25.2.7 Epiretinal (Subhyaloidal) Materials

In addition to blocking the view of the underlying tissues, the settling on the retinal surface of blood or pus can be harmful, requiring its removal. If the posterior hyaloid is still attached, simply creating a PVD may be enough to lift the material off. If a PVD has already occurred, the technique is different.

25.2.7.1 Blood

If the blood is liquefied, the flute needle is the most natural choice for evacuation since its port is facing forward.38

•Keep the port over the pool of blood, lift your finger, and patiently wait for the blood to drain.

•If there is no drainage, you are probably too far away: carefully dip the tip into the blood itself.

Pearl

If the liquid blood does not evacuate even when the flute needle’s port is sunk into it, either the needle or the silicone tubing is blocked, or vitreous remains over the blood (no PVD).

•You can also try to “back-flush” the blood away from the retinal surface.

If the blood is clotted, it can be very adherent to the retina.39 It is best lifted using the probe, but keep in mind that a fragile retina may tear and/or the bleeding may recur. The clot is then cut with the probe, which temporarily mimics the appearance of a fresh bleeding.

25.2.7.2 Pus

In most cases, the pus is adherent to the retina. A vicious circle may be created: the surgeon does not remove the pus because he is afraid that he may injure the retina (see Chap. 45). However, the pus itself damages the retina, increasing the need for pus removal. It is true, though, that pus removal from a retina injured by the infection requires extra caution.40

•Use the probe only if it is held over the pus; never sink it into the purulent material.

– The chance of success with this technique is rather low.

38However, the probe can also be used. Typically it is sufficient to aspirate over the pool of blood. If the drainage is poor, immerse it in the blood, but be careful not to push the probe too deep into the blood so as to avoid injuring the yet-invisible retina.

39Commonly seen in diabetics.

40The technical difficulty is exacerbated by the presence of the cortical vitreous. The first step is thus the creation of a PVD.