From Clinical Suspicion to Diagnosis: A Review of Diagnostic Approaches and Challenges in Fungal Keratitis

Abstract

Fungal keratitis is a relatively rare yet severe ocular infection that can lead to profound vision impairment and even permanent vision loss. Rapid and accurate diagnosis plays a crucial role in the effective management of the disease. A patient’s history establishes the initial clinical suspicion since it can provide valuable clues to potential predisposing factors and sources of fungal exposure. Regarding the evaluation of the observed symptoms, they are not exclusive to fungal keratitis, but their timeline can aid in distinguishing fungal keratitis from other conditions. Thorough clinical examination of the affected eye with a slit-lamp microscope guides diagnosis because some clinical features are valuable predictors of fungal keratitis. Definitive diagnosis is established through appropriate microbiological investigations. Direct microscopic examination of corneal scrapings or biopsy specimens can assist in the presumptive diagnosis of fungal keratitis, but culture remains the gold standard for diagnosing fungal keratitis. Advanced molecular techniques such as PCR and MALDI-ToF MS are explored for their rapid and sensitive diagnostic capabilities. Non-invasive techniques like in vivo confocal microscopy (IVCM) and optical coherence tomography (OCT) are useful for real-time imaging. Every diagnostic technique has both advantages and drawbacks. Also, the selection of a diagnostic approach can depend on various factors, including the specific clinical context, the availability of resources, and the proficiency of healthcare personnel.

Etiopathology, Epidemiology, Diagnosis, and Treatment of Fungal Keratitis

“…A particular rRNA gene region has been amplified in most studies using the PCR method to diagnose fungal keratitis. Because rRNA genes are very similar in many fungal species, this preference develops . PCR could be performed across numerous clinical samples, including corneal scrapings/biopsies, lacrimal fluid, or aqueous humor, with the need for a tiny bit of sample volume .…”

“…Because rRNA genes are very similar in many fungal species, this preference develops. 110 PCR could be performed across numerous clinical samples, including corneal scrapings/biopsies, lacrimal fluid, or aqueous humor, with the need for a tiny bit of sample volume. 111 This technique enables the identification of even minuscule quantities of fungal DNA, hence enhancing the precision of diagnosis, particularly in instances when there is just a small quantity of fungal presence.…”