Demodex blepharitis is a chronic inflammation of the eyelid margin caused by overpopulation of mites of the genus Demodex, which normally inhabit human hair follicles and sebaceous glands. It can present as either anterior blepharitis (centered on the eyelash follicles) or posterior blepharitis (centered on the meibomian glands). Cylindrical dandruff surrounding the base of the eyelashes is a highly pathological sign and serves as a starting point for clinical diagnosis1)2).
Marginal blepharitis is a chronic inflammation of the eyelash roots and glands at the eyelid margin. It is classified into staphylococcal (ulcerative) blepharitis, seborrheic blepharitis, posterior blepharitis (MGD), and mixed types. Demodex blepharitis can overlap with any of these and has historically been recognized more as “one of the causes” rather than an independent disease.
The genus Demodex was first described by Henle in 1842, and in 1963, Post and Juhlin reported its association with human blepharitis1). The pathogenicity was debated for a long time, but epidemiological studies, immunological analyses, and treatment response evaluations since the 2000s have increasingly clarified that it is directly involved in a certain number of cases of chronic blepharitis, recurrent chalazion, and blepharokeratoconjunctivitis1)6).
There are two main species of Demodex that parasitize humans.
Both species have a life cycle of about 14–18 days, mating on the skin surface at night and growing from egg to larva to adult1).
The prevalence of Demodex infestation increases markedly with age1).
Demodex infestation is found in approximately 30–74% of patients with chronic blepharitis1). In the United States, the estimated number of patients with Demodex blepharitis is about 25 million, with 80% reporting interference with daily life, 47% having difficulty driving at night, and 34% experiencing restrictions in contact lens wear or makeup use1).
The Japanese Meibomian Gland Dysfunction Clinical Practice Guidelines 2023 include prevalence data from a population-based survey (Hirado-Takushima Study) targeting MGD, reporting rates of 21.6% in the 40s, 41.9% in the 60s, and 63.9% in the 80s4). Since MGD and Demodex overlap in pathology, it has been suggested that Demodex may be involved in a certain proportion of these elderly individuals4).
There is no internationally unified official diagnostic criteria. In Japan, diagnostic criteria as an independent disease have not been established, and clinical judgment is made within the framework of chronic blepharitis and MGD1)4).
Parasitism of Demodex is confirmed in approximately 30–74% of patients with chronic blepharitis, and it is estimated that there are about 25 million potential patients in the United States1). The parasitism rate increases with age, reaching 20–30% in the 20s, over 80% in those aged 60 and older, and nearly 100% in those aged 70 and older1). According to a population survey published in the Japanese Meibomian Gland Dysfunction Clinical Practice Guidelines 2023, the prevalence of MGD reaches 21.6% in the 40s, 41.9% in the 60s, and 63.9% in the 80s, and Demodex is thought to be involved in some of these cases4).
Typical complaints are chronic itching of the eyelid margin, burning sensation, and foreign body sensation. Itching tends to be stronger in the morning and at night, and patients often describe it as “the edge of the eye is itchy” or “the base of the eyelashes tingles”1). It may be accompanied by discharge, tearing, photophobia, and blurred vision, with symptoms recurring in cycles of remission and exacerbation.
The impact of Demodex blepharitis on patients’ QOL is not small. Reports indicate that 80% of patients experience effects on daily life, 47% have difficulty driving at night, and 34% experience restrictions on contact lens use or makeup1). Complaints such as a sensation of eyelash sticking, eyelash loss, and makeup coming off easily are also characteristic1).
Diagnosis of Demodex blepharitis is based on slit-lamp examination with a diffuser. The following findings are noted1)2)4):
Lee et al. analyzed 9 cases of Demodex blepharitis and detected D. folliculorum in all cases. Notably, the cases included children aged 5, 13, and 14 years, who presented with severe blepharokeratoconjunctivitis (BKC) accompanied by corneal ulcers and corneal neovascularization2). In recurrent childhood keratitis, involvement of Demodex should be suspected.
