Ocular demodicosis is a pathology caused by parasitization of a conditionally pathogenic tick of the genus Demodex – acne gland. Clinically, the disease is manifested by itching, hyperemia of the eyelids, loss of eyelashes, accumulation of purulent masses in the corners of the eyes mainly in the morning. Diagnosis of demodecosis includes microscopic examination, biopsy followed by histology, “scotch samples” and preparation of an acarogram. Biomicroscopy of the eye is used to detect secondary changes. Treatment tactics are based on the use of topical glucocorticosteroids, dermatotropic and antibacterial agents.
Ocular demodicosis or demodecosis blepharitis is a chronic disease with seasonal exacerbations in the autumn-spring period. Pathology is more often registered in the elderly, which is associated with higher sebum production than in children. Isolated cases of detection of acne gland in newborns are described. A number of studies indicate that Demodex ticks can be isolated in 89% of people under the age of 61. According to statistics, 60-70% of patients with demodectic blepharitis are diagnosed with demodicosis of other localizations. Pathology is more common in women. Geographical features of the spread of the disease have not been established.
The main etiological factor of demodecosis is the colonization of hair follicles, sebaceous and meibomian glands by a tick of the genus Demodex in the amount of at least 5 acne glands per cm2. The sources of infection are pets, a sick person or a carrier. The addition of an infectious agent (Bacillus oleronius) contributes to the development of clinical manifestations, which, as a result of its vital activity and reproduction processes, increases the activity of ticks and other microorganisms of the group of streptococci, staphylococci, propionic acid bacteria and fungi of the genus malassesia. An increased tendency to ocular demodicosis is observed in people with immunodeficiency conditions (AIDS, acute lymphoblastic leukemia, malignant neoplasms) and diseases accompanied by metabolic disorders (diabetes mellitus) in the anamnesis. Risk factors for the development of pathology – ametropia, uncorrected hypermetropia.
The triggering factor of the occurrence of ocular demodicosis is a violation of the microflora of the skin. A decrease in the secretory ability of the glands leads to a change in microbiocenosis, followed by the appearance of skin dysbiosis. A change in the qualitative characteristics of the surface lipid layer leads to an increase in microbial colonization. An important role in the pathogenesis of the disease is played by a violation of the symbiosis of corynebacteria and conditionally pathogenic microflora. The development of the clinical picture is facilitated by viruses and microorganisms, the carrier of which is the acne gland.
A tick measuring 0.2-0.5 mm penetrates into the thickness of hair follicles, sebaceous and meibomian glands. When pathogenic forms of pyococci are introduced into the deep layers, inflammation occurs, subsequently leading to purulent-necrotic changes. Maintaining the activity of the inflammatory process is provided by a violation of the synthesis of cathelicidins. The products of the tick’s vital activity lead to allergization and can cause seborrhea. Studies are being conducted on the effect of cytokine cascade disorders on tick invasion, maintenance of the pathological process and the effectiveness of the treatment used.
Demodectic blepharitis is characterized by a tendency to chronicity. In rare cases, the disease becomes acute. From a clinical point of view , the following forms of demodecosis are distinguished in ophthalmology:
Primary. In this variant, demodecosis is an independent nosology, acts as a trigger factor for the attachment of pathogenic microflora and the development of concomitant diseases.
Secondary. Pathology occurs against the background of the underlying disease of the eyelids (chronic blepharitis, rosacea or seborrheic dermatitis).
Symptoms occur against the background of general well-being. Patients have a subjective sensation of burning, bursting, crawling. The clinical picture of demodecosis is dominated by pronounced itching, swelling and hyperemia of the edges of the eyelids. A specific manifestation of pathology is a symptom of a “collar” around the eyelashes. Many patients note the feeling of a foreign body or “sand” in their eyes. The reproduction of the glands in the thickness of the sebaceous glands adjacent to the eyelashes leads to multiple loss of eyelashes. The intensive progression of pathology and the addition of pathogenic microflora is evidenced by the appearance of scales at the root of the eyelashes, purulent sticky masses along the edge of the eyelids.
