ABSTRACT
PURPOSE: To assess the impact of topical anesthetic agents and ethanol on ocular surface wound healing using an ex vivo whole-globe porcine model. SETTING: Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland. DESIGN: Experimental study. METHODS: Standardized corneoepithelial lesions (5.0 mm diameter, 40 µm depth) were created with excimer laser light in freshly enucleated porcine eyes. The globes (6 per group) were exposed to different concentrations of ethanol (2.0% to 99.0%), cocaine (2.0% to 10.0%), procaine hydrochloride (0.4%), tetracaine (0.5% to 1.0%), or lidocaine (2.0%), 3 drops/hour for 3 hours. Control solutions were physiologic saline, balanced salt solution, and tissue-culture medium. After 20 to 26 hours, wound-healing response was compared by measuring the diameter of each corneoepithelial lesion. RESULTS: The mean diameter of corneoepithelial lesions exposed to physiologic saline decreased from 4.78 mm ± 0.19 (SD) to 4.44 ± 0.17 mm between 20 and 26 hours. After 24 hours, the mean lesion size, compared with physiological saline, was larger after cocaine 5.0% (5.20 ± 0.26 mm) and 10.0% (5.39 ± 0.12 mm), tetracaine 0.5% (5.59 ± 0.35 mm) and 1.0% (5.55 ± 0.27 mm), and procaine hydrochloride 0.4% (5.76 ± 0.12 mm), but not after lidocaine 2.0% (5.01 ± 0.17 mm). Balanced salt solution, tissue-culture medium, ethanol 2.0% to 99.0%, and cocaine 2.0% did not inhibit the wound-healing response. CONCLUSIONS: In an ex vivo whole-globe porcine model, lidocaine 2.0% and cocaine 2.0% were the least toxic anesthetic agents. At all concentrations, ethanol had no impact on wound healing. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.
Subject(s)
Anesthesia, Local/methods , Anesthetics, Local/toxicity , Epithelium, Corneal/drug effects , Ethanol/toxicity , Models, Animal , Wound Healing/drug effects , Administration, Topical , Animals , Cocaine/toxicity , Epithelium, Corneal/injuries , Keratectomy, Subepithelial, Laser-Assisted , Lasers, Excimer , Lidocaine/toxicity , Ophthalmic Solutions , Procaine/toxicity , Swine , Tetracaine/toxicityABSTRACT
BACKGROUND: An efficient epithelial wound healing is essential for the preservation of vision. Hence, the effects of novel topical drugs on the ocular surface must be ascertained before clinical use. We have tested the utility of an ex vivo, whole-globe porcine screening model to serve as a partial substitute for resource- and time-consuming animal experiments. METHODS: Standardized corneoepithelial lesions, 5.0 mm in diameter and 40 microm in depth, were created with an Excimer laser in freshly enucleated porcine eyes. These were then exposed to control solutions (physiological saline (baseline), tissue-culture medium (positive control) and NH4 + (toxicity control)) and to three test agents (cyclosporin A, dexamethasone, and mitomycin C). The wound-healing response and toxic effects were monitored after 20-26 h by comparing lesion sizes. RESULTS: According to baseline data obtained using physiological saline, tissue-culture medium improved wound healing. The highest doses of NH4 + (1 M) and mitomycin C (1.0 mg/mL) elicited toxic effects (confidence interval according to Scheffé's post hoc test: -0.65 to -0.07 and -0.99 to -0.60, respectively). Under the same test conditions, cyclosporin A (0.1 to 10 mg/mL) and dexamethasone (0.1 to 10 mg/mL) had no influence on corneoepithelial wound healing. CONCLUSIONS: Drug screening with this ex vivo porcine model permits a reproducibly quantitative and time- and dose-dependent assessment of corneoepithelial wound healing. This model corresponds more closely to the clinical situation than cell culturing and may, therefore, be useful in evaluating novel pharmaceutical agents, thereby helping to cut down on the number of animal experiments performed prior to the instigation of clinical trials.
Subject(s)
Cyclosporine/pharmacology , Dexamethasone/pharmacology , Epithelium, Corneal/injuries , Mitomycin/pharmacology , Wound Healing/drug effects , Animals , Dose-Response Relationship, Drug , Epithelium, Corneal/drug effects , Models, Animal , SwineABSTRACT
The purpose of this study was to compare the local and systemic Toxoplasma-specific humoral immune responses in individuals with ocular toxoplasmosis (OT). To this end, paired aqueous humor and serum samples from 46 individuals with active OT and from 30 individuals without inflammatory eye disease (controls) were analyzed by immunoblotting for anti-Toxoplasma immunoglobulin G (IgG), IgA, IgM, and IgE directed against 20- to 120-kDa antigens. The presence in the aqueous humor of a unique band, or of at least three bands that were at least three times more intense in aqueous humor than in serum, was taken as evidence of local antibody production. IgG bands were detected in 98% of the aqueous humor samples, while IgA bands were detected in 76%, IgM bands were detected in 8%, and IgE bands were not detected in any. Evidence of local production of specific antibodies was found in 32 cases (70%) (IgG in 23 [50%]; IgA in 16 [35%]). In 10 instances (22%), routine laboratory tests were not indicative of OT. In 14 cases (30%), no local antibody production was detected by immunoblotting; 3 of these cases yielded evidence of local antibody production according to the Goldmann-Witmer coefficient. Local antibody production was revealed for 7 of the 30 controls (23%). Hence, the sensitivity of immunoblotting for IgG and IgA is 70%, and the specificity is 77%. We conclude that immunoblotting for local specific IgG and IgA supports the clinical diagnosis of OT in 70% of cases. In 22% of these, the diagnosis is not confirmed by other laboratory tests. Hence, immunoblotting increases the sensitivity of routine laboratory tests and should be considered for samples that register negative by such tests.