Zhang and Liang reported a case of a 46-year-old man. The patient presented with decreased visual acuity in the right eye for one month, and examination revealed dandruff at the eyelash roots, eyelid margin telangiectasia, meibomian gland orifice obstruction, and punctate superficial keratopathy5). Demodex was not detected in epilated eyelashes, but after antiseptic treatment of the eyelid margin, meibum was expressed and examined under a microscope, revealing 15 D. brevis organisms. Symptoms improved with eyelid hygiene using tea tree oil. This case demonstrates the existence of Demodex blepharitis in which D. brevis is present only within the meibum without external findings5).
Anterior Demodex blepharitis
Main cause: Demodex folliculorum
Characteristic findings: Cylindrical dandruff at the eyelash roots, anterior eyelid margin redness, telangiectasia, eyelash loss and misdirection
Subjective symptoms: Morning itching, prickling sensation at the eyelash roots
Detection method: Adults and larvae are easily identified by light microscopy of epilated eyelashes
Posterior Demodex blepharitis
Main cause: Demodex brevis
Characteristic findings: Meibomian gland orifice obstruction, irregular eyelid margin, migration of the mucocutaneous junction, MGD-like findings, abnormal meibum quality
Subjective symptoms: Ocular discomfort, sensation of pressure, dryness, “sticky feeling”
Detection method: Even if negative on eyelash epilation, it may be detected by direct observation of expressed meibum
Mixed/Combined Type
Features: Anterior and posterior findings coexist; the most common type in clinical practice
Associated conditions: MGD, evaporative dry eye, recurrent chalazion, recurrent corneal erosion, punctate superficial keratitis, childhood blepharokeratoconjunctivitis (BKC)
Note: Even if external findings are mild, D. brevis may be hidden in the meibum; in treatment-resistant cases, consider active detection testing
Cylindrical dandruff is a transparent to white hard scale that attaches like a collar around the base of the eyelashes1). When Demodex proliferates in the hair follicle, the host’s keratinocytes reactively hyperkeratinize, and the formed keratin adheres to the base of the eyelashes along with mite feces and debris1). Although similar in shape to collarettes seen in staphylococcal blepharitis, cylindrical dandruff is considered a finding with high specificity for Demodex infestation, and when observed, it provides a basis for actively suspecting Demodex involvement1)2).
The etiology of Demodex blepharitis is a combination of excessive Demodex infestation and the host response.
Demodex folliculorum and Demodex brevis are both ectoparasites that reside on human skin, and they are found in a certain proportion of healthy individuals1)6). The differences between the two are summarized below.
| Item | D. folliculorum | D. brevis |
|---|---|---|
| Body length | Approximately 0.3–0.4 mm | Approximately 0.2 mm |
| Main parasitic site | Hair follicles including eyelashes | Meibomian glands and Zeis glands |
| Parasitic pattern | Group infestation (multiple per follicle) | Single infestation |
| Associated disease type | Anterior blepharitis | Posterior blepharitis / MGD |
| Life cycle | Approximately 14–18 days | Approximately 14–18 days |
| Ease of detection | Easily detected in epilated eyelashes | Difficult to detect in epilated eyelashes; confirmed by meibum expression |
The following factors have been reported to be associated with Demodex overpopulation and blepharitis1)4)6):
Demodex blepharitis has a high rate of comorbidity with the following diseases1)2):
The Japanese MGD Clinical Practice Guideline 2023 cautiously states that “many points remain unclear,” while introducing histopathological reports in which Demodex folliculorum was observed within meibomian glands and epidemiological studies suggesting an association between Demodex and MGD4).
Yes. Demodex folliculorum and Demodex brevis are commensal ectoparasites on human skin, and a certain number are present in most healthy adults1). Although the infestation rate is low in young people, it increases with age, and reports indicate that almost all individuals over 70 years old have Demodex present1). It becomes pathological only when excessive infestation causes physical obstruction, inflammatory response, or ocular surface damage; the mere presence of Demodex does not signify disease1)6).
