Fungal keratitis
Encyclopedia
A fungal keratitis is an 'inflammation of the eye
's cornea
' (called keratitis
) that results from infection by a fungal organism. Keratomycosis is the Greek terminology equivalent of fungal keratitis - it is the fungal infection of the cornea
, the anterior part of the eye
which covers the pupil
. Those experiencing these symptoms are typically advised to immediately visit the appropriate eyecare professional.
Signs: The eyelids and adnexa involved shows edema and redness, conjuctiva is chemosed. Ulcer may be present. It is a dry looking corneal ulcer with satellite lesions in the surrounding cornea. Usually associated with fungal ulcer is hypopyon
which is mostly white fluffy in appearance. Rarely, it may extend to the posterior segment
to cause endophthalmitis
in later stages, leading to the destruction of the eye. (Note: Fungal endophthalmitis
is extremely rare)
Yeasts
ophthalmic suspension is the drug of choice for filamentous fungal infection. Fluconazole
ophthalmic solution is recommended for Candida infection of the cornea. Amphotericin B
eye drops may be required for non-responding cases, but can be quite toxic and requires expert pharmacist for preparation. Other medications have also been tried with moderate success. consult your eye care professional in any case as they will have the best treatment.
has a high number of cases with fungal keratitis, but poor reporting system prevents accurate data collection. Florida in US regularly reports cases of fungal keratitis, with Aspergillus and Fusarium spp. as the most common causes.
brand of soft contact lens
solutions made headlines regarding a report from the United States
Centers for Disease Control and Prevention
suggesting an increased incidence of a specific type of fungal keratitis (Fusarium
keratitis) in people using Bausch & Lomb
products. Bausch & Lomb subsequently suspended, then recalled, shipments of one particular product, ReNu with MoistureLoc.
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
's cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
' (called keratitis
Keratitis
Keratitis is a condition in which the eye's cornea, the front part of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves impaired eyesight.-Types:...
) that results from infection by a fungal organism. Keratomycosis is the Greek terminology equivalent of fungal keratitis - it is the fungal infection of the cornea
Cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Together with the lens, the cornea refracts light, with the cornea accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is...
, the anterior part of the eye
Human eye
The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
which covers the pupil
Pupil
The pupil is a hole located in the center of the iris of the eye that allows light to enter the retina. It appears black because most of the light entering the pupil is absorbed by the tissues inside the eye. In humans the pupil is round, but other species, such as some cats, have slit pupils. In...
. Those experiencing these symptoms are typically advised to immediately visit the appropriate eyecare professional.
Classification
Infectious keratitis can be bacterial, fungal or viral. Remarkable differences in presentation of the patient allows presumptive diagnosis by the eye care professional, helping in institution of appropriate anti-infective therapy.Clinical features
The symptoms of fungal keratitis are blurred vision, a red and painful eye that does not improve when contact lenses are removed, or on antibiotic treatment, increased sensitivity to light(photophobia), and excessive tearing or discharge. The symptoms are markedly less as compared to a similar bacterial ulcer.Signs: The eyelids and adnexa involved shows edema and redness, conjuctiva is chemosed. Ulcer may be present. It is a dry looking corneal ulcer with satellite lesions in the surrounding cornea. Usually associated with fungal ulcer is hypopyon
Hypopyon
Hypopyon is pus in the eye.It is a leukocytic exudate, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera. It is a sign of inflammation of the anterior uvea and iris, i.e. iritis, which is a form of anterior uveitis...
which is mostly white fluffy in appearance. Rarely, it may extend to the posterior segment
Posterior segment
The posterior segment is the back two-thirds of the eye that includes the anterior hyaloid membrane and all of the optical structures behind it: the vitreous humor, retina, choroid, and optic nerve....
to cause endophthalmitis
Endophthalmitis
Endophthalmitis is an inflammation of the internal coats of the eye. It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. Infectious etiology is the most common and various bacteria and fungi have been isolated as...
in later stages, leading to the destruction of the eye. (Note: Fungal endophthalmitis
Endophthalmitis
Endophthalmitis is an inflammation of the internal coats of the eye. It is a dreaded complication of all intraocular surgeries, particularly cataract surgery, with possible loss of vision and the eye itself. Infectious etiology is the most common and various bacteria and fungi have been isolated as...
is extremely rare)
Causes
Filamentous fungi- Aspergillus fumigatusAspergillus fumigatusAspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
- FusariumFusariumFusarium is a large genus of filamentous fungi widely distributed in soil and in association with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health...
spp.
