Evaluations on the usefulness of viscous agents in anterior segment surgery. II. Effect on intraocular pressure and clearance from the anterior chamber.

Various viscous agents in anterior segment surgery were replaced with the aqueous humor of rabbit eyes. The effects of these agents on intraocular pressure (IOP) and their clearance from the anterior chamber were studied. Furthermore, the degradation of these agents in ocular and hepatic tissues was investigated. The IOP after the injection of a 1% solution of sodium hyaluronate with a molecular weight of 790 x 10(3) (Na-HA (790 x 10(3), 1%], fell to the normal level after 12 hours; however, after a 1% solution of sodium hyaluronate with a molecular weight of 2160 x 10(3) (Na-HA (2160 x 10(3), 1%], a 2% solution of methylcellulose with a molecular weight of 86 x 10(3) (MC (86 x 10(3), 2%] or a 30% solution of sodium chondroitin sulfate with a molecular weight of 30 x 10(3) (Na-Chs (30 x 10(3), 30%], the return of IOP to normal level required 24 hours. Six hours after the injection of MC (86 x 10(3), 2%), the IOP was significantly higher than those of other agents. Na-Chs (30 x 10(3), 30%) and Na-HA (790 x 10(3), 1%) were eliminated from the anterior chamber within 12 and 24 hours, respectively. Na-HA (2160 x 10(3), 1%) and MC (86 x 10(3), 2%) required 72 hours to be eliminated from the anterior chamber. The degradation of Na-HA was detected in extracts of the iris, corneo-scleral junction, and liver. The degradation of Na-Chs was also detected in the liver extract, but the degradation of MC was not detected. On the basis of these findings, and the results in our previous report with respect to the efficacy of the viscous agents, it is concluded that Na-HA is the best viscous agent to be used in anterior segment surgery.