The diagnosis of Demodex blepharitis is made by combining clinical findings (especially cylindrical dandruff) with direct detection of Demodex. There are no internationally unified official diagnostic criteria yet, and comprehensive judgment including treatment response is necessary1).
Inquire about chronic itching of the eyelid margin (especially worse in the morning), foreign body sensation, madarosis, history of recurrent chalazion, presence of rosacea, and poor response to previous blepharitis treatment. Also check for use of cosmetics, contact lenses, eyelash extensions, and history of hot springs or pool use.
The Japanese Journal of Ophthalmology Meibomian Gland Dysfunction Clinical Practice Guideline 2023 recommends slit-lamp observation with a diffuser as the basis for MGD examination, and the same approach is used for Demodex-related blepharitis4).
Light microscopy of epilated eyelashes
Method: Epilate about 4 eyelashes from each upper and lower eyelid and observe under a light microscope with a coverslip. In a study by Lee et al., adult and larval D. folliculorum were identified in all 9 cases2).
Diagnostic criteria: Many reports consider 2 or more mites per 4 eyelashes as pathological1).
Limitations: D. brevis parasitizes deeper layers (meibomian glands) than hair follicles, so it may not be detected by eyelash epilation1)5).
Direct observation of meibum
Method: After antiseptic treatment of the eyelid margin, compress the tarsal plate to express meibum, collect it on a glass slide, and observe under a microscope.
Utility: Zhang and Liang detected 15 D. brevis mites in the meibum of a 46-year-old male patient who had negative eyelash epilation results5).
Indications: Refractory cases with posterior blepharitis or MGD-like findings but no Demodex detected in epilated eyelashes
In vivo confocal microscopy
Method: Use a corneal confocal microscope to non-invasively visualize mites in eyelash follicles in vivo.
Advantages: Allows repeated observation, no need for epilation
Challenges: Equipment availability and cost, standardization of evaluation are issues1)
The Japanese Ophthalmological Society Guidelines for Meibomian Gland Dysfunction 2023 consider the following tests as clinical questions4).
| Test | Purpose | Recommendation in GL |
|---|---|---|
| Meibography (infrared) | Assessment of meibomian gland dropout, shortening, and dilation | Recommended4) |
| Tear break-up time (BUT) | Assessment of tear lipid layer instability | Listed as an evaluation item4) |
| Fluorescein staining | Assessment of corneal and conjunctival epithelial damage | Recommended4) |
| Meibum expression (Shimazaki classification) | Obstructive findings in MGD diagnostic criteria | Recommended to perform4) |
| Interferometry | Quantitative evaluation of tear lipid layer | Auxiliary useful4) |
The Japanese diagnostic criteria for hyposecretory MGD require all three of the following: subjective symptoms, periorificial findings (any of vascular dilation, mucocutaneous junction migration, or lid margin irregularity), obstructive findings of the orifice (plugging), and Shimazaki classification grade 2 or higher4). Many cases of Demodex blepharitis also meet these MGD diagnostic criteria.
For treatment-resistant blepharitis, consider performing staphylococcal culture, eyelid biopsy, and Demodex detection in parallel 1).
The basic method is to epilate about 4 eyelashes from each upper and lower lid and examine them under a light microscope for adult mites and larvae 1)2). However, D. brevis may hide within the meibomian glands and may not be detected by this method 1)5). In suspicious cases, after antiseptic treatment of the eyelid margin, compress the tarsal plate to express meibum and observe directly under a microscope. In a 46-year-old male, 15 D. brevis mites were detected in meibum 5). In vivo confocal microscopy is a non-invasive method that allows observation of mites within hair follicles in living tissue, but the availability and cost of the equipment are challenges 1).
