Setons and serum IgG titers to silicone

To determine whether exposure to silicone shunts used in refractory glaucomas increases serum IgG binding to silicone and whether this response is associated with shunt-related complications or poor postoperative intraocular pressure control.

Sera from 12 patients (13 eyes) who had undergone placement of silicone seton implants were examined for IgG binding to silicone. Patients were monitored postoperatively for the occurrence of complications and intraocular pressure elevation (mean duration of exposure to silicone and follow-up, 25.1 months; range, 2.5-86 months).

The levels of serum IgG binding in 4 of the 12 patients were two standard deviations above the mean for control sera. No patients had titers greater than 46 arbitrary units (AU). Four patients developed shunt-related complications; the serum IgG binding to silicone for their sera ranged from 24 to 46 AU. Serum IgG binding values were not significantly correlated with poor postoperative intraocular pressure control, or with a history of autoimmune disease or malignancy, type of glaucoma, previous intraocular surgery, or chronic uveitis.

Although elevation of serum IgG binding to silicone may be noted in some patients receiving silicone seton shunts, individual levels do not seem to predict the development of shunt-related complications. Since the number of patients tested, the frequency of elevated IgG binding values, and the complication rate were relatively low in this study, it is difficult to exclude some clinicopathologic correlations. However, the results are in accord with previous studies of silicone ocular devices suggesting that clinically significant reactions to silicone ophthalmic implants must be rare events, and hence do not necessitate altering the use of these important devices.