Corneal Wound Healing in New Zealand White Rabbits Following Anterior Keratectomy and Treatment with Moxifloxacin Ophthalmic Solution 0.5% or Gatifloxacin Ophthalmic Solution 0.3%

Effects of Fluoroquinolone-Based Antibacterial Ophthalmic Solutions on Corneal Wound Healing

PURPOSE

To evaluate the effects of fluoroquinolone-based antibacterial ophthalmic solutions on cell proliferation in vitro and corneal wound healing in vivo.

METHODS

Staten's Serum institute rabbit corneal cells were exposed to phosphate-buffered saline, 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin, for 2 min, following which the cells were incubated without the drug. The cell viability was evaluated after 24 or 72 h of incubation. Rabbit corneal epithelial abrasion models created using n-heptanol were instilled with saline or fluoroquinolone-based solutions 7 times at 30-min intervals, following which corneal epithelial wound healing was evaluated from 30 min to 48 h by the measurement of electrical corneal resistance (CR) ratios.

RESULTS

The cell viability decreased over time; the lowest values were observed with 1.5% levofloxacin. Significant differences in cell viability were observed among the 4 solutions at 72 h (P<0.05); the cell viabilities of 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin were 21.6%, 97.9%, 39.1%, and 67.5%, respectively. The electrical CR ratios at 48 h after instillation were 103.8% (saline), 78.2% (1.5% levofloxacin), 105.0% (0.5% levofloxacin), 74.9% (0.5% moxifloxacin), and 87.7% (0.3% gatifloxacin); the difference was significant between 1.5% levofloxacin or 0.5% moxifloxacin and saline (P<0.05).

CONCLUSIONS

The cytotoxicities of 1.5% and 0.5% levofloxacin, 0.5% moxifloxacin, and 0.3% gatifloxacin were different, and 1.5% levofloxacin and 0.5% moxifloxacin resulted in delayed corneal wound healing. The results suggest that 1.5% levofloxacin exerts the greatest influence on corneal wound healing.

Novel collagen membranes for the reconstruction of the corneal surface

No standardized biomaterial exists for the surgical treatment of persistent corneal erosions and ulcerations. We analyzed the suitability and biocompatibility of defined noncross-linked and UV/riboflavin cross-linked equine type I collagen membranes for the reconstruction of the corneal surface. Isolated human oral mucosa epithelial cells, a cell type in clinical use for the treatment of ocular surface diseases, were subcultivated on both types of membranes and examined concerning cell adhesion, proliferation, and differentiation. Biocompatibility was evaluated following superficial and intrastromal corneal transplantation in New Zealand white rabbits. In cell cultures all collagen membranes supported adhesion of oral mucosa epithelial cells leading to the formation of multilayered epithelial cell sheets. After intrastromal corneal implantation clinical signs of degradation were seen in all variants of collagen membranes, which was fastest in noncross-linked variants. The histological and ultrastructural level invasion of keratocytes and production of new collagen fibers inside the collagen membranes could be detected in noncross-linked variants. After superficial corneal implantation covering of the membranes by corneal epithelium over time was visible. Ultrastructural analysis showed a slower rate of degradation and less invading keratocytes in cross-linked variants compared with noncross-linked collagen membranes. Cross-linked and noncross-linked variants of the collagen membrane proofed to be suitable to serve as a carrier for epithelial stem cells in vitro and showed a high biocompatibility in vivo. These results indicate that the tested collagen membranes might be suitable for the reconstruction of the corneal surface in patients with nonhealing ulcerations. Whether membranes with faster or slower degradation properties are preferable for the treatment of persistent corneal ulcerations might depend on the underlying corneal pathology and the degree of concomitant inflammation.

Comparison of the effects of fourth-generation fluoroquinolones on epithelial healing after photorefractive keratectomy

PURPOSE

To compare the effects of fluoroquinolones gatifloxacin and moxifloxacin used for antimicrobial prophylaxis after photorefractive keratectomy (PRK) on epithelial healing.

