Klaus Lucke (Bremen, Germany)

The use of silicone oil for complex retinal detachments was developed primarily in Europe in the 70’s and 80’s. While there is widespread agreement on its advantages, to this day the mechanisms of action are not entirely understood and remain in part hypothetical. Recent developments such as the use of heavy oils, however, have shed some light on the mechanisms behind the beneficial effects of silicone oil and confirmed some old hypotheses:

a) First and foremost, by virtue of its high surface tension, it acts as a very effective tamponade by resisting protrusion underneath the retina, even though the surface tension is significantly less than air or gas. It rather presses on the edges of large defects and thereby reattaches them. By this it allows the treatment of giant tears and other large defects. This also empowers the surgeon to create large retinectomies if necessary for traction relief without much concern that the defects thus created could cause a long term problem.

b) Reducing the amount of fluid overlying a retinal defect results in diminished fluid currents elevating the retina.

c) By filling much of the intravitreal space it blocks the movement of cells and biochemical mediators of inflammation (”no space – no cells“). Thereby it reduces the development of PVR and in cases such as fresh giant tears it actually effectively prevents the development of PVR.

d) Finally it is thought that the presence of an inert bubble in the intravitreal space can modify the growth characteristics of membranes growing on the retina. Silicone oil forces them to grow more parallel to the retinal surface so that they exert less anterior-posterior traction on the retina allowing the retina to stay attached longer.

These considerations help understand why silicone oil has proven to be effective in treating complex retinal detachments with large defects and/or PVR.