Microbial corneal infection is the most serious and "most common vision threatening" [1] [2] complication of contact lens wear, [1] which is believed to be strongly associated with contact lens cases. [1] Such infections "are being increasingly recognized as an important cause of morbidity and blindness" [2] and "may even be life-threatening." [2] While the cornea is believed to be the most common site for fungal eye infections, other parts of the eye such as the orbit, sclera, eyelids, and more may also be involved. [2] Contact lens cases are recognized as a "potential source of pathogens associated with corneal ulcers" [1] and according to Moorfields Eye Hospital, contact lens wear is “the most prevalent risk factor for new cases of corneal ulcers.” [1] Contaminants "isolated from contact lens associated corneal ulcers have often been shown to be" [1] the same as found in the patient's contact lens case, thus providing evidence contaminated contact lens cases may be a "replenishable source of pathogenic microbes." [1]
In the study Acanthamoeba, bacterial, and fungal contamination of contact lens storage cases, “101 asymptomatic daily wear cosmetic contact lens wearers” [1] from one contact lens practice were studied to determine the occurrence of fungal, bacterial, and protozoal contamination of contact lens cases. [1] The results of this study found that 24% of “contact lens cases were colonized by fungi” [1] with a “majority growing Cladosporium species (10/24) or Candida species (9/24).” [1] Other fungi that were also isolated include Fusarium solani, Aspergillus versicolor, Exophiala , and Phoma . [1] Most of the fungi contaminants were also found to be associated with bacterial contaminants “but on three occasions, fungi were the only microbes isolated.” [1]
According to Current Perspectives on Ophthalmic Mycoses, [2] along with the previously mentioned genus and species of fungi, other species of fungi that predominate in ophthalmic mycoses are Scedosporium and "dematiaceous fungi." [2] One of the difficulties stated in this study is the accuracy of assessing the identification of the genus or species of the "fungal strain isolated in culture." [2] In one instance, a fungal strain previously identified as Arthrobotrys oligospora in a patient was "later re-identified as Cephaliophora irregularis." [2] In the same patient, the fungus isolated from "a retained contact lens was identified as Scedosporium prolificans ." [2] The issues of fungal identification observed as mentioned in this study do not pertain only to fungal contamination of contact lenses but also to the overall difficulties of fungal identification in vitro.
In the study In Vitro Interactions of Fusarium and Acanthamoeba with Drying Residues of Multipurpose Contact Lens Solutions, the "effects of evaporation and drying of multipurpose contact lens solution" [3] was observed on the survival of Fusarium . [3] The results of the study indicate that the drying effect of the disinfectant solution was not completely able to kill off Fusarium. [3] Fusarium was found to "aggregate immediately after introduction" [3] of the solution, indicating the invasive nature of Fusarium. The Fusarium were found to "redistribute themselves" [3] into "discrete regions of the dried residues" [3] which provides evidence that the use solely of multipurpose contact lens solution to prevent fungal contamination will not suffice. [3] Due to the findings of this study, it is suggested that regular replacement of contact lens cases is essential. [3]
Genus and species widely associated with fungal contamination of contact lenses include, but not limited to:
Factors which contribute to fungal contamination of contact lenses include, but not limited to, "hygiene negligence such as": [4]
Studies suggest a number of "recommendations for contact lens wearers to prevent contamination" [1] by both bacterial and fungal contaminants [1] which include:
Diagnosis is determined "by recognition of typical clinical features" [2] and through "direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples." [2] Ultimately, cultures made from the samples isolated from patients is what "confirms diagnosis." [2] Other tests that may also be used if needed include "histopathological, immunohistochemical, or DNA-based tests." [2] Pathogenesis of the fungal contaminants include a wide range of factors such as "invasiveness, toxigenicity, and host factors." [2]
Once diagnosis is accessed, "specific anti-fungal therapy" [2] can be administered. [2] One of the most popular and common treatments used "for life-threatening and severe ophthalmic mycoses" [2] is amphotericin B which is a specific anti-fungal drug. [2] For the treatment for filamentous fungal keratitis, "topical natamycin is usually the first choice." [2] For the treatment of yeast keratitis, "topical amphotericin B is usually the first choice." [2] Current advances in further treatments include evaluations of triazoles such as itraconazole and fluconazole "as therapeutic options in ophthalmic mycoses." [2]
For invasive fungal eye infections, scleritis, and keratitis, "medical therapy alone" [2] is usually not enough to treat the infections due to the invasive nature of certain species. [2] Such invasive fungi include Fusarium, Pythium, and Lasiodiplodia. [2] For these more serious type of infections which do not respond to medical therapy will need to be further treated by "surgical debridement" [2] and other "various surgical procedures." [2]
Many fungal eye infections will also be associated with corticosteroids, which methods "to control inflammatory tissue damage" is being sought. [2] Immediate treatment for fungal contaminated contact lenses is to discard the contact lenses in question and replace with brand new contact lenses. It is also recommended to replace the contact lens case as it may be a pathogenic source. [1] [3] Patients with eye infections caused by contaminated contact lenses should seek immediate help from a certified professional.