METHODS

Forty-four patients randomly received the prophylactic antibiotics gatifloxacin (Gatiflo; 0.3% gatifloxacin ophthalmic solution, Handok, Chungbuk, Korea, no preservative) in 1 eye and moxifloxacin (Vigamox; 0.5% moxifloxacin hydrochloride ophthalmic solution, Alcon Laboratories, Inc, Fort Worth, TX, no preservative) in the fellow eye after PRK. Corneal epithelium was circumferentially removed along a 7-mm zone mark. After PRK, all patients used topical antibiotics 4 times a day until the epithelium healed completely. Starting from postoperative day 1, epithelial healing times and defect sizes were recorded by slit-lamp examination and anterior segment photography. Postoperative pain and discomfort induced by the eyedrops were recorded. Additionally, therapeutic contact lenses were cultured to assess the antibacterial efficacy of fluoroquinolones.

RESULTS

The mean epithelial healing times after PRK were similar for the 2 groups: 2.97 ± 0.41 days for gatifloxacin and 2.95 ± 0.48 days for moxifloxacin (P = 0.81). There was no statistically significant difference in mean defect size on each postoperative day between the treatment groups. There was no difference in postoperative pain and discomfort. No statistically significant differences were observed between eyes treated with gatifloxacin and moxifloxacin in terms of uncorrected visual acuity or best-corrected visual acuity at 3 months postoperatively.

CONCLUSION

No significant differences were found in the effects of the preservative-free fourth-generation fluoroquinolones gatifloxacin and moxifloxacin on epithelial healing after PRK.

A current practice for predicting ocular toxicity of systemically delivered drugs

The ability to predict ocular side effects of systemically delivered drugs is an important issue for pharmaceutical companies. Although animal models involving standard clinical ophthalmic examinations and postmortem microscopic examinations of eyes are still used to identify ocular issues, these methods are being supplemented with additional in silico, in vitro, and in vivo techniques to identify potential safety issues and assess risk. The addition of these tests to a development plan for a potential new drug provides the opportunity to save time and money by detecting ocular issues earlier in the program. This review summarizes a current practice for minimizing the potential for systemically administered, new medicines to cause adverse effects in the eye.

Comparison of fluoroquinolones: cytotoxicity on human corneal epithelial cells

PURPOSE

To compare the cytotoxicity of different fluoroquinolones (FQs) towards human corneal epithelial cells (HCECs).

METHODS

HCECs were incubated with FQs (norfloxacin, ciprofloxacin, ofloxacin, levofloxacin, moxifloxacin, and gatifloxacin), both as commercial ophthalmic formulations and as unpreserved solutions. Cells incubated in different formulations of gentamicin, cefazolin, and benzalkonium chloride (BAC) were also compared. A cell viability assay, using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay, was used to evaluate the drug effects on cell viability after five incubation times (30 min, 1 h, 4 h, 8 h, and 24 h). Transepithelial electrical resistance (TEER) was measured with a voltohmmeter to help understand changes in paracellular permeability at five time points (4 h, 8 h, 12 h, 24 h, and 48 h). Cell morphology was observed with an inverted fluorescence microscope, with multiple stage position and in time-lapse mode.

RESULTS

The preserving solutions and BAC at concentrations above 0.005% significantly decreased cell viability, when assayed by MTS. Increased paracellular permeability and decreased membrane integrity were also observed by TEER measurements and inverted fluorescence microscopy. Ofloxacin and levofloxacin were both free of preservatives and showed the least cytotoxicity towards HCECs in commercial FQ eye drops.

CONCLUSIONS

The cytotoxicity observed with FQ eye drops seems to be caused mainly by the preservative, which induced a significant decrease in membrane integrity and increased paracellular permeability. We found the new generation of FQs (moxifloxacin and gatifloxacin) no less cytotoxic towards HCECs than the old generation ones.