Review

Authors: Philip Maier, Paola Kammrath Betancor, Thomas Reinhard...

BACKGROUND

Millions of people in Germany wear contact lenses every day. Deficient contact lens hygiene can lead to corneal infection. Contact lens-associated keratitis usually has a highly acute presentation and can cause long-term visual loss.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed, as well as on relevant metaanalyses, Cochrane reviews, and reports by national and international health care authorities.

RESULTS

23-94% of contact lens wearers report associated discomfort and eye problems. The annual incidence of contact lens-associated keratitis is 2-4/10 000. It is due to bacteria in 90% of cases, and much less commonly to acanthamoebae and fungi. The pathogens generally arrive with the contact lens on the surface of the eye and can penetrate into the corneal tissue because the tear film under the lens is not swept away from the ocular surface by the eyelids, and corneal epithelial changes are often present as well. Corneal infiltration that is diagnosed early is often self-limited, but advanced bacterial infection usually requires intense topical antibiotic treatment. Some severe infections can only be eradicated by emergency corneal transplantation; this is the case in 20-30 % of fungal and acanthamoebic infections.

CONCLUSION

The wearing of contact lenses, particularly soft ones, is associated with a risk of microbial keratitis if proper contact lens hygiene is not exercised. Contact lens-associated keratitis very rarely causes permanent damage to eyesight (0.6 cases per 10 000 contact lens wearers per year). The use of contact lenses always calls for meticulous care.

Topics: Humans; Corneal Ulcer; Keratitis; Contact Lenses; Cornea; Corneal Diseases

PubMed: 35912449
DOI: 10.3238/arztebl.m2022.0281

Review

Authors: P A Thomas, J Kaliamurthy

Mycotic keratitis (an infection of the cornea) is an important ocular infection, especially in young male outdoor workers. There are two frequent presentations: keratitis due to filamentous fungi (Fusarium, Aspergillus, phaeohyphomycetes and Scedosporium apiospermum are frequent causes) and keratitis due to yeast-like fungi (Candida albicans and other Candida species). In the former, trauma is usually the sole predisposing factor, although previous use of corticosteroids and contact lens wear are gaining importance as risk factors; in the latter, there is usually some systemic or local (ocular) defect. The clinical presentation and clinical features may suggest a diagnosis of mycotic keratitis; increasingly, in vivo (non-invasive) imaging techniques (confocal microscopy and anterior segment optical coherence tomography) are also being used for diagnosis. However, microbiological investigations, particularly direct microscopic examination and culture of corneal scrape or biopsy material, still form the cornerstone of diagnosis. In recent years, the PCR has gained prominence as a diagnostic aid for mycotic keratitis, being used to complement microbiological methods; more importantly, this molecular method permits rapid specific identification of the aetiological agent. Although various antifungal compounds have been used for therapy, management of this condition (particularly if deep lesions occur) continues to be problematic; topical natamycin and, increasingly, voriconazole (given by various routes) are key therapeutic agents. Therapeutic surgery, such as therapeutic penetrating keratoplasty, is needed when medical therapy fails. Increased awareness of the importance of this condition is likely to spur future research initiatives.

Topics: Antifungal Agents; Clinical Laboratory Techniques; Debridement; Fungi; Humans; Immunocompromised Host; Keratitis; Mycoses; Wounds and Injuries

PubMed: 23398543
DOI: 10.1111/1469-0691.12126

Review

Authors: Christopher Donovan, Eduardo Arenas, Ramesh S Ayyala...

Fungal corneal ulcers are an uncommon, yet challenging, cause of vision loss. In the United States, geographic location appears to dictate not only the incidence of fungal ulcers, but also the fungal genera most encountered. These patterns of infection can be linked to environmental factors and individual characteristics of fungal organisms. Successful management of fungal ulcers is dependent on an early diagnosis. New diagnostic modalities like confocal microscopy and polymerase chain reaction are being increasingly used to detect and identify infectious organisms. Several novel therapies, including crosslinking and light therapy, are currently being tested as alternatives to conventional antifungal medications. We explore the biology of Candida, Fusarium, and Aspergillus, the three most common genera of fungi causing corneal ulcers in the United States and discuss current treatment regimens for the management of fungal keratitis.

Topics: Antifungal Agents; Corneal Ulcer; Eye Infections, Fungal; Humans; Keratitis; Ulcer

PubMed: 34425126
DOI: 10.1016/j.survophthal.2021.08.002

Authors: Waleed K Alsarhani, Clara C Chan, Shelley R Boyd...

PURPOSE

The purpose of this study was to describe a case of monkeypox (MPX)-associated disciform keratitis.

METHODS

This is a case report.

