckling
Scleral buckling can be effective for treating ROP-related retinal detachments. Different anatomical results and reattachment rates have been published for stages 4A, 4B and 5 [29–32]. With current surgical techniques and instrumentation, vitreoretinal surgery seems a more direct and effective method of addressing trans-vitreal traction. Better results have been reported with vitrectomy for stage 4 when compared to scleral buckling [33]. Adding a scleral buckle does not increase the success of lens-sparing vitreoretinal interventions in stage 4 [34].
Notwithstanding, a scleral buckle can be considered for some cases, particularly when traction is mainly located anterior to the equator. It has also been used in the more effusive types of detachment [35]. These more effusive detachments can sometimes be observed in the acute phase of the disease or following cryotherapy.
Scleral Buckle Technique (Encircling Band)
Like the majority of the authors, we favor the use of an encircling scleral buckle (Figs. 9.2, 9.3), although others have reported successful outcomes using segmental scleral buckling [32].
Fig. 9.2
Image of a scleral buckle, a 2.5 mm solid silicone band. A good scleral indentation can be observed
Fig. 9.3
Picture of the posterior pole of a case with stage 4A in a Zone I ROP treated with a scleral buckle taken one year after surgery. Despite distortion of the macular area a 20/60 vision was observed at the age of 14 years in this patient
The technique of scleral buckling in our ROP patients involves:
360° peritomy at the limbus, isolation of the four rectus muscles follow by a silk suture passed under each of them for handling.
A cotton tip is used to strip the sclera in all four quadrants.
A 2.5 mm # 240 solid silicone band is sutured to the sclera using 5-0 non-reabsorbable sutures. The band is placed at the equator and supporting the ridge when possible.
Proper tightening is done by performing a paracentesis with a 30 gauge needle mounted in a tuberculin syringe to drain aqueous fluid. The perfusion status of the central artery should be checked after the final tightening of the band.
Although the anatomical success rate of buckling procedures can be fairly good, the functional results are much worse. Encircling buckles induce myopic refractive changes that can be very high and thus potentially amblyogenic. Additionally, possible negative effects of the encircling band on choroidal circulation should be considered. The eye grows significantly during the first year so a moderate buckling effect at the time of surgery can lead to much greater constriction over time. To address this problem, division or removal of the band is recommended when stable retinal reattachment is achieved. [36]. This is usually done after 6 months if retinal reattachment is stable or in cases of anisometropia, however it seems logical to delay the removal in unstable situations. A two-step intervention with elongation of the buckle has also been proposed to allow an almost constant buckling effect during the first year of life [37].
Concerns regarding amblyopia with scleral buckling, improvements in surgical techniques and instrumentation, the very infrequent use of cryotherapy leading to effusive cases and the availability of antiVEGF drugs as adjuncts for intraocular surgery have placed buckling as a second choice as opposed to vitrectomy for stage 4 ROP.
It must be emphasized that reattachment of the retina after a buckling procedure for ROP is a slow process that can take several weeks to settle.
Vitrectomy
There are different technical approaches to performing vitreoretinal surgery for retinal detachments in ROP. The surgery can be done using two or three ports and be either standard 20 gauge or micro-incisional vitrectomy surgery. There might not be a preferred technique and at the end it is mostly surgeon-dependent. Each surgeon should use the technique that produces the best possible results in his/her hands.
A careful preoperative examination will allow the best entry site to the vitreous cavity to be chosen. An open space between the retina and the lens is necessary to perform a lens-sparing vitrectomy. If there is advanced anterior retinal traction there is a high risk of causing a retinal break, and an anterior approach should be selected.
Lens-Sparing Vitrectomy (LSV)
Surgical technique to perform LSV using a 3-port, 25-gauge trans-conjunctival sutureless approach:
Sclerotomies are made 0.5–1.0 mm posterior to the limbus through the pars plicata. In the first place, the conjunctiva is displaced immediately above the sclerotomy site and the cannula is inserted into the vitreous cavity using a beveled trocar. This procedure is applied to place the cannulas in the temporal, superotemporal, and superonasal quadrants. The infusion cannula is placed in the temporal quadrant while the superotemporal and superonasal ports are used to pass the light pipe and the cutter.
