Pastor

Abstract

Silicone oil is a vitreous substitute used in complicated retinal detachments. The main indications for its use are moderate and advanced proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR) with tractional retinal detachment, and giant retinal tears (1). But the intraocular injection of silicone oil can cause various complications, such as wide variations in intraocular pressure (IOP) (hypotony and hypertony), band keratopathy and corneal alterations, emulsification, and preretinal reproliferation (PR) (1). Chemically, silicone oils are linear synthetic polymers (polydimethylsiloxanes) composed of different chains. Most silicone oils used worldwide have varying amounts of low-molecular-weight components (LMWC) due in part to the fact that there are no clear regulations on the degree of purification of the oils used in surgery (the so called medical grade). LMWC are believed to cause ocular toxicity (2-4). However, to the best of our knowledge, few studies have been conducted to prove this in humans. In the present retrospective study, we compared the use of a highly purified and a less purified silicone oil (both medical grade) in a consecutive series of 98 human eyes and assessed the incidence of complications in both groups. ABSTRACT: Purpose. To compare the ocular toxicity caused by the use of highly purified silicone oil to less purified silicone oil in humans. Methods. Fifty-six eyes received 2,000 centistokes (cs) purified silicone oil (group 1) and 42 eyes received 2,000 cs fractionated (highly purified) silicone oil (group 2) after pars plana vitrectormy. Follow-up ranged from 6 to 48 months. Results. Six months after injection, the following complications were found in groups 1 and 2, respectively: ocular hypotension (<13mmHg), 39.3% and 31%, sustained ocular hypertension (>23mmHg), 19.6% and 19%; acute hypertensive peaks (>30mmHg), 23.2% and 11.9%; corneal alterations, 19.6% and 14.3%; emulsification, 1.8% and 2.4%; silicone oil cloudiness, 28.6% and 0%; preretinal reproliferation, 14.3% and 4.8% and total or partial retinal reattachment, 78.6% and 90.5%. Conclusions. Highly purified silicone oil was better tolerated than the less purified oil and caused fewer complications. Poorly purified silicone oils should be avoided in clinical practice. (Eur J Ophthalmol 1998; 8: 179-83)