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39 AC Basics |
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39.3Anterior Synechia
Not all synechiae need to, or should, be released.
•If an acute synechia is encountered, use a blunt spatula (do not use visco – reduced control is the price you pay for the technical ease) to separate the iris from the cornea, and inject an air bubble to prevent readhesion. Such an air bubble is also effective if you want to prevent iris prolapse into a wound.
•If the iridocorneal adhesion is chronic but small, it is best to leave it alone to prevent bleeding or tissue damage such as tearing the iris root or Descemet’s membrane.
•If the iridocorneal adhesion is chronic and large, consider the risk-benefit ratio. If there is a strong argument8 in favor of releasing the iris, do not try blunt separation (see Sect. 13.2) but cut the iris (endodiathermy is recommended if vascularization is present or suspected). Some type of deep lamellar keratoplasty may become necessary, but this is outside the competence of the VR surgeon.
•If a true scar tissue is present, it should be left alone.
39.4Posterior Synechia9
The most common reason to release an iridocapsular or irido-IOL adhesion is to allow pupillary dilation (see Sect. 25.2.2.1), occasionally to treat iris bombans.
Pearl
The same general rule applies to posterior as to anterior synechiae: use blunt tools in fresh cases (when the cohesion within the tissues is greater than the adhesion between them) and sharp dissection in chronic cases (when the adhesion is stronger than the cohesion). Visco use is always questionable; its use is typically contraindicated behind the iris (see below).
Should the lens capsule need to be preserved in a phakic eye, miniscule amounts of visco can be injected between the iris and the lens capsule on either side of the adhesion. This creates enough space for the blade of a VR scissors to be inserted to severe the adhesion. If the iris itself has to be cut, every effort should be made to restore the diaphragm, both for anatomical and functional purposes (see Chap. 48).
39.5Material in the AC
Vitreous prolapse is discussed in Sects. 27.5.3 and 63.6, blood in Chap. 47, purulent material in Chap. 45, and IOFB in Sect. 63.7.1.
8Such as photophobia, poor cosmesis, ectopic pupil, the need to implant an iris-claw IOL.
9See Sect. 25.2.2.1 for more details.
Handling of Major Intraoperative |
40 |
Complications |
40.1Hemorrhage1
Of all possible intraoperative complications, this is the most threatening.
Pearl
Truly expulsive bleeding (ECH) does not occur during PPV since the operation is a closed-globe procedure. Nevertheless, a major bleeding can seriously interfere with the operation’s original goals and cause significant tissue damage. The surgeon may be forced to completely change his original plan or even abandon the operation.
Because the IOP during PPV is actually higher than it otherwise would be, major arterial bleeding from the choroid is extremely rare; should it occur, the IOP must instantly be elevated2 to stop the bleeding. See Table 40.1 for all other types of hemorrhage.
1The management of a chronic suprachoroidal hemorrhage is discussed in Chap. 60.
2If an open wound is present, the immediate goal is to close the wound (see Fig. 63.9), regardless of the type of surgery being performed. This is an event for which planning must be done beforehand (how to prevent it and how to react if it does occur), but when it occurs, the surgeon’s reaction must be automatic: no thinking, no strategizing, just instant wound closure.
© Springer International Publishing Switzerland 2016 |
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DOI 10.1007/978-3-319-19479-0_40
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40 Handling of Major Intraoperative Complications |
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Q&A
Q:Should patients on anticoagulation or antiplatelet treatment (aspirin, clopidogrel, warfarin) discontinue such treatment preoperatively?
A:There is no absolute answer to this crucial question. Intraoperative bleeding may occur even if the medication is continued; conversely, severe systemic complications may threaten if the medication is discontinued. It is probably safe to continue taking aspirin, but with the other medications it is best for the VR to (personally) consult the patient’s internist and make an individualized decision. (This is an advice for elective surgery; I will not delay an emergency operation [such as for endophthalmitis] if the patient is on, say, warfarin, but inform him about the risks of doing [and of not doing] the operation on an emergency basis.)
