The term “yeast infection” is often associated with common conditions like thrush or candidiasis, but the same group of organisms can affect the eye. An eye infection caused by yeast, a type of fungus, is classified as an ocular fungal infection. These infections are rare compared to bacterial or viral eye infections, but they can be severe. Seeking prompt treatment is important because a delayed response can lead to serious and permanent vision loss.
Understanding Ocular Fungal Infections
Fungal infections of the eye are categorized based on the part of the eye affected. The most common presentation is fungal keratitis, an infection of the cornea, the clear, dome-shaped front surface of the eye. A deeper and more severe form is endophthalmitis, where the infection penetrates inner structures, such as the vitreous humor.
Fungi are separated into two groups: filamentous fungi and yeasts. Yeast infections in the eye are typically caused by Candida species, particularly Candida albicans, the organism responsible for common systemic yeast infections. Candida is a normal resident on human skin and mucous membranes, but it only causes infection when the eye’s natural defenses are compromised.
The other major group, filamentous fungi like Fusarium and Aspergillus, are commonly found in soil and on plant matter. These tend to cause keratitis after an external injury. In contrast, Candida infections are more often linked to pre-existing eye conditions or a weakened immune system.
Recognizing Symptoms and Risk Factors
Fungal eye infections often progress more gradually than bacterial infections, sometimes taking days or weeks to become noticeable. Symptoms can mimic other types of eye infections, making self-diagnosis unreliable. Common indicators include significant eye pain that seems disproportionate to the injury and noticeable eye reddening.
Patients often experience blurred vision and sensitivity to light. A foreign body sensation, or the feeling that something is stuck in the eye, is a frequent complaint. The eye may produce excessive tearing and a discharge, sometimes thick or white in appearance.
The presence of an eye injury involving plant matter, such as a poke from a thorn or tree branch, is a major risk factor for filamentous fungal infection. Improper use and care of contact lenses remain a primary cause of infection for the general public. This includes wearing lenses too long, sleeping in them, or using contaminated solutions or cases.
Individuals with compromised immune systems, such as those with diabetes or HIV, are at a higher risk of developing a Candida infection that spreads from the bloodstream. Recent eye surgery or the long-term use of topical corticosteroid eye drops can suppress the local immune response. Any new or worsening eye symptoms following a potential exposure or injury should be evaluated by an eye care professional immediately.
Medical Diagnosis and Treatment Protocols
Diagnosing a fungal eye infection begins with a thorough clinical examination, often using a slit lamp microscope to view the cornea’s layers. A definitive diagnosis requires identifying the specific fungal organism, achieved by taking a small sample of the infected tissue. This procedure, called a corneal scraping, is performed by gently collecting material from the surface of the ulcer.
The collected sample is sent for laboratory analysis using two primary methods. Smear microscopy provides a rapid, presumptive result; the sample is stained and examined under a microscope for fungal elements. Culturing, which involves placing the sample on special growth media like Sabouraud dextrose agar, remains the gold standard for definitive diagnosis and species identification.
Treatment for fungal keratitis is challenging because fungal cells are difficult to eliminate, and the infection often penetrates deep into the corneal tissue. Initial treatment involves high-dose prescription antifungal eye drops, such as natamycin or amphotericin B, applied frequently, sometimes every hour. Depending on the severity, oral antifungal medications, like voriconazole, may be prescribed to reach the deeper layers of the eye.
Treatment often lasts for several months, and compliance with the medication schedule is necessary to prevent recurrence and complications. If the infection does not respond to medication, or if the cornea has become severely scarred or perforated, surgical intervention may be necessary. This can include a corneal transplant, where the infected tissue is removed and replaced with a healthy donor cornea.
Preventing Eye Yeast Infections
Preventing fungal eye infections centers on hygiene and avoiding environmental exposures. For contact lens wearers, the most important rule is to never expose lenses or their storage case to tap water, as it is not sterile and can harbor fungi. This includes avoiding showering or swimming while wearing lenses.
Contact lens solution should always be fresh, and wearers should never “top off” old solution with new, as this dilutes the disinfectant. Proper lens care involves several steps:
- Rub and rinse the lenses with the recommended solution, even if the product is labeled as a “no-rub” formula.
- Rinse the contact lens case with solution.
- Air-dry the case.
- Replace the case completely every three to six months.
Individuals who work outdoors, particularly in gardening or farming, should always wear protective eyewear. This precaution helps prevent eye trauma from plant matter, a common way for filamentous fungi to be introduced directly into the cornea. General hand hygiene, by washing hands thoroughly before touching the eyes or handling lenses, also reduces the risk of accidental fungal transfer.