Researchers are exploring the rising global prevalence of mycotic keratitis caused by uncommon fungal species. In a new systematic review and meta-analysis, they analyzed data from 566 studies across 61 countries and documented 10,436 cases of mycotic keratitis that were attributed to 154 rare fungal genera or species.
“Infectious keratitis is a major cause of corneal blindness and one of the leading causes of preventable blindness worldwide,” wrote lead study author Megha Gautam, of the Department of Ophthalmology at Bhopal Memorial Hospital and Research Centre in India, and colleagues. “Out of all the etiologic causes of infectious keratitis, mycotic keratitis (MK) poses a substantial global health concern with incidence ranging between 1% and 44%,” they added.
Using cultures, polymerase chain reaction, microscopy, and mass spectrometry, the researchers identified MK cases and fungal species. The pooled prevalence of MK caused by uncommon fungal species was estimated at 23% (95% confidence interval [CI] = 21%–25%). Country-specific and continental analyses revealed the highest prevalence in Pakistan (52%), Taiwan (43%), and Australia (37%), but the most reported cases were in India (99 studies, 5,778 isolates) and China (2,309 isolates). The most common species were Curvularia (25.37%), Alternaria (16.77%), Acremonium (9.57%), Penicillium (7.8%), and Bipolaris (7.46%). The lowest prevalence was found in the United Kingdom (9%).
Environmental and occupational factors, especially in tropical and subtropical regions, were major contributors to disease prevalence. The researchers also noted that advanced diagnostic tools are often underutilized in regions with high disease burden because of cost and limited access.
Patients were, on average, 50.5 years of age (range = 5–87) and were predominately male (67%). Farmers were the most affected group (N = 139 in 92 studies), and the primary risk factor was ocular trauma (598 cases), particularly with vegetative matter (229 cases). Other contributors included postsurgical infections, contact lens use, steroid exposure, and diabetes.
Among the patients reviewed, 98.6% received antifungals, including natamycin, voriconazole, amphotericin B, ketoconazole, and itraconazole. Combination therapies (eg, voriconazole plus terbinafine or caspofungin) were used for resistant strains such as Tintelnotia and Alternaria. Some patients (15%) required adjunctive treatments such as intrastromal or intracameral drug delivery, whereas surgical interventions—primarily corneal transplantation—were required in 40.9% of cases. Repeat keratoplasties were reported in persistent infections involving Arthrographis, Rhodotorula, and Purpureocillium species.
Visual acuity of LogMAR 1.3 or greater was achieved in 83.4% (n = 407/488) of cases. Structural integrity was preserved in 84.1% (n = 244/290) of cases, while 14.8% developed disfigurement or phthisis. Highly virulent fungi (eg, Scedosporium, Schizophyllumcommune, and Trichophyton) were associated with poor outcomes despite aggressive treatment.
The study was among the first global estimates of MK caused by uncommon fungi. “Contrary to conventional beliefs, our research reveals that uncommon fungal genera/species are more prevalent than previously thought,” the study authors wrote.
They suggested that multidisciplinary teams of ophthalmologists, microbiologists, and infectious disease experts can “ensure comprehensive care and optimal outcomes for patients with rare MK.”
The authors reported no conflicts of interest.