(1)
St. Johns, FL, USA
(2)
Helen Keller Foundation for Research and Education, International Society of Ocular Trauma, Birmingham, AL, USA
(3)
Consultant and Vitreoretinal Surgeon, Milos Eye Hospital, Belgrade, Serbia
(4)
Consultant and Vitreoretinal Surgeon, Zagórskiego Eye Hospital, Cracow, Poland
33.1 Retinectomy
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?
A
There 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.
Q&A
Q
How do you determine the necessary length of the retinotomy?
A
It 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 bleed. To minimize this risk, use low aspiration/flow, and turn the probe toward the peripheral retina, not toward the central retina.
Once the retinotomy is complete, use the probe to remove the entire peripheral retina.4 Scleral indentation may be needed to accomplish this task.
The detached, nonfunctioning peripheral retina is a major producer of VEGF.
Reattach the retina under air or PFCL (see Fig. 33.1 and Table 35.2).
360° retinectomy allows examination of the back surface of the retina and removal of any membrane that may have grown on it, including the ring proliferation (see Sect. 32.3.1.5).
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