Sodium hyaluronate (Healon) in closed vitrectomy.

Healon was implanted into the vitreous cavity of 33 eyes at the conclusion of pars plana vitrectomy. In aphakic eyes, Healon diffused rapidly into the anterior chamber, reducing the length of effective tamponade posteriorly and causing marked elevations of intraocular pressure. In phakic diabetic eyes, Healon appeared to trap hemorrhage mechanically from bleeding fibrovascular stumps posteriorly. It may therefore reduce the risk of opacifying vitreous hemorrhage after vitrectomy in phakic eyes with active neovascularization.