Ординатура / Офтальмология / Учебные материалы / Ocular Traumatology Springer

Fig. 2.9.7  Removal of a subretinal strand in an eye with PVR. In this intraoperative photograph, a subretinal strand that is too thick and elastic to allow retinal reattachment is being removed with forceps. The retinotomy has been created right on top of the strand

–If the strands do not permit retinal reattachment and no retinal break exists, a careful site selection for the retinotomy58 is needed.

–Issues to consider include: dexterity of the surgeon;59 proximity of the strand to the macula and major blood vessels;60 and the likely choice of tamponade61.

–It must also be decided whether the retinotomy should be right on top of the strand (Fig. 2.9.7) or at some distance from it; the latter has the advantage of allowing more room for manipulations, but it may be more difficult to firmly grasp the strand.

–The gravest danger during subretinal manipulations is choroidal injury and hemorrhage. All maneuvers must be performed with great caution.

58More than one retinotomy may be required.

59The dominant hand’s side is preferred.

60The retinotomy should be as far away from the macula and from major blood vessels as possible.

61A site superior to the horizontal plane is recommended, especially if gas, rather than silicone oil, is to be used as postoperative tamponade.

surgeon works elsewhere, and is extremely useful when posterior subretinal fluid should be evacuated through a peripheral retinal break or a giant retinal tear must be flipped back.

The PFCL should not be used in eyes with a posterior break in the presence of residual traction or in an eye with a closed funnel (see above).

2.9.5.5.3 Tamponade

In almost all cases of vitreoretinal surgery for a serious injury, a tamponade is left in the eye. The tamponade helps keep the retina attached by resisting traction and by blocking the subretinal access of intravitreal fluid trough a retinal break.64

ZPearl

For eyes with serious posterior segment trauma, silicone oil, not longacting gas, is the preferred tamponade.

With regard to silicone oil tamponade:

•If it is possible to know before surgery that silicone oil will be used, it makes sense to determine the eye’s axial length. The measurement is much less reliable in a silicone oil-filled eye. The reading comes handy when the silicone oil is removed; simultaneous IOL implantation can be performed should the lens become cataractous and be extracted at the time of silicone oil removal.

•Implant the silicone oil after a fluid−air exchange to achieve a complete fill.65

•There is BSS lining the retinal surface; it takes time for this fluid to collect at the disc during fluid−air exchange (Table 2.9.6). It takes much longer for this BSS to “trickle down” to the bottom of the eye if there

64Detailed discussion of the indications for, and selection of, different tamponade options is beyond the scope of this book. Table 2.9.6 shows selected suggestions regarding intravitreal exchanges.

65100% is not feasible, but the fill should be as close to it as possible.

12  Similar to a coffee mug: after all the coffee is thought to have been swallowed, it quickly accumulates at the bottom once the mug is replaced on the table.

13  Gas tamponade must not be used if the patient lives at high altitude or is expected to fly on airplanes while the gas is in the eye (see Chap. 3.3).

14 The rare exception is when the eye was completely filled with PFCL first.

is silicone oil, rather than air, in the vitreous cavity. In addition, visualizing the BSS/silicone oil meniscus is much more difficult than the BSS/air meniscus.

•Prophylactic removal of the lens66 should be considered if the silicone oil is to be kept in the eye for extended periods of time. Serial ophthalmoscopic examinations (i.e., direct retinal inspection) are crucial in eyes with silicone oil and a cloudy lens is as aggravating for the surgeon as it is for the patient.

•If the lens is removed before silicone oil implantation, extracting the lens in toto should be considered (see Chap. 2.7). The posterior capsule is likely to become at least somewhat cloudy, and silicone oil may find its way around the zonules and prolapse into the AC.67 If this complication occurs, the only option the surgeon has is to inject cohesive viscoelastic into the AC68 and simultaneously evacuate the silicone oil.69 The viscoelastic must be left in the AC: it will be absorbed within a few days.70 The IOP must closely be monitored and prophylactic antiglaucoma medications should be used for a few days.

66Especially in older patients whose eye has already lost accommodation capability

67High myops are especially at risk.

68Filling the AC with a cohesive viscoelastic before silicone oil implantation should always be considered (see Chap. 2.5).

69A small silicone oil can be left behind in the AC. As long as it has enough room to be mobile, the threat to the endothelium is minimal.

70Silicone oil prolapse will or will not recur.

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•A peripheral inferior iridectomy must be created with the vitrectomy probe before oil implantation, preferably after diathermy to prevent bleeding. The iridectomy must be sufficiently large;71 its subsequent scarring and thus closure of the iridectomy is a common cause of secondary glaucoma.

•For most cases, 1000 centistokes silicone oil will suffice. If the tamponade is felt to be necessary for several years, 5000 centistokes silicone oil is preferred. A more viscous silicone oil is more difficult to inject and remove.

•The aim is a 100% silicone oil fill (see above). The surgeon should check the IOP before removal of the infusion cannula72 and the optic disc for circulation patency.

