A Look at the Impact, Prevalence of Demodex Blepharitis

Blepharitis is characterized as inflammation of the eyelids which can cause redness, ocular irritation, and dandruff and affect skin, eyelashes, and the sebaceous glands.^1-3 According to a survey² in 2009, about one-third of patients treated by an ophthalmologist and more than 50% of patients seen by an optometrist presented signs of blepharitis.

Blepharitis can stem from a number of existing causes including excess bacteria at the base of a person’s eyelashes and issues with oil glands. Patients may report symptoms such as itching, burning, foreign body sensation, crusting or matted lashes, tearing, blurry vision, ocular discomfort, and irritation.^1-4

One of the most common and often overlooked causes of blepharitis is an infestation of microscopic Demodex mites, an ectoparasite found in humans, which can live within eyelash follicles. Demodex blepharitis affects approximately 25 million eye care patients in the United States.^1,2

There are 2 types⁴ of Demodex mites that affect human eyes, Demodex folliculorum and Demodex brevis, which have been shown to cause anterior and posterior blepharitis, blepharoconjunctivitis, blepharokeratitis, and other conditions. D folliculorum are the larger of the two and are often found at the base of the lashes. D brevis tend to inhabit the sebaceous glands.

Irritation from Demodex stems from the mites’ lack of internal digestion and excretory organs. Demodex mites “excrete proteases and lipases for external digestion of the eyelid’s healthy epithelial cells and sebum” which results in inflamed follicles and a buildup at the base of the lashes called collarettes, or cylindrical dandruff.²

Results of a previous study assessing 55 clinical cases demonstrated⁶ patients presenting with cylindrical dandruff often have a high prevalence of Demodex infestation.

“Historically, definitive diagnosis of Demodex infestation has typically been accomplished by visualization of the mites during microscopic evaluation of epilated eyelashes,” Trattler and colleagues² explain. “However, this technique is impractical as it is uncomfortable for patients, time consuming for the clinician, and not available to practices that lack access to light microscopy.”

According to results of a retrospective study² published in Clinical Ophthalmology, “Of the 4 most common reasons for an eye care visit, [researchers] found that between 54% and 65% of patients making those visits had collarettes, the pathognomonic sign of Demodex blepharitis.”

Researchers² found Demodex blepharitis was common across all ages, race/ethnicities, and genders, but more than 50% of patients presenting with collarettes had never been diagnosed with Demodex blepharitis.

At present, there are no FDA-approved treatments for D blepharitis; however, if left untreated or poorly managed, Demodex can continue to cause redness/irritation and lead to more serious corneal conditions, prompting the need for improved screening and diagnosis.^2,4

The goal of any management option is to reduce inflammation and decrease parasitic overpopulation.⁴ Symptom management options are limited but have included warm compresses, eyelid scrubs, antibiotics, eye drops, improving skin/eyelid hygiene, and fish oil.¹ Some patients report using tea tree oil eyelid products, which Trattler and colleagues² note has a poor tolerance rate, low efficacy, and is not FDA-approved. In fact, the small percentage of patients in their analysis (51 of 1031, 4.9%) who reported using tea tree oil were more likely to have Demodex when compared with those who were not using tea tree oil (74.5% vs 56.7%; P = .014).

Trattler and colleagues note their findings were limited by the retrospective study design and recommend a prospective study with more regularity of age groups to further categorize and understand the prevalence of Demodex blepharitis.

A potential treatment option targeting the nervous system of the mites is currently undergoing phase 2/3 trials. Early data shows the agent TP-03, administered daily for 4 weeks, reduced mite numbers and was also well tolerated.³

As part of a multicenter, observational, prospective, IRB-approved study,⁷ researchers found Demodex blepharitis significantly negatively impacts patients’ daily activities as well as quality of life.

Of 311 study participants aged ≥18 years, more than 50% reported experiencing blepharitis symptoms for 4 or more years. About 47% admitted they were conscious of their eyes all day and 23% expressed constant worry about their eyes. The most common treatment options were artificial tears (47%), warm compress (32%), and lid wipes (14%).⁷

“These patients allocate time and resources to health care appointments and approaches that often do not resolve their symptoms, contributing to individual and health care system costs,” concluded O’Dell and colleages.⁷

To date, no economic burden research related to Demodex blepharitis has been published; however, due to its extensive burden and unmet need, individual patient costs and costs to the health care system could be substantial.