Contact lenses, or simply contacts, are thin lenses placed directly on the surface of the eyes. Contact lenses are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision or for cosmetic or therapeutic reasons. In 2010, the worldwide market for contact lenses was estimated at $6.1 billion, while the US soft lens market was estimated at $2.1 billion. Multiple analysts estimated that the global market for contact lenses would reach $11.7 billion by 2015. As of 2010, the average age of contact lens wearers globally was 31 years old, and two-thirds of wearers were female.
Acanthamoeba is a genus of amoebae that are commonly recovered from soil, fresh water, and other habitats. The genus Acanthamoeba has two stages in its life cycle, the metabolically active trophozoite stage and a dormant, stress-resistant cyst stage. In nature, Acanthamoeba species are generally free-living bacterivores. However, they are also opportunistic pathogens able to cause serious and sometimes fatal infections in humans and other animals.
Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired eyesight, photophobia, red eye and a 'gritty' sensation. Diagnosis of infectious keratitis is usually made clinically based on the signs and symptoms as well as eye examination, but corneal scrapings may be obtained and evaluated using microbiological culture or other testing to identify the causative pathogen.
Free-living amoebae are a group of protozoa that are important causes of infectious disease in humans and animals.
Orthokeratology, also referred to as Night lenses, Ortho-K, OK, Overnight Vision Correction, Corneal Refractive Therapy (CRT), Accelerated Orthokeretology, Cornea Corrective Contacts, Eccentricity Zero Molding, and Gentle Vision Shaping System (GVSS), is the use of gas-permeable contact lenses that temporarily reshape the cornea to reduce refractive errors such as myopia, hyperopia, and astigmatism.
ReNu is a brand of soft contact lens care products produced by Bausch & Lomb. By far the most popular brand of lens solutions until 2006, ReNu has rebranded its formulations as renu sensitive and renu fresh, the latter containing a patented ingredient called hydranate, known by chemists as hydroxyalkylphosphonate, that removes protein deposits and can eliminate the need for a separate enzymatic cleaner.
Eumycetoma, also known as Madura foot, is a persistent fungal infection of the skin and the tissues just under the skin, affecting most commonly the feet, although it can occur in hands and other body parts. It starts as a painless wet nodule, which may be present for years before ulceration, swelling, grainy discharge and weeping from sinuses and fistulae, followed by bone deformity.
Artificial tears are lubricating eye drops used to relieve dryness and irritation of the ocular surface. Dry eye syndrome is a common ocular surface disorder and is characterized by disruption of the tear film and increased inflammation.
Corneal abrasion is a scratch to the surface of the cornea of the eye. Symptoms include pain, redness, light sensitivity, and a feeling like a foreign body is in the eye. Most people recover completely within three days.
Acanthamoeba keratitis (AK) is a rare disease in which amoebae of the genus Acanthamoeba invade the clear portion of the front (cornea) of the eye. It affects roughly 100 people in the United States each year. Acanthamoeba are protozoa found nearly ubiquitously in soil and water and can cause infections of the skin, eyes, and central nervous system.
Fungal keratitis is a fungal infection of the cornea, which can lead to blindness. It generally presents with a red, painful eye and blurred vision. There is also increased sensitivity to light, and excessive tears or discharge.
