V

C

SO

L

Fig. 35.3 Pressing silicone oil out of the AC with visco. (a) The cannula is advanced to the far end of the AC before visco is injected (blue arrows). (b) As the injection commences, the visco starts to push the bubble away from the AC periphery in either direction. The cannula is slowly withdrawn (black arrow), and with the visco continually entering the AC, the oil is exiting the AC (star). Make sure that the AC is split midway by the cannula: if it deviates to one side (let’s say toward 1 o’clock on this image), oil will remain trapped on the other side (toward 7 o’clock here). C cannula, SO silicone oil bubble, L cornea, V viscoelastic

•Keep the flute needle just behind the iris as you aspirate the air. Stop injecting oil once it reaches the iris plane. The eye will be soft but more oil will be added shortly (see above).

•Leave an air bubble in the AC to prevent oil prolapse.

35.4.5 With Silicone Oil in the Eye

35.4.5.1 General Considerations

•Silicone oil will not conform to a SB; a ring of fluid will be able to accumulate at the bottom of the central slope if a circumferential buckle has been used.

•A retina that is detaching under silicone oil will first push the oil anteriorly (see Fig. 35.4). If this is for some reason impossible,42 it will cause a tractional retinal tear and enter the subretinal space. The retinal break will have a characteristically oval shape (see Figs. 14.4 and 35.5).

•Very thin membranes often develop at the oil-retina interface. Usually they are detected only by the light reflected from their surface; their removal is not mandatory and is often risky.43

42The AC is already full of oil in the aphakic eye or the oil cannot find a passage to the AC in the (pseudo)phakic eye.

43The clinical experience is that the retina is more fragile if it has been in contact with the oil for extended periods.

Fig. 35.4 Silicone oil being pushed anteriorly. Unless the eye had the same appearance at the end of surgery – a highly unlikely scenario – the surgeon who sees this image during follow-up should immediately suspect that the retina has detached and is now pushing the silicone oil into the AC. The (in this case not exactly) 6 o’clock iridectomy is patent. Were it closed, it would still not be the cause but the consequence of the oil prolapse: as the pupil is stretched wide open, the iris stroma can be compressed

Fig. 35.5 Tractional retinal tears developing under silicone oil. The retina has remained reattached after the silicone oil has been removed. Two small, characteristically oval-shaped tractional tears have been found and surrounded by laser. The right-hand side of the image is blocked by the incoming air bubble

•If true proliferation occurs under normal oil, this will be inferiorly. The RD developing will progress slowly toward the posterior pole.

•Whether reoperation under silicone oil is necessary (see above) depends on many factors, mostly whether the macula is threatened. If reoperation is performed, remove the oil first, deal with the membranes, reattach the retina, and then reinject the silicone oil.