Demodex blepharitis follows a chronic course, and strong evidence for a cure is lacking. The treatment goals are reduction of mite count, disappearance of cylindrical dandruff, improvement of symptoms, control of complications (MGD, BKC, RCE, chalazion), and long-term stabilization of the ocular surface 1)4)6). Treatment is based on basic eyelid care, with a strategy of adding mite-killing agents in layers.
Warm compresses, eyelid hygiene, and meibum expression are the foundation of treatment for MGD and blepharitis in general, following the recommendations of the Japanese Ophthalmological Society’s Meibomian Gland Dysfunction Clinical Practice Guidelines 2023 4).
Tea tree oil is an essential oil extracted from Melaleuca alternifolia, and its main component, terpinen-4-ol (T4O), exerts a miticidal effect7)8). The mechanism of action is thought to be mite nerve paralysis due to acetylcholinesterase inhibition1)6).
The Japanese MGD Clinical Practice Guideline 2023 also includes one RCT using a tea tree oil-containing cleansing agent, showing improvement in subjective symptoms, meibomian gland orifice findings, meibum grade, BUT, and keratoconjunctival epithelial damage4). However, the same guideline also notes that 52.5% (21 of 40 cases) in the TTO-containing cleansing agent group experienced eye irritation as an adverse event, emphasizing the importance of adjusting concentration and frequency and checking for a history of skin sensitivity when using it4).
Pharmacotherapy
Oral ivermectin: A regimen of 200 μg/kg administered twice on Day 0 and Day 7 is used9). In a study of 24 eyes of 12 patients with refractory posterior blepharitis, a significant decrease in D. folliculorum count, improvement in Schirmer I value, and improvement in BUT were reported9). It induces paralysis by acting on mite GABA receptors1).
Topical ivermectin cream 1%: The miticidal and anti-inflammatory effects are enhanced when combined with metronidazole1).
Metronidazole: It has both DNA damage via nitro radicals and anti-inflammatory effects, and is used orally or topically1).
0.25% povidone-iodine / DMSO formulation: Topical application twice daily has been reported in case reports to improve symptoms and signs of anterior and posterior Demodex blepharitis11).
1.5% azithromycin hydrate ophthalmic solution: Weakly recommended in the MGD guidelines for improving subjective symptoms, meibomian gland orifice findings, and meibum grade4).
0.1% fluorometholone ophthalmic solution: Short-term use in cases with severe inflammation. Weakly recommended in the MGD guidelines; in Japan, insurance coverage is limited to cases with blepharitis4).
Minocycline hydrochloride 100 mg/day oral: Used as part of standard MGD treatment for anti-inflammatory and lipid-modulating effects4).
Mechanical and Physical Therapies
Microblepharoexfoliation (BlephEx): An office procedure that mechanically removes cylindrical scales, debris, and mites from the eyelid margin using a rotating microsponge1). It is also expected to disrupt bacterial biofilms, and combination with tea tree oil therapy has been reported to improve OSDI and mite counts1).
Meibomian gland probing: Improves meibum expression in Demodex blepharitis complicated by obstructive MGD6).
LipiFlow® thermal pulsation: A 12-minute procedure combining internal heating and external compression, reported to improve meibum secretion, TBUT, and subjective symptoms6).
IPL (Intense Pulsed Light) therapy: Kills mites through thermal effects of broadband light (rising to approximately 49°C in vitro). Reduction of meibomian gland vascular dilation, decreased mite counts, and improvement of subjective symptoms have been reported1). In the Japanese MGD Clinical Practice Guidelines 2023, the evidence is strong, but it is only “weakly recommended” because it is not approved as a medical device and not covered by insurance in Japan4).
