17.5 3D Viewing |
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The procedure may require one or two17 23 g ports; viewing is either through a separate port (endoscope; see Sect. 17.3) or via the IBO. The former option reduces the benefits of the procedure (minimal infrastructure and cost); the latter option makes the intervention technically difficult since the image is upside-down.
17.53D Viewing
This is a recently developed option in VR surgery. The surgeon, instead of looking into the microscope, watches the surgical field, wearing 3D glasses, as projected onto a large monitor; the image is captured by a 3D camera mounted on the microscope.
The system18 has certain advantages (such as allowing improved surgeon posture during PPV, permitting the fellow and all observers to see exactly the same image as the surgeon does, and decreased need for illumination power) and disadvantages (such as lower image resolution and the need of getting used to a completely new viewing option).
Pearl
The majority of PPVs will continue in the near future to be done using the traditional approach; however, the alternatives offer options that have distinct advantages for certain cases. As technology changes, the indication list of these currently rather limited approaches will undoubtedly grow. In an ideal world, the VR surgeon would have access to, and expertise with, all of the options listed above and select the most appropriate method in the particular case.
17Intrector and Retrector, respectively (Insight Instruments, Inc., Stuart, FL).
18TrueVision 3D Surgical, Santa Barbara, CA, USA.
Disinfection, Draping, and Perioperative |
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Medications |
18.1Disinfection and Draping
Proper disinfection is a crucial element in endophthalmitis prophylaxis in eyes undergoing PPV.
•Prior to the operation, the eye and its vicinity should be carefully inspected. Surgery should not proceed if there is discharge or the suspicion of a surface infection.
•The skin must thoroughly be cleansed with 10% povidone iodine,1 which must not be wiped off for at least 1 min. The area to be disinfected should be large (see Fig. 18.1).
Fig. 18.1 Preparing the patient for VR surgery. This patient is undergoing surgery in general anesthesia: the nostrils are tamponaded. The side for operation is marked and the skin disinfected with 10% povidone iodine in a large area
1 An antiseptic (bactericide) solution, which has safely been used even in persons who are presumed to have “iodine allergy”.
© Springer International Publishing Switzerland 2016 |
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F. Kuhn, Vitreoretinal Surgery: Strategies and Tactics,
DOI 10.1007/978-3-319-19479-0_18
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18 Disinfection, Draping, and Perioperative Medications |
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•The ocular surface must be irrigated with 5% povidone iodine, again left for at least 1 min, and then irrigated with saline/BSS to completely remove the disinfectant solution.
The drape may be placed by the nurse or the surgeon.
Pearl
Typically it is the nurse who drapes the patient. However, in case of an open globe injury, the surgeon should do the draping. Pressure on the globe must be avoided to prevent tissue prolapse or cause an ECH – risks the surgeon appreciates the most.
•The skin must be completely dry before the adhesive part of the drape is applied.2
•The drape must adhere to the skin “watertight.”
–Even if a small opening is present,3 the air can escape as the patient is exhaling. This introduces a potential risk factor for infection from the untreated skin and may cause condensation on the BIOM front lens (see Table 16.5).
–The opening also allows discharge from the nose to seep into the operative field; in general anesthesia, the nose should be tamponaded to prevent this (see Fig. 15.1). The nasal packings can also be soaked in 10% povidone iodine for added effect.
–Occasionally, the drape releases from the skin during the operation. The risk is not “only” endophthalmitis but also that the intravitreal instruments may stick to it. The surgeon does not necessarily notice this in the dark as he is
Fig. 18.2 The typical error in placing the adhesive drape. There is an opening (no sticking) on the nasal side inferiorly. This is easiest to avoid if the drape is pressed against the side of the nose first, only then onto the rest of the skin
2The adhesive does not work on wet surfaces.
3Which is usually on the nasal side, due to the surface incongruence caused by the nose (Fig. 18.2).
18.2 The Monocular Patient |
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focused on the retinal work. He simply feels resistance to the movement of his instruments (especially as he tries to penetrate deeper into the eye). Without realizing that there is resistance, he subconsciously applies greater penetration force. Once this overcomes the adhesion of the instrument to the drape, they suddenly separate, and the inertia carries the surgeon’s instrument forward, possibly hitting the retina.
•The eyelashes must be tucked underneath the adhesive drape.
–The lashes cannot be cleaned with the Betadine swipe as thoroughly as the skin.
The opening of the drape should be done by the surgeon; the risk of injuring the eyeball with the scissors is very small, but not zero. The scissors should be blunt, and once the initial “incision” has been made,4 the blades must be turned so that they can be advanced with the tips pointing slightly upward. Often no cutting is needed, only the pushing forward of the blades.
Pearl
If the drape is not opened properly, the transparent overhanging plastic can cover the top of the cannulas as the eyeball is rotated during the operation. The surgeon may not actually notice this, sensing only that he is unable to insert his instrument into the cannula. When the microscope light is turned on to find out why this is, he will have rotated the eyeball so that the drape does not cover the cannula anymore. The drape must be cut flush with the lid margin.
18.2The Monocular Patient
The monocular patient who wears a removable prosthetic eye requires special attention. In addition to preparing the eye undergoing surgery, precautions are in order for the prosthetic side:
•The prosthesis must be removed at least 1 day prior to the operation.
•The conjunctival sack must be disinfected.
•On the operating table, the prosthetic side must be treated as if this were the one undergoing the operation.
–10% povidone iodine on the periocular skin and in the conjunctival sac; this may be left behind, no need for irrigation.
•Ideally, the prosthetic side is draped over with a separate adhesive sheet.
4 When the tip of the scissors point downward, possibly facing the eyeball.