Efficacy of antifungal agents in the cornea. IV. Amphotericin B methyl ester

Quantitative mycologic techniques were used to evaluate the efficacy of topical amphotericin B methyl ester in two models of yeast infection in rabbit eyes. Doses of 1%, 0.5%, and 0.15% were used in a model of superficial Candida albicans infection. The 1% dose of drug was highly efficacious, abolishing the disease after 2 days of treatment. With doses of 0.5% and 0.15%, decreasing efficacy was observed. Antifungal activity did not deteriorate when 1% prednisolone acetate was administered concomitantly with the 1% dose. In a model of deep stromal infection, the administration of topical 1% amphotericin B methyl ester was highly efficacious when the corneal epithelium was absent. Even in corneas with intact epithelium, a reduced though still significant effect was noted.     

Influence of the corneal epithelium on the efficacy of topical antifungal agents

A model of deep stromal Candida albicans infection was established by injecting 25 microliters of a suspension containing 5 X 10(9) colony forming units/ml of the yeast into corneas of pigmented rabbits. In this model, the infection lasts for more than 8 days. Using quantitative techniques, the authors compared the efficacy of six topical antifungal agents in the presence of an intact epithelium and in corneas debrided of epithelium. In corneas debrided on a daily basis, the polyenes (amphotericin B 0.15% and 0.075% and natamycin 5%) exhibited a significant antifungal effect. When the epithelium was left intact, 5% natamycin and 0.075% amphotericin B were without effect, while the efficacy of the 0.15% preparation of amphotericin B was much reduced. Removal of the epithelium appeared to affect adversely the efficacy of flucytosine. The imidazoles were not efficacious in this model.     

Development of quantitative methods of measuring antifungal drug effects in the rabbit cornea.

By means of multiple inoculation in each cornea with microtrephination a highly reproducible quantitative model of fungal infection of the rabbit corneal stroma has been produced. A known suspension of the chosen pathogen was systematically implanted into the trephine sites in the cornea. The degree of infectivity was monitored in both the preinoculation treated corneae (prophylaxis) and the postinoculation treated corneae (therapy). Examples measuring and comparing the antifungal effect of various imidazole drugs against Candida albicans are discussed.     

Efficacy of iontophoresis in the rat cornea

Background: Iontophoresis can enhance penetration of drugs into tissues. We examined the extent of penetration of gentamicin into the cornea of rats during iontophoresis and the effect of varying the concentrations of gentamicin, the duration of iontophoresis and the current densities during iontophoresis. Methods: Eight groups of rats underwent corneal iontophoresis using gentamicin dissolved in agar. Low and high concentrations of gentamicin were used, as well as low and high current densities and long and short durations of iontophoresis. Control groups received topical or subconjunctival gentamicin, topical saline solution and mock iontophoresis with the agar-gentamicin mixture. The Mann-Whitney test was used for statistical evaluation. Results: Highly bactericidal concentrations of gentamicin were obtained in all the iontophoresis-treated corneas. The high concentration compared to the low concentration of gentamicin in agar significantly increased the concentration of gentamicin in the corneas, as did the longer duration of iontophoresis. However, higher current intensity did not significantly enhance the drug concentration in the cornea. Conclusion: lontophoresis with a concentrated gentamicin-agar mixture may provide a rapid increase of levels in the cornea.     

Automutilation of the cornea II. Psychiatric aspects

In connection with a number of ophthalmological patients in whom automutilation was seen, the background to this behaviour is considered. It is usually seen in patients with a borderline personality. Automutilants differ from simulants.In practice, it is important to avoid confrontation and to look out for splitting. Psychiatric treatment is seldom successful.     

Efficacy of acycloguanosine against herpetic ulcers in rabbit cornea.

The effect of a new antiherpetic compound of very low toxicity called acycloguanosine (Wellcome 248U) on herpetic ulcers in rabbit cornea was studied by the Corneal Epithelial Lesion Therapeutic Assay (CELTA). The therapeutic effect of 3% acycloguanosine ointment on dendritic ulcers was equal to that of 0.5% 5-iodo-2'-deoxyuridine (IDU) ointment. No toxic symptoms could be detected by slit-lamp on 4 days' treatment with this concentration of acycloguanosine. Because of its selective action on virus only, its extremely low toxicity in animals, and its availability for systemic administration, acycloguanosine seems to be an ideal antiviral compound for use in the treatment not only of herpetic keratitis but also of other herpetic diseases in man.     

Fungal infections of the eye--current antifungal agents

Antifungal agents used in ocular infections are presented. The most common etiology of fungal infections is described. Mechanisms and range of action, available drugs and the latest groups of antifungal agents during clinical trials are presented.     

Refractive surgery of the cornea. II. Operations with excimer laser]

Discussed are the possibilities of application of excimer laser for the correction of myopia, astigmatism and hypermetropia, based on personal material and survey of the literature. The results obtained hitherto submit a considerable hope for utilization of the presented method in the future.