Comparison of the performance and safety of 2 ophthalmic viscosurgical devices in cataract surgery.

PURPOSE: To compare the clinical performance and safety of 2 ophthalmic viscosurgical devices (OVDs)-Twinvisc (OVD 1) and Duovisc (OVD 2)-in cataract surgery. SETTING: European multicenter study. DESIGN: Prospective randomized controlled study. METHODS: Patients with cataract had phacoemulsification and intraocular lens implantation in 1 eye. They were randomly assigned to receive OVD 1 or OVD 2. Preoperative and postoperative examinations over 3 months included mean intraocular pressure (IOP), incidence of IOP peaks (≥30 mm Hg and ≥24 mm Hg), endothelial cell count (ECC), corneal thickness, and intraocular inflammation. A subjective evaluation of the OVDs was performed. RESULTS: The study comprised 220 patients. The incidence of IOP peaks and the mean IOP were not statistically significantly different between the 2 groups at any of the follow-up visits. At 6 hours, the incidence of IOP spikes 30 mm Hg or higher was 6.5% and 7.2% in the OVD 1 and the OVD 2 groups, respectively (P = .846). For the IOP spikes 24 mm Hg or higher, the incidence was 16.8% and 25.2%, respectively (P = .128). Three months postoperatively there was no statistically significant difference in ECC and pachymetry between the 2 groups. Mild inflammation was noticed up to 7 days postoperatively after which it resolved in both groups. Subjectively, the OVD 2 was easier to use, whereas the OVD 1 had better cohesive and dispersive properties. CONCLUSIONS: Both OVDs have similar performance and safety profiles in phacoemulsification cataract surgery. No clinically relevant differences were found between the 2 devices regarding transient IOP spikes, mean IOP, corneal endothelium injury, or inflammation.

The role of amino acids in corneal stromal healing: a method for evaluating cellular density and extracellular matrix distribution.

PURPOSE: To evaluate how amino acid supplementation influences the response of corneal stromal keratocytes and other components of the corneal stroma. METHODS: We compared two groups of patients undergoing cataract surgery. Each group included 20 eyes of 20 patients. Patients in Group 1 were treated with amino acids for 15 days before surgery, and patients in Group 2 did not receive amino acids (control). To evaluate differences and change in corneal stroma, we analyzed all of the operated corneas with confocal microscopy. The confocal images were then analyzed with a new method for measurement of corneal structure based on fractal dimension calculation. This led to a numerical value, D index (fractal surface dimension), an objective measurement of corneal stromal characteristics. This index is related to three factors: keratocyte density, stromal distribution pattern, and intercellular matrix structure. RESULTS: Patients in the preoperative amino acid group showed higher keratocyte density values than those in the control group. We observed differences in cell distribution patterns and intercellular matrix structures between groups. Amino acid-treated patients had a corneal stroma with a D index value 10% higher than control group patients. CONCLUSIONS: We hypothesized that preoperative oral supplements with amino acids may change the corneal stroma structure by increasing keratocyte density and modifying the intercellular matrix. A new method for the measurement of these changes was applied, which provides quantification of the stromal structure complexity with a single numerical value.

Use of amino acids in refractive surgery.

PURPOSE: To assess the influence of amino acid supplements on corneal fibroblast activity during corneal healing in patients with chronic ulcers, as well as after refractive surgery when delayed re-epithelialization had been observed in the fellow eye. METHODS: Studies were conducted in vitro on eye bank eyes, and in vivo. In vitro cultures of rabbit corneal fibroblasts were enriched with progressively higher concentrations of amino acids. The human eye bank cornea study involved corneal epithelium removal, with corneas kept for 7 days in standard storage medium, either simple or enriched with amino acids. Clinical studies included treatment of two groups: Group 1 included six eyes of six patients with chronic epithelial defects, resistant to usual treatment; Group 2 included 21 eyes of 21 patients with delayed re-epithelialization after PRK in the first eye (12 +/- 3 days). Group 1 was treated for 1 month, and Group 2 received treatment preoperatively and postoperatively after surgery in the fellow eye until re-epithelialization was achieved. All patients received 13 amino acids and Vitamin C in three tablets, three times per day. RESULTS: Cultures of rabbit corneal fibroblasts showed that progressively increasing amino acid supplements led to an increase in the percentage of fibroblasts. De-epithelialized human eye bank corneas incubated with amino acids showed thicker and better organized re-epithelialization when compared to corneas incubated in simple standard storage media. In the clinical study, five eyes in Group 1 showed substantial improvement, one eyes remained unchanged. All eyes in Group 2 showed complete re-epithelialization within 60 hours after surgery. CONCLUSION: Results suggest improvement of re-epithelialization when an increase of serum and tear film amino acids is obtained through oral administration.