Yeasts
- CandidaCandida (genus)Candida is a genus of yeasts. Many species are harmless commensals or endosymbionts of animal hosts including humans, but other species, or harmless species in the wrong location, can cause disease. Candida albicans can cause infections in humans and other animals, especially in immunocompromised...
Pathophysiology
The precipitating event for fungal keratitis is trauma with a vegetable / organic matter. A thorn injury, or in agriculture workers, trauma with a wheat plant while cutting the harvest is typical. This implants the fungus directly in the cornea. The fungus grows slowly in the cornea and proliferates to involve the anterior and posterior stromal layers. The fungus can break through the descemet's membrane and pass into the anterior chamber. The patient presents a few days or weeks later with fungal keratitis.Diagnosis
The diagnosis is made by an ophthalmologist/optometrist correlating typical history, symptoms and signs. Many times it may be missed and misdiagnosed as bacterial ulcer. A definitive diagnosis is established only after a positive culture report (lactophenol cotton blue, calcoflour medium), typically taking a week, from the corneal scraping. Recent advances have been made in PCR / immunologic tests which can give a much quicker result.Treatment and management
A presumptive diagnosis of fungal keratitis requires immediate empirical therapy. NatamycinNatamycin
Natamycin , also known as pimaricin, is a naturally occurring antifungal agent produced during fermentation by the bacterium Streptomyces natalensis, commonly found in soil. Natamycin has a very low solubility in water, however, natamycin is effective at very low levels. Most molds have an MIC of...
ophthalmic suspension is the drug of choice for filamentous fungal infection. Fluconazole
Fluconazole
Fluconazole is a triazole antifungal drug used in the treatment and prevention of superficial and systemic fungal infections. In a bulk powder form, it appears as a white crystalline powder, and it is very slightly soluble in water and soluble in alcohol. It is commonly marketed under the trade...
ophthalmic solution is recommended for Candida infection of the cornea. Amphotericin B
Amphotericin B
Amphotericin B is a polyene antifungal drug, often used intravenously for systemic fungal infections...
eye drops may be required for non-responding cases, but can be quite toxic and requires expert pharmacist for preparation. Other medications have also been tried with moderate success. consult your eye care professional in any case as they will have the best treatment.
Prognosis
The infection typically takes a long time to heal, since the fungus itself is slow growing. Corneal perforation can occur in patients with untreated or partially treated infectious keratitis and requires surgical intervention in the form of corneal transplantation.Prevention/Screening
Prevention of trauma with vegetable / organic matter, particularly in agricultural workers while harvesting can reduce the incidence of fungal keratitis. Wearing of broad protective glasses with side shields is recommended for people at risk for such injuries.Epidemiology
This disease is quite common in the tropics and with large agrarian population. IndiaIndia
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
has a high number of cases with fungal keratitis, but poor reporting system prevents accurate data collection. Florida in US regularly reports cases of fungal keratitis, with Aspergillus and Fusarium spp. as the most common causes.
Social impact
The loss of vision with fungal keratitis can be quite disabling in terms of economic impact and social consequences. Many people come with fungal keratitis in the only eye and thus become blind due to the disease. The lack of education and proper eye protection in such cases is evidently responsible for their plight.Notable cases
Recently, one particular product, ReNu with MoistureLocReNu
ReNu is a brand of soft contact lens care products produced by Bausch & Lomb. It was by far the most popular brand of lens solutions until 2006. The original products are still availabe as renu fresh and renu sensitive...
brand of soft contact lens
Contact lens
A contact lens, or simply contact, is a lens placed on the eye. They are considered medical devices and can be worn to correct vision, for cosmetic or therapeutic reasons. In 2004, it was estimated that 125 million people use contact lenses worldwide, including 28 to 38 million in the United...
solutions made headlines regarding a report from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
suggesting an increased incidence of a specific type of fungal keratitis (Fusarium
Fusarium
Fusarium is a large genus of filamentous fungi widely distributed in soil and in association with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health...
keratitis) in people using Bausch & Lomb
Bausch & Lomb
Bausch & Lomb, an American company based in Rochester, New York, is one of the world's leading suppliers of eye health products, such as contact lenses and lens care products today. In addition to this main activity, in recent years the area of medical technology has been developed...
products. Bausch & Lomb subsequently suspended, then recalled, shipments of one particular product, ReNu with MoistureLoc.