Fungal keratitis

Description:

Fungal keratitis is for the first time described by Leber in 1979. This microorganism is not the typical reason of an inflammation of a cornea, but in the tropical countries represents a huge problem. It is worth remembering a possible fungal etiology of diseases of an eye as in case of untimely diagnosis and effective treatment irreparable destructions of a cornea develop.
Fungal keratitis – the combining term for all inflammatory diseases of a cornea caused by above-mentioned microorganisms. Fungi can infect, and, so and to cause an inflammation of an enveloping layer of an eye. One of activators is the sort фузариум (Fusarium), the causing so-called fuzariumny keratitis.

Fungal keratitis throws down a diagnostic and therapeutic challenge to the ophthalmologist. Difficulties arise at diagnosis, isolation of the activator in laboratory, effective treatment by topical (local) anti-fungal means. Unfortunately, in most cases the diagnosis is exposed too late, generally because of insufficient vigilance of rather fungus diseases of eyes. But even in case of timely diagnosis treatment is difficult process in connection with insufficient permeability of a cornea  and the limited commercial access of antifungal means.

Besides, incidence of a fungal keratitis grew for the last 30 years. Prevalence of this disease grew in connection with broad use of topical corticosteroids and antibacterial agents at treatment of other types of a keratitis, increase in number of persons with the weakened immune system, improvement of laboratory diagnosis of this disease.

Symptoms of the Fungal keratitis:

Clinical diagnosis of a fungal keratitis is based on the analysis of risk factors and assessment of a condition of a cornea.

The most frequent signs of a fungal keratitis at inspection by means of a slit lamp are:
conjunctival injections
defect of an epithelium
suppuration
stroma infections
reaction of an anterior chamber
hypopyon

Carry infiltrate with the raised plumose edges, uneven texture, gray-brown pigmentation, adjacent damages, hypopyon and endothelial plaques to specific factors of a fungal keratitis.

- graceful or rough granulyatsionny infiltrate of an epithelium and front stroma
- gray-brown color, an uneven surface which can be raised
- usually uneven infiltrate with plumose edges
- a white roundish plaque on a cornea and adjacent damages near edge of primary center of an infection

Reasons of the Fungal keratitis:

Aspergilla are the most widespread activators of a fungal keratitis worldwide. Anyway, the epidemiology of this disease is connected with features of climate. In southern latitudes fuzariozny defeats, especially in the State of Florida prevail. On the contrary, in northern latitudes a candidosis and aspergillosis keratitis prevails.

To risks of a fungal keratitis carry to the most widespread factors:
Injury (for example, carrying contact lenses, hit of third-party objects). According to incidence researches in the southern Florida (USA), in 44% of cases the injury of natural character (leaves and branches) is the reason of diseases.
Use of topical corticosteroids
Surgical interventions on a cornea, for example, a through keratoplasty, seamless operation on a cornea at a cataract, laser treatment of a keratomillez (LASIK).
Chronic keratitis in connection with a virus of a herpes simplex, shingles or a spring keratoconjunctivitis
Young healthy men without essential eye diseases
In recent time injury of an eye (outdoors)
Agricultural employment  

Risk factors of a candidosis keratitis is the following:
Patients of advanced age
The previous diseases of eyes
Influence of diseases of a cornea
Chronic keratitis
Prolonged use of steroids
The diseases oppressing immune system

Treatment of the Fungal keratitis:

Antifungal drugs are classified as follows:

Carry to polyenes натамицин, nystatin, афмотерицин B. These drugs are effective against filamentous and barmy mushrooms, make the destroying action  concerning fungi as build in ergosterol a cell wall.

Amphotericinum of B – choice drug for treatment of patients with the fungal keratitis caused by yeast.

As polyenes badly pass through eye tissues, deep-permeable Amphotericinum of B more than others is suitable for treatment of a fungal keratitis of a candidosis origin. Besides, this medicine is effective concerning a set of mitseliarny mushrooms. Apply Amphotericinum of B according to the following scheme: the first days each 30 minutes, the second – each hour, and further slowly reduce frequency rate of introduction, proceeding from the clinical response to treatment.

Natamitsin has a wide range of activity of rather filamentous fungi. Penetrability of Amphotericinum of B at topical administration is a little lower, than at a natamitsin through the unimpaired epithelium of a cornea.

Natamitsin – the only commercially available local medicine from fungus diseases of eyes. This means of effectively rather filamentous fungi, especially sorts Fuzirium. In connection with weak permeability in internal structures of an eye it is generally applied against superficial infections.

Azoles (imidazoles and triazoles) include кетоконазол, Miconazolum, флуконазол, интраконазол, эконазол, Clotrimazolum. Drugs of this group oppress synthesis of ergosterol at small concentration, and at considerable show the direct destroying action on walls of cells.

Oral (applied internally) флуконазол and кетоконазол are soaked up systemically and are found in high concentration in an anterior chamber of an eye and a cornea therefore are applied at a deep fungal keratitis.

Imidazoles and triazoles are synthetic chemical antifungal means. High levels of a ketokonazol and flukonazol in a cornea were found at researches on animals. Due to the excellent permeability in eye tissue these drugs are used systemically at the keratitis caused by filamentous and barmy mushrooms.

Subconjunctival injections will be required to patients with a heavy keratitis and a keratoscleritis, and also in case of the insufficient response to the applied treatment.

Oral forms (кетоконазол and флуконазол) are recommended to be accepted to patients with deep infections of a stroma. Antifungal treatment is usually applied for 12 weeks under fixed control.

Successful antifungal treatment at a keratitis demands frequent administration of drug a long span (at least 12 weeks).

Carry to signs of overdose (toxicity) of treatment:
- The epithelial ulcerations which dragged on in time
- The expressed cornea epithelium erosion
- Diffusion defeat of a stroma