What is an ocular mite? - briefly
An «ocular mite» is a microscopic ectoparasite, usually a Demodex species, that inhabits the eyelid margin and ocular surface. Its feeding on epithelial cells and secretions may trigger irritation, inflammation, or blepharitis.
What is an ocular mite? - in detail
Ocular mites are microscopic ectoparasites that inhabit the hair follicles and sebaceous glands of the human eyelid margin. Two species predominate in the peri‑ocular region: Demodex folliculorum, which resides primarily in lash follicles, and Demodex brevis, which colonises the meibomian glands. Adult mites measure 0.2–0.4 mm, possess a cigar‑shaped body, four pairs of legs, and lack respiratory openings, relying on diffusion through the cuticle for gas exchange.
The life cycle comprises egg, larva, protonymph, deutonymph and adult stages. Females deposit 10–30 eggs per day on the lash base; hatching occurs within 3–4 days, followed by successive molts lasting 1–2 weeks. Complete development requires 2–3 weeks, after which adults remain on the host for up to six months before dying.
Habitat and transmission
- Occupies the follicular epithelium of eyelashes and the secretory ducts of meibomian glands.
- Direct contact between individuals, especially sharing towels or cosmetics, facilitates transfer.
- Infestation prevalence increases with age, hormonal changes, and immunosuppression.
Clinical manifestations
- Mild cases produce no symptoms; heavy colonisation may cause blepharitis, itching, burning, foreign‑body sensation, and cylindrical dandruff at the lash base.
- Inflammation of the meibomian glands can lead to dry‑eye syndrome and altered tear film stability.
Diagnostic methods
- Slit‑lamp examination with high magnification reveals moving mites or characteristic debris.
- Epilation of a few lashes followed by microscopic analysis confirms species identification.
- In vivo confocal microscopy provides non‑invasive visualization of mites within follicles.
Therapeutic approaches
- Mechanical removal of lashes (eyelash trimming) reduces mite load.
- Topical agents such as tea‑tree oil (5 % formulation), ivermectin cream, or benzyl benzoate applied nightly for 4–6 weeks eradicate colonies.
- Oral ivermectin (200 µg/kg) administered as a single dose may be employed in refractory cases.
- Adjunctive lid hygiene using warm compresses and diluted baby shampoo maintains glandular function.
Prevention strategies
- Regular lid cleansing with mild, non‑irritating cleansers.
- Avoidance of shared eye cosmetics and towels.
- Periodic monitoring in patients with chronic blepharitis or dry‑eye disease.
Understanding the biology, lifecycle, and clinical impact of ocular mites enables accurate diagnosis and effective management, reducing ocular discomfort and preserving visual health.