Dilation of Schlemm's canal in viscocanalostomy: comparison of 2 viscoelastic substances

To study the injection of viscoelastic material into Schlemm's canal adjacent to and 6.0 mm from the scleral flap during viscocanalostomy in an autopsy eye model.

Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

Viscocanalostomy was performed in 8 postmortem human globes. Sodium hyaluronate (Healon GV or Healon5) was injected into 1 side of Schlemm's canal, with the other side serving as a control in some eyes. The eyes were prepared for light microscopic analysis, and serial pathologic sections were taken adjacent to the flap and 6.0 mm circumferentially from the flap. The area of Schlemm's canal was calculated and compared using t tests.

Injecting viscoelastic material enlarged the area of Schlemm's canal adjacent to and 6.0 mm from the flap significantly more than not injecting viscoelastic material. While there was no difference between the viscoelastic materials in dilating Schlemm's canal at the flap, with Healon5 there was a small but statistically significantly greater dilation 6.0 mm from the flap. No full-thickness breaks in the trabecular meshwork were noted adjacent to or 6.0 mm from the flap.

Injecting viscoelastic material significantly increased the cross-sectional area of Schlemm's canal and may play a role in the success of viscocanalostomy. Further study is needed to elucidate the mechanism of this procedure.