Corneal neovascularization (CNV) is the in-growth of new blood vessels from the pericorneal plexus into avascular corneal tissue as a result of oxygen deprivation. Maintaining avascularity of the corneal stroma is an important aspect of healthy corneal physiology as it is required for corneal transparency and optimal vision. A decrease in corneal transparency causes visual acuity deterioration. Corneal tissue is avascular in nature and the presence of vascularization, which can be deep or superficial, is always pathologically related.
Johnson & Johnson Vision (JJV) is a subsidiary of Johnson & Johnson and is composed of two divisions, Johnson & Johnson Surgical Vision and Johnson & Johnson Vision Care. Services include Intraocular lenses, laser vision correction systems, phacoemulsification systems, viscoelastic, Microkeratomes and related products used in cataract and refractive surgery.
Corneal ulcer, also called keratitis, is an inflammatory or, more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and in farming. In developing countries, children afflicted by vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes persisting throughout life. In ophthalmology, a corneal ulcer usually refers to having an infection, while the term corneal abrasion refers more to a scratch injury.
Fusarium solani is a species complex of at least 26 closely related filamentous fungi in the division Ascomycota, family Nectriaceae. It is the anamorph of Nectria haematococca. It is a common soil inhabiting mold. Fusarium solani is implicated in plant diseases as well as in serious human diseases such as fungal keratitis.
Exophiala jeanselmei is a saprotrophic fungus in the family Herpotrichiellaceae. Four varieties have been discovered: Exophiala jeanselmei var. heteromorpha, E. jeanselmei var. lecanii-corni, E. jeanselmei var. jeanselmei, and E. jeanselmei var. castellanii. Other species in the genus Exophiala such as E. dermatitidis and E. spinifera have been reported to have similar annellidic conidiogenesis and may therefore be difficult to differentiate.
Exophiala dermatitidis is a thermophilic black yeast, and a member of the Herpotrichiellaceae. While the species is only found at low abundance in nature, metabolically active strains are commonly isolated in saunas, steam baths, and dish washers. Exophiala dermatitidis only rarely causes infection in humans, however cases have been reported around the world. In East Asia, the species has caused lethal brain infections in young and otherwise healthy individuals. The fungus has been known to cause cutaneous and subcutaneous phaeohyphomycosis, and as a lung colonist in people with cystic fibrosis in Europe. In 2002, an outbreak of systemic E. dermatitidis infection occurred in women who had received contaminated steroid injections at North Carolina hospitals.
Scedosporiosis is the general name for any mycosis – i.e., fungal infection – caused by a fungus from the genus Scedosporium. Current population-based studies suggest Scedosporium prolificans and Scedosporium apiospermum to be among the most common infecting agents from the genus, although infections caused by other members thereof are not unheard of. The latter is an asexual form (anamorph) of another fungus, Pseudallescheria boydii. The former is a "black yeast", currently not characterized as well, although both of them have been described as saprophytes.
Exophiala phaeomuriformis is thermophilic fungus belonging to the genus Exophiala and the family Herpotrichiellaceae. it is a member of the group of fungi known as black yeasts, and is typically found in hot and humid locations, such as saunas, bathrooms, and dishwashers. This species can cause skin infections and is typically classified as a Biosafety Risk Group 2 agent.
Peripheral Ulcerative Keratitis (PUK) is a group of destructive inflammatory diseases involving the peripheral cornea in human eyes. The symptoms of PUK include pain, redness of the eyeball, photophobia, and decreased vision accompanied by distinctive signs of crescent-shaped damage of the cornea. The causes of this disease are broad, ranging from injuries, contamination of contact lenses, to association with other systemic conditions. PUK is associated with different ocular and systemic diseases. Mooren's ulcer is a common form of PUK. The majority of PUK is mediated by local or systemic immunological processes, which can lead to inflammation and eventually tissue damage. Standard PUK diagnostic test involves reviewing the medical history and a completing physical examinations. Two major treatments are the use of medications such as corticosteroids or other immunosuppressive agents and surgical resection of the conjunctiva. The prognosis of PUK is unclear with one study providing potential complications. PUK is a rare condition with an estimated incidence of 3 per million annually.