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The blood, whether of AMD,1 trauma, or other etiology, causes severe damage to the photoreceptors2 and does it very early; the thicker3 the blood, the more the damage. Several options are available, including observation – justified if the blood is long standing, the hemorrhage is thin and small, or the visual acuity had been very poor prior to the bleeding.
36.1The Nonsurgical Approach: Intravitreal Gas and tPA
The goal is to push the liquefied blood from under the fovea.
•Inject up to 100 μg tPA into the vitreous cavity.
•Inject up to 0.3 ml of pure perfluoropropane (C3F8) gas into the vitreous cavity.
•Position the patient4 for 3 days.
36.2Removal of the Clot In Toto
Technically, the blood clot is not as difficult to remove as it may appear, nor does it require as large a retinotomy as the clot’s dimensions would suggest. It is usually possible to remove the elastic clot in one piece and through a rather small retinotomy.
1Anti-VEGF therapy must also be employed, irrespective of how the bleeding is treated.
2Eventually the blood may turn into a scar.
3“Thick” is usually defined as over 500 μ.
4Facedown is the typical recommendation, but it makes more sense to ask the patient to be erect so that the blood settles inferiorly.
© Springer International Publishing Switzerland 2016 |
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F. Kuhn, Vitreoretinal Surgery: Strategies and Tactics,
DOI 10.1007/978-3-319-19479-0_36
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•Complete the vitrectomy (especially, create a PVD).
•Use diathermy to create a small retinotomy at a convenient location.5
–The retinotomy should be far away from the major vessels in the area.
–The retinotomy should be placed right above the clot in MIVS.6
–If the clot proves to be too large, the retinotomy will stretch somewhat.
•Use a small, blunt, angled,7 cannula or a soft-tipped flute needle to inject a little BSS over, and if possible under, the clot to separate it from the neuroretina above and the RPE beneath.8
–The injection should be very slow and at low pressure.
–It is difficult for the surgeon to precisely control both the position of the cannula’s tip and the attributes of the injection. It is best to use a tool (see below, Sect. 36.4) that allows the nurse to inject the fluid while the surgeon monitors the tip of the cannula.
•Grab the clot with forceps and slowly retrieve it. Pausing during retrieval may help the retina to slide backward, separating from the clot.
•Gently irrigate the subretinal space with BSS.
•Perform a F-A-X and exchange the air for gas (see Fig. 35.1).
The main problem with this approach is that large areas of the RPE may be inadvertently removed, making the prognosis unpredictable. The patient must understand in advance this risk and that its occurrence is not due to surgeon error (counseling; see Chap. 5).
Pearl
The patient must always be told in advance that the functional outcome after removal (or displacement) of submacular bleeding is questionable, but that in most cases it still may be the best hope for improvement.
A very large clot requires a large peripheral retinotomy for removal; this typically occurs in trauma (see Fig. 36.1), although occasionally AMD is the etiology.
5Typically, superotemporal to the macula.
6May be at the edge of the clot in 20 g PPV if a subretinal forceps (see Sect. 32.4.1) is available.
7A tip bent at ~30°. Not angling the cannula means the jet stream hits the RPE or the clot, rather than creating a cleavage above or underneath the clot. The soft-tipped cannula is obviously unable to produce such an angle, but having a cannula in the sclera in MIVS limits the surgeon’s choices regarding instrumentation: the cannula must be smaller than the g used and the angled distal tip must be very short.
8Sub-RPE clots should not be removed, only displaced; OCT helps distinguishing between the two.
36.3 Submacular Irrigation |
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Fig. 36.1 Removal of a large clot through a large peripheral retinotomy. In this severely traumatized eye, the huge clot (the blood did not liquefy in 20 days) is removed after a 90° peripheral retinotomy was created. The retina is folded back, and the 20 g vitrectomy probe is used to aspirate the clot, lift it into the vitreous cavity, and then cut and remove it
36.3Submacular Irrigation9
•Complete the vitrectomy (especially, create a PVD).
•Use diathermy to create a small retinotomy at a convenient location (see above).
•Use a bent cannula (see above) or a special flute needle (see Fig. 36.2) with injection capability, to gently inject BSS under the macula.
–Use of the cannula means the blood is flushed into the vitreous cavity; you need to remove the cannula and evacuate the intravitreal blood, then repeat the process a few times.
–Use of the special flute needle means that the nurse must inject the BSS to irrigate the subretinal space, which requires skills, attention, and dedication (see Chap. 6). The process will have to be repeated a few times.
If there is residual blood under the fovea, PFCL may be injected to try to push the blood out of the epicenter toward the retinotomy, similar to the technique employed during the removal of subretinal fluid in RD surgery (see
Sect. 31.1.2).
9 The same technique applies for subretinal fluid of other types.
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Fig. 36.2 Simplified irrigation of the subretinal space. This flute needle is special because it allows attaching a syringe to it. When the surgeon’s index finger blocks the silicone chamber’s opening and the plunger is activated, fluid is injected through the flute needle, which has a soft tip. Not shown here: when the plunger is not pushed and the surgeon’s finger is off the silicone chamber’s opening, the device reverts back to a normal flute needle, draining the bloody fluid from the eye. The advantage of this method is that it does not require multiple instrument exchanges to achieve the evacuation of the material. (This idea originates with one of my nurses, Barbara Slupcznska-Sowka)
36.4The Minimalistic Surgical Approach
•Complete the vitrectomy (especially, create a PVD).
•Using a 41 g microcannula, inject up to 50 μg tPA into the area of the clot.
–One option is to wait up to an hour for the clot to liquefy, then irrigate the blood (see above), followed by a F-A-X and exchange of the air for gas. Prone positioning is usually recommended.
–Another option is to forego the irrigation, and after the tPA injection, immediately perform a F-A-X and then exchange the air for gas.