RESULTS

A 36-year-old male patient presented to the infectious diseases clinic with a 1-week history of disseminated pustular skin lesions, a 4-day history of constitutional symptoms, and redness in the left eye. Testing of blood, 2 skin lesions, and a conjunctival swab confirmed the presence of MPX virus by polymerase chain reaction. On ophthalmologic examination on the 17th day of illness, there was a corneal epithelial ridge that stained with fluorescein with disciform corneal edema and underlying keratic precipitates. The patient was treated with oral tecovirimat 600 mg twice a day for 14 days and topical prednisolone acetate 1% 4 times daily, starting 2 days later. On completion of oral treatment, his corneal findings had resolved except for a small subepithelial scar at which time topical steroids were tapered.

CONCLUSIONS

MPX may cause disciform keratitis and scarring that closely resembles other ocular viral infections. Clinical trials are urgently needed to define the optimal management of human MPX infections and reduce vision loss.

Topics: Male; Humans; Adult; Mpox, Monkeypox; Keratitis; Glucocorticoids; Corneal Edema; Polymerase Chain Reaction

PubMed: 36729600
DOI: 10.1097/ICO.0000000000003171

Authors: E C Ledbetter, S G Kim, D M Schaefer...

Pathogenic free-living amoebae, most notably Acanthamoeba spp., are important pathogens of the human cornea. The importance of infection with free-living amoebae in cats with keratitis is currently unclear. The aim of this study was to determine the frequency of amoeba detection in corneas of cats with naturally-acquired keratitis and in the ocular surface microflora of cats without ocular disease. Clinical ophthalmic and in vivo corneal confocal microscopic examinations were performed on 60 cats with keratitis. Corneal scrapings were analyzed by amoeba culture; cytological evaluation; and Acanthamoeba, Hartmannella, and Vahlkampfia PCR assays. Following ophthalmic examination, conjunctival specimens collected from 60 cats without clinically apparent ocular disease were analyzed similarly. In one cat with ulcerative keratitis, amoeba cysts and trophozoites were detected by in vivo corneal confocal microscopy; an Acanthamoeba sp. was isolated from corneal specimens and detected by Acanthamoeba PCR assay; and suppurative corneal inflammation was present cytologically. An Acanthamoeba sp. was isolated from conjunctival specimens from one cat without clinically apparent ocular disease, but with suppurative inflammation demonstrated cytologically. Both Acanthamoeba isolates belonged to the T4 genotype. Naegleria-like amoebae were isolated in samples from two cats with keratitis and seven cats without clinical ocular disease, but amoebae were not detected by the other assays in these samples. Amoeba detection by culture was significantly (P = 0.01) associated with cytologically diagnosed corneoconjunctival inflammation. This study identified naturally-acquired Acanthamoeba keratitis in cats. Detection of Naegleria-like amoebae in samples from cats with and without keratitis is of uncertain pathological significance.

Topics: Acanthamoeba; Acanthamoeba Keratitis; Amoeba; Animals; Cat Diseases; Cats; Cornea; Female; Keratitis; Male

PubMed: 34182073
DOI: 10.1016/j.tvjl.2021.105712

Review

Authors: H-S Chu, F-R Hu

Non-tuberculous mycobacteria are environmental, opportunistic pathogens that are increasingly being recognized as important causes of many human diseases. Among them, rapidly growing mycobacteria are the most notorious organisms causing infectious keratitis. Non-tuberculous mycobacterial (NTM) keratitis commonly occurs after trauma or refractive surgery, and can masquerade as fungal, herpetic or amoebic keratitis. Therefore, the diagnosis is often delayed. Prolonged medical treatment and judicious surgical debridement are required in order to eradicate the pathogens. Combination therapy with aminoglycosides, macrolides and fluoroquinolones improves the prognosis and decreases the occurrence of drug resistance. However, regardless of the development of new diagnostic techniques and antimicrobials, NTM keratitis remains a clinical challenge for most ophthalmologists. In this article, we provide a concise introduction to the epidemiological features and clinical characteristics of NTM keratitis, and the modern diagnostic tools used for it. We also summarize the current concepts of prevention and treatment for this potentially devastating condition.

Topics: Anti-Bacterial Agents; Debridement; Humans; Keratitis; Mycobacterium; Mycobacterium Infections, Nontuberculous; Surgical Wound Infection; Wounds and Injuries

PubMed: 23211011
DOI: 10.1111/1469-0691.12094

Review

Authors: Raghuram Koganti, Tejabhiram Yadavalli, Raza Ali Naqvi...

