Introduction:

Fungal keratitis is a critical ocular infection that can have devastating consequences for patients’ vision. It is brought on by a variety of fungal species that can colonise human tissue, and its prevalence is rising globally. In this article, we will look at the aetiology, risk factors, diagnosis, and management of fungal keratitis in order to help eye care professionals understand and effectively treat this condition.

Etiology and Risk Factors:

Numerous fungi, including Candida species, Aspergillus species, Fusarium species, Cladosporium species, Curvularia species, and Rhizopus species, can result in fungal keratitis. Trauma, ocular surface disorders, and topical steroid use are risk factors for fungal keratitis. Geographical location and temperature can affect the types and prevalence of fungus. In warmer climates, filamentous fungi like Fusarium spp. and Aspergillus spp. are more prevalent and frequently linked to trauma. In contrast, people in northern regions who are immunosuppressed or debilitated have historically been more vulnerable to yeast infections like Candida albicans. The distribution of fungal keratitis has shifted as a result of recent outbreaks linked to contact lens use, necessitating a high index of suspicion and more comprehensive medical approaches.

Diagnosis:

Early diagnosis of fungal keratitis is crucial for optimal outcomes. When corneal ulcers don’t respond to broad-spectrum antibiotics, or have satellite lesions, suspicion of a fungal infection should be borne in mind. A comprehensive medical history, which includes details about any injuries, ocular surface conditions, or long-term topical steroid use, can offer crucial hints. Physical examination includes determining the size and depth of the lesion as well as evaluating ocular surface illness, secretions, lid edema, and the presence of foreign bodies. The diagnosis may be aided by corneal scrapings or biopsies as well as specialised staining methods like Gomori, PAS, acridine orange, calcofluor white, or KOH. To get a reliable specimen, ocular biopsy may occasionally be required.

Management:

The management of fungal keratitis requires a multidimensional approach, often combining medical therapy with surgical interventions. Topical antifungal medications are the cornerstone of treatment. Natamycin 5% is a commercially available topical antifungal specifically formulated for ocular use. Amphotericin B, another polyene antifungal, is commonly used alone or in combination with natamycin. Voriconazole, a triazole antifungal, can be administered topically, orally, or via intrastromal injection. Oral posaconazole, a new generation triazole, has shown effectiveness against resistant Fusarium infections. Other antifungals such as miconazole, clotrimazole, ketoconazole, and echinocandin agents like caspofungin and micafungin may also be considered. Surgical debridement, conjunctival flaps, lamellar or penetrating keratoplasty, and therapeutic transplants may be necessary in refractory or advanced cases.

Credit: Yoanmb, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Follow-up and Prognosis:

Close medical follow-up is essential to monitor patients’ response to treatment and ensure adequate healing. If required, more corneal scrapings or biopsies can be performed. Regular assessments of intraocular pressure and monitoring for complications such as glaucoma or endophthalmitis are crucial. Despite therapy, visual outcomes can be poor, resulting in considerable visual loss, need for evisceration in some circumstances, and a significant number of cases requiring keratoplasty.

Conclusion:

Due to its complicated aetiology, numerous risk factors, and potential for serious vision loss, fungal keratitis presents significant challenges to eye care providers. Maintaining a high level of suspicion, timely diagnosis, and appropriate management are crucial in mitigating the impact of this condition. To provide patients with the best care possible, ophthalmologists, microbiologists, and other medical personnel must work collaboratively.

Top image Credit: Ufficio Comunicazione, Azienda Ospedaliera SS. Antonio e Biagio e Cesare Arrigo, Alessandria and Biblioteca Biomedica Centro di Documentazione, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons