Table 1-2.
Treatments for fungal keratitis
| Category | Mechanism of action | Examples | Comments | Susceptibility |
|---|---|---|---|---|
| Polyenes | Bind to fungal cell wall ergosterol and disrupts it | Amphotericin B | Poor penetration; toxic to human cells at higher dose; its systemic use with antineoplastic agents or cyclosporine increases the risk of renal toxicity; may cause punctate epithelial erosions and occasionally a greenish discoloration of the cornea. | Candida 100 %, Aspergillus 50 %, Fusarium 50 % |
| Natamycin | Less toxic than amphotericin B. No oral form available. Variable Candida coverage | Aspergillus 100 %, Fusarium 100 % | ||
| Azoles (imidazoles and triazoles) | At low concentrations inhibit ergosterol synthesis, at higher concentrations appear to cause direct damage to cell walls | Voriconazole | Good cornea penetration and minimum toxicity. Topical as effective as intrastromal. | Candida 100 %, Aspergillus100 % Fusarium 100 % |
| Fluconazole | Oral form effective against Candida with deep penetration. Narrow coverage against filamentous organisms. Adjust dose for renal insufficiency; monitor for rash, and discontinue if progresses. | Candida 100 % | ||
| Itraconazole | Candida 100 %, Aspergillus 70 % | |||
| Posaconazole | Lowest MIC for Aspergillus in an in vitro study.42 Topical and oral posaconazole shown to effective against resistant ocular fusarium species in case reports.75,76 | Aspergillus Fusarium | ||
| Ketoconazole | Good concentration in anterior chamber by oral route; hepatotoxicity may occur; administer antacid, anticholinergics, or H2 blockers at least 2 hours after taking ketoconazole. Adverse effects including impotence, decreased libido, and gynecomastia. | Candida 100 % Aspergillus100 % Fusarium 50 % Culvaria spp | ||
| Fluorinated pyrimidines | Block fungal thymidine synthesis | Flucytosine | Emergence of resistance rapidly develops if used alone, has synergistic effect with azole or amphotericin B. Narrow efficacy if treating filamentous fungi. | Candida 100 %, Cryptococcus 100 % Aspergillus 20 % |
| Echinocandins | Block fungal cell wall beta-glucan synthesis | Capsofungin, micafugin, anidulafungin | Controversy over effectiveness in ocular infections. | Candida and Aspergillus |