Keratitis is one of the most prevalent ocular diseases manifested by partial or total loss of vision. Amongst infectious (viz., microbes including bacteria, fungi, amebae, and viruses) and non-infectious (viz., eye trauma, chemical exposure, and ultraviolet exposure, contact lens) risk factors, viral keratitis has been demonstrated as one of the leading causes of corneal opacity. While many viruses have been shown to cause keratitis (such as rhabdoviruses, coxsackieviruses, etc.), herpesviruses are the predominant etiologic agent of viral keratitis. This chapter will summarize current knowledge on the prevalence, diagnosis, and pathobiology of viral keratitis. Virus-mediated immunomodulation of host innate and adaptive immune components is critical for viral persistence, and dysfunctional immune responses may cause destruction of ocular tissues leading to keratitis. Immunosuppressed or immunocompromised individuals may display recurring disease with pronounced severity. Early diagnosis of viral keratitis is beneficial for disease management and response to treatment. Finally, we have discussed current and emerging therapies to treat viral keratitis.

Topics: Antiviral Agents; Eye Infections, Viral; Humans; Keratitis; Prevalence

PubMed: 33556334
DOI: 10.1016/j.exer.2021.108483

Review

Authors: Manisha Acharya, Javed Hussaina Farooqui, Shikha Jain...

Infective Keratitis is a commonly encountered sight-threatening ocular emergency. In developing countries, it is a major cause of corneal blindness. Empirical treatment without microbiological work up often leads to treatment failure. Indiscriminate use of steroid antibiotic combination worsens the situation and makes further management challenging. The correct line of management can be potentially sight saving for both the ophthalmologist and the patient. This article on Infective keratitis has been written keeping best practices and protocols in mind. In a very simple and concise form, it focuses on the salient features of clinical presentation of infective keratitis and the stepwise approach to subsequent management in a patient. It explains in detail the way to perform corneal scraping, the importance of the same and further management based on microbiologically proven result. The management part includes indications and methods for medical as well as surgical intervention. We aimed to share our experience in the management of patients presenting with infective keratitis in the clinic.

Topics: Anti-Bacterial Agents; Bacteria; Cornea; Disease Management; Eye Infections, Bacterial; Global Health; Humans; Incidence; Keratitis; Risk Factors

PubMed: 31334389
DOI: No ID Found

Review

Authors: Celia García-López, Marina Rodríguez-Calvo-de-Mora, Davide Borroni...

During infectious keratitis, the production of collagenolytic and inflammatory substances, along with increased corneal matrix metalloproteinase (MMP) activity, induces the degradation of corneal collagen and may cause postkeratitis complications, such as opacity, thinning, and corneal perforation. MMPs, especially MMP-2 and MMP-9, are overexpressed in infectious keratitis and sustained over time by inflammatory and nonmicrobial mechanisms. The high MMP levels are correlated with excessive corneal destruction in bacterial, herpetic, fungal, and acanthamoeba infections. Nonspecific treatments, such as tetracyclines, particularly doxycycline, or corticosteroids, are used as adjuvants to antimicrobials to alleviate the disproportionate degradation and inflammation of the corneal layers caused by corneal MMPs and decrease the recruitment and infiltration of inflammatory cells. Treatments showing inhibition of specific MMPs (Galardin, ZHAWOC7726), interfering with pro-MMP activation (EDTA, ascorbic acid), or showing anticytokine effect (epigallocatechin-2-gallate, TRAM-34) have been reported. Other treatments show a direct action over corneal collagen structure such as corneal cross-linking or have been associated with reduction of MMP levels such as amniotic membrane grafting. Although the use of these drugs has been shown in studies to be effective in controlling inflammation, especially in experimental ones, robust studies are still needed based on randomized and randomized clinical trials to demonstrate their potential effect as adjuvants in the management of infectious keratitis.

Topics: Humans; Corneal Ulcer; Keratitis; Cornea; Inflammation; Collagen

PubMed: 37352980
DOI: 10.1016/j.survophthal.2023.06.007

Review

Authors: Venkatesh N Prajna, Lalitha Prajna, Srinivasan Muthiah...

Research becomes very significant and meaningful when it addresses a significant public health problem of a region. Fungal keratitis is a serious problem affecting the agrarian poor and hence requires attention from public health specialists. The approach to a public health issue should focus not only on treatment but also prevention or at least show a significant thrust to reduce the morbidity of the problem. At our institution, we have developed a special interest in fungal keratitis and tried to study it in a multitude of aspects. As we put the pieces of the puzzle together, we believe that interest will be rekindled among policymakers, clinicians, microbiologists, pharmaceutical industry, and basic scientists to work together to join forces and take up an integrative approach to managing this problem. It is also believed that the article underscores the need and importance of having a focused approach to ensuring a successful career in clinical research.

Topics: Biomedical Research; Eye; Eye Infections, Fungal; Fungi; Global Health; Humans; Keratitis; Morbidity; Periodicals as Topic; Public Health

PubMed: 29044053
DOI: 10.4103/ijo.IJO_821_17