Abstract
The VR surgeon uses many hand instruments and numerous materials in his daily work, yet the characteristics of these instruments are almost never discussed in textbooks. Just as neglected are some basic guidelines about the use of the hand instruments, even though these have major implications regarding complication and success rates. The issues analyzed here range from the secure holding of a tool to actually operating them, and also a rationale for why a sharp instrument may be less risky to use than a blunt one or what may happen if the surgeon, under peer pressure, selects the inappropriate tool for a specific task.
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Notes
- 1.
Which is the ideal viewing tool (BIOM, see Chaps. 12 and 16) for all areas and tasks other than the finest manipulations on the central retina. Still, since the noncontact, high-resolution macula lens of the BIOM also allows maneuvers such as ILM peeling or separation of proliferative membranes, it is the individual surgeon’s personal choice whether he uses it or the contact lens.
- 2.
Magnifying (1.5×) contact lenses, with an even smaller field of view (30°), are also available.
- 3.
That is, restricting the field to the posterior pole.
- 4.
Certain vitrectomy machines allow the blades to be operated by the footpedal, without the need for the surgeon to squeeze the handle.
- 5.
Remember the obvious: you are manipulating the instrument extraocularly to achieve an effect intraocularly. You have visual feedback of the latter but only tactile feedback of the former. The less you need to manipulate the extraocular part, the better.
- 6.
A careful chef will have a smaller chance of cutting his fingers when slicing meat with a sharp than with a blunt knife: the blunt blade requires more force to be effective, thereby reducing the chef’s control over the process.
- 7.
The design of the handle (“squeezability”) makes a huge difference in how user-friendly they are.
- 8.
The default position of the tool is “open”: it is the surgeon’s action that forces the tool to “close.” There are also tools that work with “reverse” action: the default option is the “closed” position.
- 9.
They move simultaneously, along mirrored paths and equal distances – even if one blade is longer than the other.
- 10.
To compensate for this, the surgeon should squeeze the handle before engaging the membrane. The aperture (distance between the blades/jaws) must be slightly larger than the tissue to be attacked. This is, however, still not an ideal solution since the fingers must now simultaneously fulfill two functions: squeezing the handle plus positioning the jaws on the target tissue. If the ILM forceps has a default opening of 1 mm, squeeze it by ~80% before any grabbing attempt.
- 11.
Think about a driver and the resistance of the gas pedal in the car. On a long trip, it is great to have a pedal with high resistance because the driver can simply rest his foot on it. When doing a fine maneuver such as starting to move a stopped car, however, and this is what describes the forceps analogy, the driver wants minimal resistance so that the car transitions from “stop to go” smoothly and the engine neither dies nor revs.
- 12.
The alternative is a reusable handle that allows the rotation of the jaws/blades into the ideal position before the handle is actuated (see Sect. 44.2.2).
- 13.
Unfortunately the so-called “crocodile” (serrated) forceps has the serration edged perpendicularly to its axis; this limits the surface of contact to be small in most cases and may allow the subretinal membranes that are directly underneath the retinotomy or in close proximity to it to slip from the forceps jaws (see Fig. 13.6).
- 14.
End-gripping means that the jaws close only at their very tip.
- 15.
The disadvantage is that the surgeon has to pay attention to keeping the handle squeezed – which also interferes to some extent with how delicate his finger movements can be.
- 16.
The blade is perpendicular to the axis, is a linear continuation of it, or is in-between. The first two have straight blades. The vertical may also be asymmetrical: the lower blade is longer than the proximal one.
- 17.
Although occasionally the tip of the vertical blades must be turned toward the retina to pick up a membrane, which is then dragged toward the surgeon. Keep in mind that this is a risky maneuver.
- 18.
In other words, the blade will not cut the membrane while it is manipulating it.
- 19.
The cannula in MIVS limits blade length, unless retractable blades of memory material are used.
- 20.
This is equally true for forceps use.
- 21.
Remember the carpenter’s primary rule: measure twice before cutting (once). Cutting is a one-way street.
- 22.
Unless the membrane moves during cutting, which adds to the complexity of the maneuver.
- 23.
Which is by far my preferred type.
- 24.
More details about flute needle use are provided under Sects. 25.2.7 and 31.1.2. Always use a back-flush type, which also allows blowing away materials and offers an escape route when you catch retina with the tip (see below). The flute needle is known in many countries as Charles needle, after its inventor. The name is misleading: it is not just a needle but an entire device. The German name (Staubsauger, vacuum cleaner) is more accurate and certainly more descriptive.
- 25.
Such as blood (in a previously vitrectomized eye), BSS (during A-F X), PFCL.
- 26.
High myopia, diabetes etc.
- 27.
That is, the drainage is slower.
- 28.
As a historical note, in the “pre-TA” era the soft-tipped cannula has been used to determine whether the posterior hyaloid is still on the retinal surface (“fish strike” phenomenon).
- 29.
In lieu of a bent-tip MVR blade, this is my favorite tool to start lifting fine, often even thick, epiretinal membranes and identifying invisible ones in proliferative diseases such as PVR or PDR.
- 30.
Other potential uses outside the vitreous cavity (e.g., see Fig. 13.3) are not listed here.
- 31.
Barely visible; this is why the barb is never prepared by hitting (bumping) a metal surface with it.
- 32.
Which is the preferred option, to avoid the difficulty of pushing the tool past the cannula’s valve.
- 33.
As discussed under Sect. 32.2.2.5., the “centrifugal” peeling of an EMP appears similar, but, due to the different characteristics of the tools used (forceps vs spatula), the effect is also different. The forceps, if used to grab the membrane in its central part, causes traction over large area; the spatula has a much more local effect. By moving it sideways and in both directions, the surgeon separates the membrane from the retina in a controlled fashion.
- 34.
Similar to what was described above with the vertical scissors (see Sect. 13.2.1.4).
- 35.
The surgeon must always make sure that the IOFB is completely freed of all its VR connections before being approached with the intraocular magnet.
- 36.
In fact, because the material is not only viscous but also elastic, the flow does not stop immediately.
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Kuhn, F. (2016). Instruments, Tools, and Their Use. In: Vitreoretinal Surgery: Strategies and Tactics. Springer, Cham. https://doi.org/10.1007/978-3-319-19479-0_13
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