Illustration of an eye affected by a feathery fungal infection on the cornea.

Vision Under Attack: Unmasking the Rare Fungal Threat of Bipolaris Keratitis

Elliot Brynn in Health & Wellness November 2025 • 4 min read.

"Learn how this unusual fungal infection can compromise corneal health and what steps can be taken to protect your sight."

Fungal keratitis represents a significant threat to vision, especially in tropical and subtropical regions, where it is a relatively common cause of corneal infections. The majority of these infections are caused by filamentous fungi, with Aspergillus and Fusarium species being the most commonly identified culprits worldwide. However, a growing concern is the rise of dematiaceous fungi as causative agents of corneal ulcers.

Among these, species of Curvularia and Bipolaris are increasingly recognized as significant contributors to keratomycosis. Bipolaris hawaiiensis, a darkly pigmented fungus, is known to cause subcutaneous, cutaneous, and soft tissue infections referred to as phaeohyphomycosis. While typically associated with plant material, grasses, and soil, Bipolaris hawaiiensis can also lead to bronchopulmonary disease, encephalitis, and, in rare instances, ocular infections.

Given the potential severity of such infections, understanding the causes, symptoms, and treatments for Bipolaris keratitis is crucial for healthcare providers and individuals at risk. Early diagnosis and appropriate management are key to preventing vision loss and improving patient outcomes. This article aims to shed light on the rare but serious threat of Bipolaris keratitis, offering insights into its identification, treatment, and prevention.

What are the Symptoms and How Is It Diagnosed?

Illustration of an eye affected by a feathery fungal infection on the cornea.

A recent case study detailed a 63-year-old male who developed Bipolaris keratitis following a traumatic eye injury involving sawdust. The patient, who already had ocular hypertension in the other eye, initially presented with symptoms that led to a misdiagnosis of a simple corneal ulcer at a local hospital. Despite treatment with amphotericin B, his condition did not improve, necessitating a referral to a specialized ophthalmological department.

Upon examination, the patient exhibited decreased vision and photophobia. His visual acuity was significantly reduced in the affected eye. Doctors observed key signs, including a whitish infiltration with a feathery edge and a brownish pigmented lesion in the central cornea. Corneal thinning and mild anterior chamber inflammation were also noted. This combination of symptoms prompted immediate diagnostic actions.

Microscopic Examinations: The corneal lesion was scraped for thorough microscopic analysis, including KOH examination, Gram staining, and calcofluor-white staining, to identify the presence and nature of fungal elements.
Confocal Microscopy: Confocal microscopy was employed to visualize the structure of the hyphae in real-time, aiding in the identification of fungal characteristics such as acute angle branching.
Fungal Culture: A fungal culture was performed to grow and identify the specific species of fungi involved, which is critical for tailoring the antifungal treatment.

The diagnostic process confirmed the presence of numerous septate hyphae, leading to the identification of Bipolaris spp. Further nucleotide sequence analysis specifically identified Bipolaris hawaiiensis as the causative agent. These diagnostic measures are critical in accurately identifying the rare fungal infection, distinguishing it from more common causes of keratitis and guiding the appropriate therapeutic interventions.

Protecting Your Sight: The Importance of Early Action

Bipolaris hawaiiensis is a virulent organism that can cause ocular morbidity and blindness, early diagnosis and accurate identification of the pathogenic B. hawaiiensis can lead to prompt and appropriate treatment and prevent ocular morbidity and blindness. In refractory B. hawaiiensis keratomycosis, therapeutic penetrating keratoplasty should be considered to remove the infected corneal tissue and recalcitrant corneal plaque and to improve visual acuity.

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Everything You Need To Know

What is Bipolaris keratitis and why is it a threat to vision?

Bipolaris keratitis is an uncommon but serious fungal infection of the cornea caused by the dematiaceous fungi, particularly the species of Bipolaris, such as Bipolaris hawaiiensis. This infection is a threat to vision because the Bipolaris hawaiiensis is a virulent organism. If left untreated or misdiagnosed, Bipolaris keratitis can lead to significant corneal damage, causing vision loss or even blindness. Early diagnosis and treatment are therefore crucial to prevent severe ocular morbidity and preserve sight.

What are the typical symptoms of Bipolaris keratitis, and how does it differ from other corneal infections?

Symptoms of Bipolaris keratitis include decreased vision and photophobia, as well as signs like a whitish infiltration with a feathery edge and a brownish pigmented lesion in the central cornea. Corneal thinning and mild anterior chamber inflammation may also be present. These symptoms, especially the presence of a pigmented lesion, help distinguish it from other more common corneal infections. The use of microscopic examinations, confocal microscopy, and fungal cultures are critical to accurately identify the specific fungal species, which is essential because they determine the appropriate antifungal treatment.

How is Bipolaris keratitis diagnosed, and what diagnostic tools are employed?

The diagnosis of Bipolaris keratitis involves a combination of clinical observation and laboratory tests. A key diagnostic process includes scraping the corneal lesion for microscopic analysis, including KOH examination, Gram staining, and calcofluor-white staining to identify fungal elements. Confocal microscopy is used to visualize the structure of the hyphae in real-time. A fungal culture is performed to grow and identify the specific Bipolaris species. Further nucleotide sequence analysis is also used to identify the causative agent, such as Bipolaris hawaiiensis. These diagnostic steps confirm the presence of the infection and guide treatment decisions, differentiating it from other types of keratitis.

What are the risk factors associated with Bipolaris keratitis, and how can it be prevented?

The risk factors associated with Bipolaris keratitis include traumatic eye injuries, especially those involving exposure to plant material, grasses, or soil, which can introduce the Bipolaris hawaiiensis fungus. Individuals with weakened immune systems or those in tropical and subtropical regions, where fungal infections are more common, may also be at higher risk. Prevention involves protecting the eyes from injury, especially in environments where fungal exposure is possible. Early medical attention for any corneal injury or infection is crucial to prevent the development of Bipolaris keratitis.

What treatments are available for Bipolaris keratitis, and what happens if the infection does not respond?

The primary treatment for Bipolaris keratitis involves the use of antifungal medications. However, in cases of refractory Bipolaris keratomycosis, therapeutic penetrating keratoplasty should be considered to remove the infected corneal tissue. Early and accurate identification of Bipolaris hawaiiensis is essential for prompt and appropriate treatment to prevent ocular morbidity and blindness. If initial treatments are not effective, surgical options, such as corneal transplantation, may be necessary to restore vision and prevent further damage. The choice of treatment depends on the severity of the infection and the patient's response to therapy.