Effects of Hyaluronan on Free-Radical Formation, Corneal Endothelium Damage, and Inflammation Parameters After Phacoemulsification in Rabbits

Abstract

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.

Alteration of free radical development by ophthalmic viscosurgical devices in phacoemulsification

“…Augustin and Dick 16 measured lipid peroxides as a marker of oxidative tissue damage in the aqueous humor after phacoemulsification in humans and demonstrated lipid peroxide levels were well correlated with the duration of the phacoemulsification. Camillieri et al 17 documented the effectiveness of hyaluronic acid in reducing free radical production and inflammatory parameters in the aqueous humor after phacoemulsification in rabbits. These results indicate that phacoemulsification is an oxidative insult to the corneal endothelium.…”

Corneal Endothelial Cell Damage by Free Radicals Associated With Ultrasound Oscillation

“…5 In addition, there are some recent studies that have shown that the phacoemulsification-associated endothelial injury may be caused by free radicals. [6][7][8][9] Based on these findings, it seems likely that the corneal endothelium can be damaged by free radicals during phacoemulsification because free radical species, hydroxyl radicals in particular, are highly reactive and can cause lethal injuries to cells. 10 The purpose of this study was to investigate the effects of free radicals on the corneal endothelium with special emphasis on histologic and immunohistochemical analyses after performing ultrasound oscillation in the anterior chambers of rabbit eyes.…”

Effect of Hypotonic 0.4% Hyaluronic Acid Drops in Dry Eye Patients: A Cross-Over Study

“…It has also been demonstrated that hyaluronate in anterior chamber during phacoemulsification has a pivotal role in controlling the inflammation, possibly on account of its preventing action in the formation of free radicals. 50 Based on the results of Cejková et al, 51 which point out that reactive nitrogen species are involved in the pathogenesis or selfpropagation of autoimmune dry eye syndrome, it could be hypothesized that hyaluronan might be the most appropriate molecule when the use of a lubricant is mandatory.…”