Table 40.1 Intraoperative hemorrhages and their management
Tissue |
|
Comment and managementa |
Uvea |
At sclerotomy siteb |
The bleeding is usually minimal, in which case no |
|
|
intervention is needed. If the bleeding is significant, use |
|
|
diathermy from the outside or from the insidec |
|
Iris |
Most commonly it accompanies the creation of an |
|
|
iridectomy.d To prevent it, the surgeon may consider using |
|
|
diathermy but only if neovascular tissue is suspected |
|
|
behind the iris. The bleeding is usually minimal, in which |
|
|
case no intervention is needed. If the bleeding is |
|
|
significant, use diathermy, but be aware that it is applied |
|
|
blindly since the actual source is almost never visible |
|
Ciliary body |
The bleeding can be profuse to the point that the exact |
|
|
location is impossible to find. Switch to air at high |
|
|
pressure, try to locate the source, and then diathermize it |
|
|
(see Sect. 32.5) |
|
Posterior choroid |
Most commonly an iatrogenic injury occurred; the bleeding |
|
|
is usually self-limiting,e in which case no intervention is |
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needed, other than subsequently removing the clot by |
|
|
aspiration or with forceps. If the bleeding is significant,f |
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use diathermy, but make sure that the power is high and |
|
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the duration long so that you do not cause an even more |
|
|
severe hemorrhage with the diathermy probe’s sharp tip. |
|
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The blood may have to be irrigated (see Sect. 36.3) |
Retina |
Major vessel |
It is virtually always the result of an iatrogenic injury. Switch |
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to air at high pressure and see if the bleeding stops. If not, |
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try to inject PFCL or silicone oil to contain it. Note that the |
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clot will need to be removed, which may restart the |
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bleeding. Light diathermy may be employed, but be |
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careful not to completely close the vessel, because this |
|
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would lead to a different set of postoperative complications |
|
Small vessel |
Most commonly seen in ILM peeling. The bleeding is |
|
|
usually minimal, in which case no intervention is needed |
|
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(see Sect. 32.1.3) |
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(continued) |
40.1 Hemorrhage |
381 |
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Table 40.1 (continued) |
|
Tissue |
Comment and managementa |
Proliferative/ Iris |
Occurs when an adherent membrane or lens capsule is |
neovascularg |
removed. If the bleeding is significant, use diathermy, |
|
but be aware that it is applied blindly since the bleeding |
|
vessel is not visible anteriorly |
Ciliary body |
The hemorrhage may originate in the ciliary body itself or |
|
in the newly formed membranes; in the latter case the |
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feeding vessel may lie very deep. The bleeding can be |
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profuse to the point that the exact location is impossible |
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to find (see above). Switch to air at high pressure, try to |
|
locate the source, and then diathermize it |
Retinal/intravitreal |
In general, large vessels bleed more readily and for |
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longer – but this does not mean that smaller vessels |
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cannot cause profuse bleeding. Especially in eyes with |
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anteriorly located proliferations, the feeding vessel may |
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be more anterior than the lesion itself. Switch to air at |
|
high pressure, try to locate the source, and then |
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diathermize it. Note that the clot will need to be |
|
removed, which may restart the bleeding |
Choroidal |
The surgeon plays Russian roulette when lifting the |
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membrane (see 32.4.2);h a profuse bleeding can occur if |
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the feeding vessel is patent. Administer anti-VEGF |
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therapy prior to the operation and raise the IOP during |
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surgery before taking the CNV; if there is a bleeding, |
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wait until it stops and then remove the clot, knowing that |
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the bleeding can restart. Diathermy is usually not |
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recommended at this location |
aIn each case, the surgeon should consider raising the IOP as the initial step; the more severe the bleeding, the more urgent it is and the higher the IOP should be. Raising the IOP using BSS is therefore not mentioned in the table.
bTypically it happens during reoperation, and neovascular proliferation underneath can be suspected.
cThe latter requires scleral indentation and cannot be performed if the eye is phakic.
dOccurs more commonly during PPV than if the iridectomy had been performed at the slit lamp. The reason for the higher incidence is the increased blood flow during surgery.
eTissue elasticity means that the bleeding is usually self-containing.
fEven then, it is a rather limited bleeding (not an “expulsive” type) since it will not be an arterial one.
gBleeding from an abnormal vessel is more dangerous because self-containment is much less likely.
hAs mentioned earlier, the patient must be fully aware of this risk before he agrees to the procedure; he must absolve the surgeon in advance since the bleeding does not occur due to any kind of negligence on the surgeon’s part.
The internist may suggest a switch from oral anticoagulants to intramuscular, short-acting heparin or enoxaparin. If in doubt, one can always check the INR level (should be lower than 3); the platelet count should be above 50,000.