33.1Retinectomy

Retinectomy is a procedure where a part of the (detached) peripheral retina1 is removed. The two major indications include retinal shortening or a retina with inseparable vitreous and/or membranes on its surface. A retinotomy should always precede the retinectomy, making the selection of the characteristics of the retinotomy the primary issue in surgical planning. There are two important questions to answer: location and length (see below).

The decision to perform a retinectomy should never be taken lightly; the “carpenter’s rule” (see Sect. 32.6) is especially true for this procedure. Reproliferation on the remaining central retina, whether due to a retinectomy done improperly (see below) or just as a natural process, may cause the remaining retina to “roll up like a rug” – a condition very difficult to treat.

Q&A

Q How do you determine the ideal location of the retinotomy?

AThere are two antagonistic principles. On the one hand, the further anterior the site, the smaller the loss of the peripheral visual field. On the other hand, the surface of the remaining retina (i.e., central to the retinotomy) must be clean of all material. Leaving vitreous or membranes on the retina increases the risk of reproliferation, which is even more difficult to treat than usual. The more central the retinotomy, the more likely that no vitreous or membrane is left on the remaining retinal surface.

1 “Peripheral” here means a retina that is peripheral to the retinotomy (see below), not necessarily a retina anterior to the equator.

F. Kuhn, Vitreoretinal Surgery: Strategies and Tactics,

DOI 10.1007/978-3-319-19479-0_33

Q&A

Q How do you determine the necessary length of the retinotomy?

AIt can vary between a few clock hours to 360°. The golden rule is: “A little more won’t hurt, a little less might.” It will be at the edge of the retinectomy (where the circumferential line turns toward the periphery) where it may become stretched and start to redetach. If any traction is experienced during the air test (see Sect. 31.1.2) or PFCL implantation, extend the retinotomy further. A crucial issue is to decide between 350° and 360°. In the latter case the entire retina can be twisted around the optic disc as the anchor point, which poses technical difficulties but also offers advantages (see below).

•Create a PVD and remove all epiretinal membranes as far to the periphery as possible. With few exceptions, the retinotomy is done along a line that is more or less parallel with the ora serrata.

•Apply diathermy in an arching line, marking the site of the retinotomy, central to the line where vitreous/membrane vs retina separation was impossible: any vitreous or epiretinal proliferative tissue still present must remain anterior to this line. If the retinotomy is less than 360°, make sure that the edges reach the ora serrata.

– Use high diathermy power so that all blood vessels, especially the larger ones, are closed.

– If this is a reoperation and proliferative tissue is present anterior to the retinotomy line, blood vessels may feed the conglomerate from anteriorly; in such cases either be prepared to deal with the occasional hemorrhage or, preferably, create a more peripheral second diathermy line.

– The diathermy tip of most probes are not Teflon-like: the burnt tissue will stick to it and the tip needs to be cleaned repeatedly. You can do it inside the eye with the light pipe (see Sect. 32.1.3), or hand it over to the nurse.

– The small air bubbles created by the diathermy process will gather behind the lens (see Sect. 27.5.3).2 These bubbles will interfere with visualization and thus need to be removed from time to time.

•Cut the retina in the middle of the diathermy line (not outside it so as to prevent bleeding).

– Cutting it with scissors3 is safe because it is fully under the surgeon’s control, but time-consuming in MIVS.

– Cutting it with the probe is much faster but more difficult to control. The risk is that the probe bites into the retina that has not been diathermized and will

2The cornea in the aphakic eye.

3Especially if smaller than 20 g.

Fig. 33.2 360° retinectomy, postoperative image. The retina is attached under silicone oil; there is no PVR reaction. The line of retinotomy was very posterior – the patient presented with bare LP vision 3 months after a large rupture and total retinal incarceration

Table 33.1 Silicone oil implantation after 360° retinectomy if PFCL-fluid mixture (“fluid sandwicha) is in the vitreous cavity

aThis is why a 100% PFCL fill is preferred.

bAspirating the PFCL first may cause retinal redetachment and is thus not recommended.

cThe surgeon must monitor the optic disc, and if the vessels are pulsating, stop the injection. If the disc turns white, it is very likely that the oil has been aspirated into the flute needle.

dHence the need to inject the silicone oil at low pressure – the BSS removal becomes equally slow, thus greatly reducing the risk of aspirating the retinal edge into the flute needle.

33.2Retinotomy6

Retinotomy may be employed as the initial step in performing a retinectomy (see above), but stand-alone indications also exist.

•If the retina is shortened circumferentially, a radial cut can relieve the traction.

Pearl

The real strength of the traction force “tearing apart” a tissue is often not seen until the tissue is actually cut (see Fig. 33.3). When a tissue under traction or the tractional membrane itself is cut, the endpoints separate immediately and disproportionally.

•A small retinotomy is created if access to the subretinal space, to drain fluid or remove a membrane, is needed. The selection of the retinotomy site is described under Sect. 32.4.1 and the technique under Sect. 31.1.2. Whether the retinotomy needs lasering is discussed under Sect. 30.3.5.

33.3Chorioretinectomy7

The goal of this procedure is destroy the cells8 that are primarily responsible for postoperative PVR development. Chorioretinectomy is also able to liberate incarcerated but still attached retina that has developed full-thickness folds (see Fig. 33.4). The procedure is ideally done before proliferation occurs.

•Remove all vitreous in the area. Make sure that a PVD has been created.

–Anteriorly this may be impossible; remove the peripheral retina before applying the diathermy, especially if the procedure is done in the context of injury (see Sect. 63.7): it may be impossible to completely remove the vitreous in the vicinity of the planned chorioretinectomy.

•Reattach the retina so that you know precisely the final resting place of the retinal edge.

•Use the highest setting of the diathermy probe9 to create a contiguous line of treatment spots.

–The treatment may be applied over bare RPE adjacent to the retinal edge if a retinectomy has been performed or in the entire area of the retinal break (giant tear).

–Involve the retina as well if there is a deep IOFB impact site (see Fig. 63.9) or the retina is incarcerated and thus covers the RPE.

6The procedure discussed here is a stand-alone one, not as a precursor to retinectomy.

7For want of a more accurate term, this word describes the intentional destruction of both the retina and choroid. It is not truly an “ectomy” since the tissue is burned, not removed.

8Fibroblasts and the RPE.

9See above (Sect. 33.1) the caveats about diathermy use.