Vitrectomy and membrane peeling are performed with settings of >1500 cpm and a suction of 500 mmHg. The cutter must be used very cautiously to avoid any iatrogenic breaks. If a rhegmatogenous component is added during surgery, the chances for a successful outcome are dramatically reduced.
The aim of the vitrectomy is to dissect the tractional proliferation between the ridge and the lens, the ridge and the nerve, the ridge and the vitreous base, and the circumferential traction along the ridge.
A partial fluid-air exchange is performed at the end of the procedure in the majority of cases. When fluid is left in the vitreous cavity, the infusion cannula is removed at the last step to check for the need for further infusion.
The conjunctiva is closed using a bipolar diathermy.
Lensectomy–Vitrectomy
Lensectomy–vitrectomy will be performed in a stage 4 ROP when anterior traction does not make lens sparing a safe choice. Although LSV is the preferred method, it always has to be clear that it is better to remove the lens than to make an entry site break. When the lens is removed, good visual acuity is much less likely. Amblyopia is in most cases severe and difficult to treat. Nonetheless it is important to consider that after a vitrectomy for stage 4 ROP, continuing improvement of vision development can occur over long periods of time. Restoration of the retinal architecture and the plasticity of the infant’s developing brain are thought to play a role [38].
The entry site for lensectomy–vitrectomy surgery will be the limbus, just above the plane of the iris root. This will allow for safe removal of the lens and intravitreal maneuvers. Twenty three-gauge instrumentation can be successfully used in pediatric conditions [39, 40], and it might be a good selection of instruments for these cases. Entry sites should be sutured with 10-0 nylon at the end of the procedure.
The small gauge instrumentation currently available allows for effective and safe vitreoretinal procedures (Fig. 9.4). Initial problems such as instrument flexibility and adequate illumination have been resolved. The use of a specific gauge or a combination of different instrumentation should be available to allow the surgeon to choose the best alternative for each particular case.
Fig. 9.4
Pre (a) and postoperative (b) images of the left eye of a preterm born at 29 weeks and 1.200 g that developed a stage 4A retinal detachment that was managed with a vitrectomy performed with 25 gauge instrumentation
Complications of Vitreous Surgery
Hemorrhage: Intra- and postoperative bleeding greatly increases the risk of failure of any intraocular surgical procedure in ROP-related retinal detachments. Eyes that have not had peripheral ablation and that have perfused fibrovascular tissue at the time of surgery are at the highest risk of bleeding. Waiting for spontaneous regression of the neovascular activity was done prior to the availability of antiVEGF drugs.
Hypotony: This can occur during a vitrectomy, and it should be prevented by the use of adequate instrumentation. Avoiding hypotony when using a two-port approach can be challenging and requires great experience. The use of a third port can help to maintain more stable intraoperative pressure. Although trans-conjunctival sutureless vitrectomies using small gauge instrumentation works very well, if there is doubt regarding leakage from any of the entry sites, then a suture should be place to secure the eye closure. The closure of the conjunctiva with a bipolar diathermy in all sutureless cases might also help to prevent hypotony. When the entry sites are through the limbus they should always be sutured.
Retinal breaks: ROP surgery poses a very significant challenge to the surgeon. It is well known that the chances of anatomical success are very small if there is a rhegmatogenous component added to the detachment. If a break is formed during a vitrectomy, the complete release of the traction associated with the break is needed for the surgery to have any chances of success. Special attention must be paid not to induce an entry site break when an anterior proliferation is present.
Endophthalmitis: This is a potential risk in any intraocular intervention. Using all the standard preoperative measures, suturing limbal entries and closing the conjunctiva with bipolar diathermy in cases of a sutureless approach should prevent it.
Glaucoma: Pressure elevation can occur in the immediate postoperative period, but adequate surgical techniques should make this problem infrequent. Postoperative glaucoma could be a late complication after ROP retinal detachment surgery. [41] Follow-up that includes measurement of the intraocular pressure should be performed in these children.
AntiVEGF Drugs in the Management of Rop Retinal Detachments
The use of antiVEGF drugs in ROP has prompted changes in the management of ROP-related retinal detachments. These drugs might help in the management of patients who already have a detached retina, but they have also created a new category of retinal detachments, those that can develop after using anti-angiogenic agents to treat the acute stages of the disease.
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