Protective efficacy of sodium hyaluronate on the corneal endothelium against the damage induced by sonication.

The protective efficacy of sodium hyaluronate (Na-HA) on the corneal endothelium against the damage induced by sonication was investigated using enucleated rabbit eyes and Na-HA fluorescence labeled with 5-aminofluorescein (FA-HA). The anterior chamber was reformed by injecting a 1% solution of FA-HA, and then sonication, irrigation and aspiration were performed in the anterior chamber using a phaco-needle attached to phacoemulsification and aspiration (PEA) equipment. The protective efficacy was evaluated by the area of damaged corneal endothelium. When the anterior chamber was reformed by the solution of FA-HA with a molecular weight of 2010 x 10(3) (FA-HA (2010 x 10(3) group), most of the FA-HA was eliminated within 20 seconds after starting the irrigation and aspiration, and the area of damaged endothelium was the same with the case when the FA-HA was not pre-injected (Control group). On the other hand, when the anterior chamber was reformed by the solution of FA-HA with a molecular weight of 1130 x 10(3) (FA-HA (1130 x 10(3) group), the FA-HA was gradually eliminated after mixing with an irrigating solution, and the area of damaged endothelium was significantly smaller than those of the Control and FA-HA (2010 x 10(3)) groups. These results suggest that the corneal endothelial damage induced by PEA can be avoided by pre-injecting a viscoelastic material which can remain in the anterior chamber during PEA.