Free-radical formation may play a role in postoperative complications of
phacoemulsification (e.g., corneal endothelium damage from mechanical injury). The present experiments were aimed at investigating whether different molecular weight ranges (2000-2600, 2600-3200, or 3200-3800 kDa) of
hyaluronan may influence
free radical formation, corneal endothelium damage, and
inflammation parameters after
phacoemulsification in the rabbit eye. The viscoelastic substance was injected in the anterior chamber of rabbits' eyes before
phacoemulsification, at a 2.5% concentration. The formation of
free radicals was determined by adding
luminol to the irrigation media and measuring the chemoluminescence in eyes. The corneal endothelial damage was evaluated by measuring the corneal central thickness by pachimetry. The
inflammation parameters were measured by calculation in aqueous humor of peak levels of leukocytes and
prostaglandin E(2) (
PGE(2)) and evaluation in uveal tissue of
myeloperoxidase activity.
Hyaluronan decreased by about 58-60%
free-radical formation during
phacoemulsification, reduced by about 76-80% modifications in mean corneal thickness and by about 54-61% the
corneal endothelial cell loss in all molecular weight ranges used. No difference was found among various molecular weight ranges. The highest molecular weight range showed to be more potent than the lowest range for reduced number of
inflammation cells and level of
PGE(2) in aqueous humor. Thus,
hyaluronan reduces
free-radical formation, exerts protection on the corneal endothelium and exerts anti-
inflammation properties after
phacoemulsification in rabbits. The latter effect seems to depend on the molecular weight of the substance.