Acanthamebic keratitis
The content of the article:
- Causes and risk factors
- Forms of the disease
- Disease stages
- Symptoms
- Features of the course of the disease in children
- Diagnostics
- Treatment
- Possible complications and consequences
- Forecast
- Prevention
Acanthamebic keratitis is an infectious inflammation of the cornea of the eyeball caused by acanthamoebas. It most often affects contact lens wearers who violate the rules for wearing and caring for them. Only in 4-5% of cases, acanthamoebic keratitis develops as a complication of traumatic eye injuries, including surgical ones.
The first outbreak of acanthamoebic keratitis was recorded in 1973; the disease then affected almost 90% of people wearing contact lenses. Studies have been carried out to find out the cause of the disease and develop reliable preventive measures. Currently, the incidence of acanthamoebic keratitis does not exceed 0.003%.
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Causes and risk factors
The causative agent of acantamobic keratitis is the simplest unicellular organism, acanthamoeba, which lives in the aquatic environment. Acanthameb can be found not only in water from artificial or natural reservoirs, but even in tap water that has passed the required cleaning and disinfection cycle.
Getting into the mucous membrane of the eyes with infected water, acanthamoebas produce a special protein that allows them to attach to the cornea. Various injuries to the cornea (for example, microtrauma resulting from the use of contact lenses) enhance the ability of acanthameb to attach to keratocytes. After attachment, acanthamoeba actively synthesize enzymes that have a destructive effect on the stroma and cells of the cornea. This process allows the pathogen to gradually penetrate into the deeper layers, causing ulceration of the cornea.
The causative agent of acanthamoeba keratitis is the unicellular organism of acanthamoeba
Risk factors for the development of the disease are:
- using tap or spring water to clean and (or) moisten contact lenses;
- storing lenses in a poorly disinfected container;
- storing lenses in solutions that are not intended for this;
- acceptance of any water procedures with contact lenses on;
- rinsing the eyes for injuries with unboiled tap water without the use of antiseptics.
Forms of the disease
The infectious and inflammatory process in the tissues of the cornea with acanthamebic keratitis has a slow chronic course and does not respond well to conservative therapy. It is extremely rare that the disease proceeds in a rapid form, in which there is a rapid destruction of the cornea.
Disease stages
Depending on the depth of the lesion of the cornea with acanthamoebas, the following stages of acanthamoebic keratitis are distinguished:
- Superficial epithelial keratitis.
- Superficial punctate keratitis.
- Stromal annular keratitis.
- Ulcerative keratitis.
- Keratoscleritis.
Symptoms
Acanthamoebic keratitis is characterized by the appearance of chemosis (pronounced edema) of the conjunctiva and severe pain in the area of the affected eye. At the same time, the intensity of the pain syndrome does not correspond to the severity of the objectively observed changes in the cornea.
Patients complain of photophobia, a feeling of a foreign body in the eye, blurred vision.
Acanthamebic keratitis is accompanied by swelling and severe pain in the eye
Features of the course of the disease in children
Due to the fact that contact vision correction is extremely rare to improve visual acuity in early childhood, acanthamoebic keratitis practically does not occur in this age group. However, if the disease nevertheless occurs, it is characterized by the following symptoms:
- pronounced swelling and redness of the conjunctiva;
- strong pain;
- photophobia.
Children suffering from acanthamoebic keratitis usually try not to open the affected eye, cover it with their palm, cry, and be capricious.
Diagnostics
Diagnosis of acanthamoebic keratitis is quite difficult, since the clinical picture of the disease is similar to many other types of keratitis, in particular with inflammation of the cornea caused by the herpes simplex virus. The diagnosis can be confirmed by bacteriological examination: acanthamoebas are found in biopsies or scrapings of the cornea after sowing the obtained material on nutrient media.
Microscopy of the corneal scraping after treatment with dyes is also performed. Immunofluorescence is also effective in this case.
Corneal microscopy and bacteriological examination for the diagnosis of acanthamoebic keratitis
Currently, molecular biological methods are often used in the diagnosis of acanthamoebic keratitis, which include polymerase chain reaction (PCR). Even a minimal amount of acanthameb can be detected by PCR in the test material.
An effective diagnostic method for acanthamoebic keratitis is confocal microscopy. This is a non-invasive, non-contact procedure that allows you to identify both the acanthamoebas themselves and their cysts in the stroma of the cornea.
Treatment
Etiotropic drugs in the treatment of acanthamoebic keratitis are cationic antiseptics, applied externally in the form of eye drops. To achieve a faster effect, a combination of cationic antiseptics with aromatic diamidines or aminoglycoside antibiotics is often used. Aminoglycosides are either used in the form of eye drops or injected subconjunctivally.
If necessary, antifungal agents of the imidazole group may be included in the treatment regimen for acanthamoebic keratitis.
For the treatment of acanthamoebic keratitis, aminoglycosides are used in the form of eye drops
The first 48 hours, instillation of eye drops is carried out hourly. Then the eye drops are used every 6 hours for several months.
To reduce the severity of pain, non-steroidal anti-inflammatory drugs are used.
Conservative treatment of acanthamoebic keratitis, especially if it was started in the late stages of the disease, does not always allow achieving a lasting positive effect and preserving visual function. In such situations, surgical treatment is required. Various surgical techniques are used:
- donor corneal transplant;
- penetrating keratoplasty;
- layer-by-layer superficial keratoplasty using a conjunctival flap;
- deep layer-by-layer keratoplasty;
- phototherapeutic keratectomy.
Possible complications and consequences
Complications of acanthamoebic keratitis are:
- secondary glaucoma;
- scleritis;
- iridocyclitis;
- perforation of the cornea.
Forecast
Acanthamebic keratitis with an unfavorable course leads to a significant deterioration in vision, up to its complete loss. To achieve its recovery in this case is possible only through surgical intervention.
Prevention
Prevention of acanthamoebic keratitis consists in strict adherence to the rules for the care of contact lenses. To moisten, disinfect and store them, use only solutions specially designed for this, and replace containers on a quarterly basis. If possible, it is better to switch to wearing daily lenses as the most hygienic and safest.
Remove contact lenses when showering or bathing, swimming in open water or swimming pools.
Contact lens wearers should regularly visit an ophthalmologist, even if they have no complaints, since routine examinations can identify possible complications of contact vision correction and timely treatment.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