| Treatment | Mechanism of Action | Typical Regimen | Notes |
|---|---|---|---|
| Tea tree oil (T4O) | AChE inhibition, direct miticidal effect1)8) | 50% once weekly + 10% daily for 1 month7)10) | Ocular irritation reported in 52.5%4) |
| Oral ivermectin | GABA receptor inhibition1) | 200 μg/kg on Day 0, Day 79) | For severe/refractory cases |
| Topical ivermectin + metronidazole | Miticidal + DNA damage1) | Apply daily1) | Useful in cases with rosacea |
| 0.25% povidone-iodine/DMSO | Oxidative and anti-mite action11) | Apply twice daily11) | Case report level |
| BlephEx | Mechanical removal1) | Outpatient procedure + home care | Enhanced effect when combined with TTO |
| IPL | Photothermal effect, miticidal 1) | 3–4 sessions at 2–4 week intervals 1) | Not approved in Japan 4) |
The basics are three steps: warm compresses, eyelid massage, and eyelid hygiene 4)6). Apply a clean towel or a commercially available warm eye mask to the eyelids for at least 5 minutes twice a day 4). Then gently massage the upper and lower eyelids in a vertical direction to promote meibomian gland secretion. Finally, carefully clean the eyelash roots with a cotton ball moistened with water or a dedicated cleansing agent 4). Preparations containing tea tree oil have been reported to be added about once a week, with attention to concentration 7)10). Avoid excessive rubbing, and pay attention to hygiene of cosmetics and eyelash extensions. Daily continuation even after the acute phase subsides is key to preventing recurrence.
The pathophysiology of Demodex blepharitis is organized through multiple pathways: mechanical mechanisms, immunological mechanisms, bacterial vector hypothesis, and overlap with MGD pathology 1)4)6).
1. Physical mechanisms
Demodex folliculorum aggregates in multiple eyelash follicles and feeds on basal keratinocytes1)6). This causes local cell damage and reactive hyperkeratosis, and the formed keratin accumulates at the base of the eyelashes together with mite feces and debris, forming cylindrical dandruff1). Chronic inflammation around the follicle contributes to eyelash loss, misdirection, and follicle destruction.
On the other hand, Demodex brevis parasitizes singly within the ducts of the meibomian glands and Zeis glands, physically obstructing the gland lumen1)5)6). Histologically, granulomatous reactions, acinar atrophy, and qualitative and quantitative decreases in lipid secretion are observed, presenting MGD-like clinical findings and chalazion-like changes5)6). In the case of Zhang and Liang, 15 D. brevis were detected in the meibum of a 46-year-old man with meibomian gland orifice obstruction, telangiectasia, and superficial keratopathy, indicating the existence of cases where parasites lurk within the glands even when external findings are mild5).
2. Immunological mechanisms
Demodex excreta, secretions, and carcasses induce a delayed-type hypersensitivity reaction in the host1). This reaction is particularly pronounced in rosacea patients and is thought to explain the high comorbidity rate of ocular rosacea and Demodex blepharitis1).
In the tear cytokine profile, increases in IL-1β, IL-17, and MMP-9 have been reported, and decreases in these cytokines have been confirmed after tea tree oil treatment6). Upregulation of Toll-like receptor 2 (TLR2) has also been reported, suggesting inflammation amplification via the innate immune pathway1).
3. Bacterial vector hypothesis
It has been suggested that bacteria adhering to the surface or gastrointestinal tract of Demodex may act as independent inflammatory triggers1)6). Candidate bacteria include Bacillus oleronius, Staphylococcus aureus, Acinetobacter baumannii, and Streptococcus pneumoniae, and the hypothesis is that host immune responses to these antigens exacerbate chronic inflammation of the ocular surface1). In rosacea patients, serum reactivity to B. oleronius antigens has been reported to be significantly higher than in healthy individuals1).
4. Overlap with MGD pathophysiology
The Japanese Ophthalmological Society Guidelines for Meibomian Gland Dysfunction 2023 propose two core mechanisms for the pathophysiology of hyposecretory MGD4): obstruction of the meibomian gland orifice due to hyperkeratinization of the ductal epithelium, and abnormal differentiation, acinar atrophy, and decreased meibum quality due to changes in meibocytes4). The guidelines list aging, sex hormones (androgens), bacterial infection, Demodex, inflammation/allergy, neural factors, vascular factors, medications, and incomplete blinking as upstream factors4).