Patients complain of rapid eye fatigue when performing visual work. In the initial stages of demodecosis, the skin of the eyelid becomes thinner. In the future, due to a decrease in elasticity, there is a feeling of tightening, the skin becomes thickened. Hyperkeratosis phenomena are increasing. Severe itching leads to the formation of scratching, small areas of hemorrhage, in the area of which bloody-purulent crusts are subsequently formed. Demodecosis is characterized by a high degree of invasiveness, so the disease is often diagnosed in several family members.
Demodecosis of the eyelids can be complicated by recurrent acne and psoriasis. Patients have a history of frequent purulent inflammation of the eyelash hair follicles. The etiological role of the Demodex tick in the development of chronic forms of blepharitis and blepharoconjunctivitis has been proved. Pathology is prone to frequent recurrence caused by repeated self-infection of the patient. The disease often spreads to the surrounding tissues (nasolabial folds, forehead, chin, temporal and parotid areas). The addition of pyococcal infection in patients with demodecosis of the eyelids contributes to the formation of microabcesses with subsequent formation of scar deformities.
Diagnosis of ocular demodicosis requires physical examination, laboratory verification and ophthalmological examination. On external examination, purulent masses and dry scales along the edge of the eyelids are visualized. Eyelashes are stuck together, surrounded by dry crusts. Biomicroscopy of the eye is used to study the condition of the eyelids, conjunctiva and cornea in order to diagnose secondary changes. For laboratory verification of demodectic blepharitis, ophthalmologists use:
- Microscopic examination. This is the only method that allows you to identify a tick in the thickness of the follicle. After placing the material on a slide, it is studied in detail under a microscope.
- Drawing up an acarogram. The purpose of the study is to count the number of larvae, nymphs, eggs and imagos. The detection of more than 5 adults per 1 cm2 indicates tick activity. The detection of 1 tick on 2-4 eyelashes is considered a normal indicator.
- Puncture or excision biopsy. The techniques are used to detect acne gland in the meibomian and sebaceous glands, followed by histological examination.
“Scotch test”. The study is prescribed for multiple purulent-necrotic masses on the periphery of the eyelids.
Treatment of ocular demodicosis
Treatment of demodecosis requires strict adherence to the rules of personal hygiene due to the high risk of repeated self-infection. The daily use of warm compresses on the eyelids, which have a cleansing, antiseptic and anti-inflammatory effect, is shown. The patient should independently perform circular eyelid massage in order to improve the outflow of the secretion of the meibomian glands, uniform distribution of the tear film and cleansing of the conjunctival cavity. Etiotropic therapy of ocular demodicosis includes the use of:
- Dermatotropic agents. It is used topically in the form of an ointment or cream, which includes highly purified native glycans and natural ingredients with anti-inflammatory effect (chamomile extract, olive oil).
- Antibacterial drugs. Instillations with a short course are shown in the case of attachment of microbial flora. Systemic antibacterial therapy is recommended for generalized lesions.
- Topical glucocorticosteroids. They are used in the complicated course of the disease in order to eliminate allergic manifestations and relief of local manifestations.
Symptomatic therapy requires the elimination of immunological and metabolic disorders. Optical correction of ametropia and hypermetropia is performed. Local physiotherapy involves the appointment of electrophoresis with anti-inflammatory and antihistamines. The effectiveness of cryotherapy in combination with antibacterial drugs in the treatment of patients with resistant and recurrent forms of the disease is being studied.
Prognosis and prevention
The prognosis for life and working capacity with demodicosis of the eyelid is favorable. Timely treatment ensures rapid recovery and prevents the development of complications. Specific preventive measures of ocular demodicosis have not been developed. Non-specific prevention includes: regular ironing of pillowcases and towels, sanitary treatment of shaving appliances and glasses, cleaning of personal items in contact with the skin of the face (scarves, motorcycle helmets), disposal of cosmetics contaminated with ticks.