Fungal Keratitis: Diagnosis, Management, and Recent Advances

Abstract

Fungal keratitis is one of the major causes of microbial keratitis that may lead to corneal blindness. Many problems related to diagnosis and therapy are encountered in fungal keratitis, including difficulty in obtaining laboratory diagnoses and the availability and efficacy of antifungal medications. Intensive and prolonged use of antifungal topical preparations may not be enough. The use of antifungal medications is considered the main treatment for fungal keratitis. It is recommended to start antifungal therapy after confirmation of the clinical diagnosis with a smear or positive cultures. Topical application of antifungal medications is a mainstay for the treatment of fungal keratitis; however, systemic, intra-stromal, or intra-cameral routes may be used. Therapeutic keratoplasty is the main surgical procedure approved for the management of fungal keratitis with good success rate. Intrastromal corneal injection of antifungal medications may result in steady-state drug levels within the corneal tissue and prevent intervals of decreased antifungal drug concentration below its therapeutic level. In cases of severe fungal keratitis with deep stromal infiltration not responding to treatment, intracameral injection of antifungal agents may be effective. Collagen cross-linking has been proposed to be beneficial for cases of fungal keratitis as a stand-alone therapy or as an adjunct to antifungal medications. Although collagen cross-linking has been extensively studied in the past few years, its protocol still needs many modifications to optimize UV fluence levels, irradiation time, and concentration of riboflavin to achieve 100% microbial killing.

Keywords:

• fungal keratitis
• keratomycosis
• PACK-CXL
• antifungal
• voriconazole
• intracorneal injection
• targeted therapy

Abbreviations

AC, Anterior chamber; AI, Artificial intelligence; CXL, Corneal collagen cross-linking; DALK, Deep anterior lamellar keratoplasty; H&E, Hematoxylin and Eosin; IVCM, In vivo confocal microscopy; MK, Mycotic Keratitis; MUTT, Mycotic ulcer treatment trial; PAS, Periodic Acid-Schiff; PACK-CXL, Photo-Activated Chromophore for Keratitis – Collagen Cross-linking; PDAT, Photo-Dynamic Antimicrobial Therapy; PCR, Polymerase chain reaction; KOH, Potassium Hydroxide; ROS, Reactive oxygen species; SDA, Sabouraud dextrose agar; TST, Topical, systemic and targeted therapy; TKP, Therapeutic keratoplasty; UVA, Ultraviolet A.

Data Sharing Statement

The data used to support the findings of this study are available from the corresponding author upon request.

Disclosure

The authors report no conflicts of interest in this work.