•If PVR recurs under silicone oil but the macula remains attached (see above), there is no urgency to reoperate unless the detaching retina pushes the oil into the AC or the retina suffers a tractional break73 and silicone oil is found subretinally74. If any of these complications occur, a reoperation is necessary to remove the proliferative tissue and reattach the retina. It is the surgeon’s preference whether the reoperation is performed under oil or after a silicone oil−fluid exchange. The latter has the advantage of “oil change,” which starts the “emulsification cycle” anew. Removal of the subretinal silicone oil is difficult and does require removal of the intravitreal oil first; PFCL is not helpful in removing subretinal oil, which can be achieved only by active aspiration (e.g., using the flute needle or the vitrectomy probe).

71A judicious posterior capsulectomy must also be performed in the area of the iridectomy.

72Mild IOP elevation is actually preferred over a normal or low value to compensate for temporary space-filling factors such as tissue edema and residual intravitreal fluid.

73This is recognized by its characteristically oval shape and typically very large size.

74As the detaching, rigid retina pushes against a resistant silicone oil and the retina finally tears, it “bypasses” the oil, which thus takes on an hourglass shape.

•Removal of the silicone oil from a traumatized eye should not be rushed. The PVR and retinal detachment can occur as late as several months post-injury. For the removal, silicone oil-BSS exchange is advised, followed by several fluid−air exchanges to reduce the number of silicone oil droplets left behind.75 Endoscopy-assisted vitrectomy is able to achieve a more complete job (see Chap. 2.20). The oil may also adhere to a silicone IOL, making removal very difficult (see above and Chap. 2.7).

•If the ciliary body sustained irreversible damage, silicone oil is the surgeon’s only option to prevent phthisis (see Chap. 2.19). In these eyes the fill must be “100% and some more”: the entire globe (i.e., including the AC) is to be filled and the IOP set at ~30 mmHg. The cornea, paradoxically, has a better chance of remaining clear with a complete fill since if any aqueous is produced, it is unable to gain access to the damaged endothelium.76

2.9.5.5.4 Use of Retinal Tacks

Although retinal tacks are much less popular than a decade or so ago, they are an excellent intraoperative tool, and they are well tolerated in the eye long term [70].

2.9.6Small-Gauge Vitrectomy in Ocular Traumatology

Small-gauge vitrectomy77 is advantageous in many elective conditions for both patient and ophthalmologist. It has, however, certain disadvantages:

75Complete oil removal is not possible because tiny droplets will remain hidden at inaccessible places such as behind the iris.

76Eventually, the cornea will become cloudy or the silicone oil will emulsify. A corneal specialist must be consulted whether DSAEK or PK is to be performed. The silicone oil should be reimplanted. EDTA may also bring temporary clearing.

7723 or 25 g

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the armamentarium is still not the same as for the standard 20-g systems; the instruments have a tendency to bend, making intravitreal manipulations more difficult; the speed of vitreous removal is slower; and the use of a cannula inherently limits the size of instruments that can be inserted into the eye. Furthermore, the real advantages78 of the small-gauge system offer no benefit to the patient with a traumatized eye.

2.9.7Retinal Injury: Prophylactic Measures

In eyes with scleral wounds located in Zone 3, the occurrence of a retinal injury must always be considered. The need to prevent retinal detachment using prophylactic laser treatment, cryopexy, and/or scleral buckling is still debated.

2.9.7.1Prophylactic Laser Treatment

Endolaser cerclage79 is a very reasonable recommendation in eyes undergoing vitrectomy for trauma. The procedure creates a new ora serrata (Fig. 2.9.8) with a very low complication rate80 but offers substantial benefits [63]. This new ora serrata is likely to encompass the entire area where retinal tears develop. It also destroys tissue that may be responsible for the release of inciting agents partially responsible for PVR development. Performing laser cerclage during surgery as a prophylaxis means that subsequent opacification of the media will not interfere with laser delivery if it were to become necessary for a newly developing pathology.

78There is need neither for lengthy wound preparation nor for wound closure at the end of surgery.

79A term coined by R. Morris, Birmingham, Alabama.

80EMP in 1−3% and occasionally mydriasis if the two horizontal meridians received too heavy treatment.

Fig. 2.9.8  Endolaser cerclage. Vitrectomy has been performed in this eye for a contusion-re- lated vitreous hemorrhage. A new ora serrata has been created to prevent retinal detachment from a potential (unidentified) retinal break. Such breaks can occur years after the injury but may also be caused by the surgery itself

2.9.7.2Prophylactic Cryopexy

The rationale behind the procedure is to seal any retinal break that may have occurred or would subsequently develop underneath the scleral wound. There are several possible scenarios, which are shown in Table 2.9.7.

ZCave

Cryopexy to prevent retinal detachment in eyes with a visible retinal break is not recommended; laser retinopexy should be used instead. Cryopexy is contraindicated if its effect on the retina cannot be monitored due to media opacity.

2.9.7.3Prophylactic Scleral Buckling

The rationale for placing a scleral buckle over a freshly closed scleral wound is to prophylactically counter any traction that may subsequently originate from the wound area.