Therefore, Demodex blepharitis adds physicochemical stress to the ducts and acini at the entrance of the MGD pathological cascade, promoting the progression of MGD. In clinical practice, Demodex blepharitis and MGD exacerbate each other, so it is a principle to treat both simultaneously4)6).
5. Relationship with Rosacea
In patients with cutaneous rosacea, Demodex density increases several times that of healthy individuals1). Rosacea treatments such as oral doxycycline and topical ivermectin can simultaneously improve Demodex density and ocular symptoms1). Therefore, when evaluating chronic, treatment-resistant Demodex blepharitis, it is useful to collaborate with a dermatologist to assess systemic rosacea.
Lotilaner is an isoxazoline antiparasitic drug that specifically inhibits GABA-gated chloride channels and glutamate-gated chloride channels in mites, inducing spastic paralysis and killing them1)3). Because these channels have low sensitivity in mammalian hosts, its safety profile is favorable3).
The Phase 3 pivotal trial Saturn-1 was a randomized, vehicle-controlled, double-blind study involving 421 patients with Demodex blepharitis. Treatment with Lotilaner ophthalmic solution 0.25% twice daily for 6 weeks achieved a cylindrical dandruff resolution rate of 56%, a mite eradication rate (0-1 mites per 4 lashes) of 51.8%, and an eyelid margin erythema resolution rate of 31.1%3). Tolerability was rated as good in 90.7% of patients, and side effects were mainly mild, such as burning sensation and mild visual acuity decrease1)3). Subsequent Saturn-2 trial confirmed similar results1).
In July 2023, the US FDA approved Lotilaner ophthalmic solution 0.25% (brand name XDEMVY®, formerly TP-03) as the first approved drug for Demodex blepharitis1). Approval in Europe is expected around 20271). As of 2026, it is not yet approved in Japan, and the status of application and review by PMDA requires close monitoring1).
Czepińska-Myszura et al. stated in a review article that “among new treatments, only Lotilaner ophthalmic solution has demonstrated high efficacy in large-scale clinical trials, while IPL and microblepharoexfoliation have only been validated in limited patient groups”1).
BlephEx is an in-office procedure that uses a rotating microsponge to mechanically remove cylindrical dandruff, debris, mites, and bacterial biofilm from the eyelid margin1). Combined with tea tree oil therapy, significant improvements in OSDI and mite count have been reported, but further research is needed to verify long-term efficacy and recurrence prevention1).
The acaricidal activity of natural essential oils has been reported successively1).
All of these are still at the preliminary research stage, and further validation is needed for clinical application1).
In vivo confocal microscopy (IVCM) can non-invasively visualize mites within hair follicles and allows repeated assessments1). In the future, if PCR-based molecular detection and automated image analysis are applied clinically, standardized quantitative evaluation of Demodex will become possible.
In the analysis of 9 cases by Lee et al., pediatric cases aged 5, 13, and 14 years were included, and all presented as blepharokeratoconjunctivitis with corneal ulcers and neovascularization 2). In recurrent keratitis in children, the involvement of Demodex should be strongly suspected 2).
Furthermore, Zhang and Liang reported a 46-year-old male case in whom D. brevis was hidden only in the meibum without external findings, indicating that direct observation of meibum after eyelid margin cleaning contributes to diagnosis in refractory cases 5).
As of 2026, Lotilaner ophthalmic solution 0.25% (XDEMVY®) is approved by the US FDA, but not yet approved in Japan or Europe 1)3). Approval in Europe is expected around 2027 1). The approval status in Japan depends on future PMDA review. Currently, treatment mainly includes tea tree oil-containing preparations, ivermectin (oral and topical), metronidazole, and microblepharoexfoliation 1)6).
