Recent experiences and indications for Perfluorocarbon Perfused Vitrectomy (PCPV)

Hugo Quiroz-Mercado (Mexico City)

These are relevant observations about the technique perfluorocarbon perfused vitrectomy
(PCPV). Those are based after performed experiments in normal eyes of rabbits and pigs; in
human eyes harboring miscellaneous pathologies: TRD secondary to PDR, rhegmatogenous RD with and without PVR, macular hole, giant retinal tear, tumors, IOFB, silicon oil removal, vitreous biopsy, and serous retinal detachment. In all cases surgery is started with PCL it is not need to start with BSS. As soon as infusion of PCL starts bubbles in the vitreous cavity are observed. In some cases this bubbles disappear as soon as vitrectomy is started with vitrectomy probe. In some cases these bubbles remain but never interfere with visualization. The presence of bubbles has been related with small infusion canulas. We frequently use medium size or large canulas when using PCPV. Bubbles may be formed if vitreous body is around or producing a “semi-plug” at the tip of the canula. This is an observation that has to be confirmed. The exact cause of PCL bubbles has not been determined but in some cases these almost never appear. Vitreous always floats in PCL and never mixes with it. That implies that vitrectomy is performed in the anterior part of vitreous cavity when the eye has a pre-operative PVD. It has to be performed as when vitreous base is removed (360 degrees). If there is not a pre-operative PVD, we start the procedure by a central vitrectomy until a single big PCL bubble is formed that allows a nice visualization of the vitreous cavity. There after always a separation of the posterior hyaloid is produced. This maneuver is described in the following paragraphs. Separation of the posterior hyaloid when the vitreous has not membranes and or posterior hyaloid is not thickened. We have done this maneuver in rhegmatogenous RD, macular hole and hemangiomas of young patients. The purpose of induction of a PVD is to allow entrance of PCL into retrohyaloidal space to make a centrifugal separation of the vitreous. Ocutome probe is positioned in front of the optic disc and suction is increased gradually starting with 150 mmHg until a nice separation is observed. Visualization of this maneuver has been enhanced by the use of tripan blue, kenalog or fluorescein. In a few cases of young patients small islands of vitreous body may remain; these are easily visualized because PCL is immiscible with vitreous. Separation of a thickened posterior hyaloid or in a vitreous that has membranes like in PDR, is easy. After a core vitrectomy and formation of a single bubble the next step is always the separation of fibrotic and frequently distorted Wise ring that can be identified in front or adjacent to the optic disc. This maneuver will allows entrance of PCL into the posterior hyaloid. The posterior hyaloid is visualized nicely and can be removed with vitrectomy probe. At the same time epicenters can be observed; these can be shaved and aspirated with vitrectomy without the need of scissors for segmentation. When a very thick membrane is present scissors may be used for segmentation. If a iatrogenic retinotomy is performed PCL never enters the subretinal space because this is locked by gravitational forces of the PCL bubble. If in cases like PDR the vitrectomy is
started at the periphery outside of arcades when membranes from the posterior pole has not been separated, an accidental
retinotomy may allows entrance of PCL into the posterior hyaloid. For this reason we always recommend that separation of
posterior hyaloid and membranes in diabetic patients as well as in other ischemic pathologies should be started at the
posterior pole.
In eyes with retinal detachment, even in diabetic eyes with fibrotic membranes retinal elasticity allows reattachment and
safe dissection and gentile pooling of the membrane. Continuous infusion of PCL maintains a stable retina during
membrane dissection. In eyes with severe PVR retina is not elastic and PCL may enter into the subretinal space. We have
seen that PCL goes subretinal where the retina is taut but not where the retina is elastic: in such cases we have performed
extensive retinotomy of taut retina with vitrector leaving the retina that is attached with PCL in all cases laser under PCL
was used on the borders of the attached retina.
The way vitreous is removed:
By infusion of BSS in the vitreous body, it may hydrate and vitrectomy probe aspirated hydrated vitreous and BSS. By infusion
of PCL vitreous may be compressed and dehydrated. If vitrectomy prove is placed into former gel it could be aspirated
faster by regular aspiration (150 mmHg) and not a very fast cutting rate (600) using an Alcon Accurus machine. High aspiration
will never aspirates the retina at the time of vitreous removal.
It has been observed in clinical situations that vitrectomy time is less in PCPV that in vitrectomy using BSS, also that the
amount of fluid is less. In PCPV is rare to use more than 60 cc of fluid. Explanation of this phenomenon is not clear.
Intraocular pressure is driven by the altitude of PCL bottle but it can be connected to the Accurus vitrector as it is done
with BSS. It is easy to observe optic nerve pallor if it is maintain high (more than 1 meter above patient’s head).
Complications: The most common complication in eyes with active bleeding vessels is blurring of visualization through the pupil due to an interface of blood between the PCL bubble and pupil (posterior capsule). It can be solved just by taken the vitrector probe out of the eye to allow blood to exit through the sclerotomy. If this maneuver does not clears the view, PCL infusion should be changed to a BSS that always cleans blood form the top of the bubble. Infusion then can be switch back to PCL. In severe cases of PVR but less frequent in PDR when the retina is taut, retina will not reattach by gravitational forces of PCL and may enter the subretinal space through a previous tear or a new one. If in such cases or in other cases by accident enters PCL into the subretinal space, infusion is changed either to BSS or air to remove PCL with a regular Charles flute or translocation canula. We have not done studies on the effect on rapid changes in IOP after continuous infusion of PCL with high pressure and the switch to air or BSS in less pressure but we recommend that it should be done gradual in order to avoid potential damage to choroidal and retinal circulation. If at the end of the surgery PCL infusion is changed to air rather than BSS small intravitreal bubbles may remain. BSS infusion may wash them out easily. Since the most toxic effect of PCL is related to gravitational forces the may not be harmful; on the contrary in ischemic ayes, they may provide small amount of oxygen from general circulation (personal speculation).
Other less frequent indications are: vitreous biopsy, endoftalmitis, removal of tumors, treatment of massive choroidal detachments, vitrectomy in serous retinal detachment and stage 4 ROP, IOFB removal, silicon oil removal with and without subretinal silicon oil. The use of 25g can save the amount of PCL used (we have done more than 10 cases) and may fasten vitrectomy time although may be more difficult to separate posterior hyaloid by aspiration. PCL are less viscous than BSS allowing rapid flow in a less diameter tubing system. Oxygenation is a great potential advantage that has not been proven in clinical conditions but deserves extensive study, mostly for eyes with ischemic conditions lake vascular vein occlusions and diabetic retinopathy.

Back