Figure 1: Algorithm for clinical diagnosis of Demodex blepharitis
Two species of demodex mites, ie Demodex folliculorum and Demodex brevis, have been reported to be found in humans. The former lives in eyelash follicles and the latter burrows deep inside the meibomian glands.
Demodex mites have been implicated in causing various ocular diseases such as anterior and posterior blepharitis, blepharokeratoconjunctivitis, and are a comorbidity in dry eye disease (DED) and meibomian gland dysfunction (MGD).
The signs and symptoms of Demodex blepharitis overlap with DED and MGD. Additionally, the mere presence of Demodex may not be a reliable indicator of the disease since demodex is also found in healthy individuals.
Hence, Demodex blepharitis remains an underdiagnosed condition in clinical practice. Furthermore, due to the absence of standardised investigative and management guidelines, significant variation is seen among practitioners in how to detect and treat this condition.
What was the aim of your study?
The aim of our study was to develop a diagnostic algorithm along with management guidelines that can be used in optometric practice and education for clinical investigation of Demodex blepharitis from a consensus of expert advice.
What do the results of your study show?
Although our study did not reach a consensus on every aspect related to Demodex, certain recommendations have been proposed which might assist eye care professionals (ECPs) in tailoring their examination. These recommendations suggest that Demodex blepharitis causes tear film abnormalities and therefore is a significant cause of ocular discomfort.
This means that it is necessary to examine for Demodex blepharitis in routine clinical practice. The prevalence increases in older individuals with some studies reporting it reaching up to 100% in people older than 70 years. Therefore, the older age group is more
vulnerable. Sex does not appear to play a role in Demodex and affects both males and females equally.
Lid margin itch and grittiness are the most common symptoms. The presence of cylindrical dandruff at the base of eyelashes is a pathognomonic sign and can be easily viewed at high magnification (25x to 40x). Rosacea and age are common risk factors and DED and MGD are the most common associated conditions.
Diagnosis is confirmed based on the presenting signs and symptoms. Once confirmed, a tailored approach should be undertaken to reduce the mite numbers and resolve the signs and symptoms.
Although a number of different miticidal products were suggested by the expert panel, a consensus was reached that products containing tea tree oil (TTO) derivatives such as Blephademodex were the most appropriate first-line treatment option.
Additionally, removing cylindrical dandruff by lid hygiene techniques and then applying 5% Tea tree oil derivatives twice a day for four to six weeks would enhance its effectiveness. The life cycle of Demodex is around two weeks therefore it is necessary to review patients between two to six weeks to check the effectiveness of the ongoing treatment.
If there is an improvement in the patient’s signs and symptoms continue treatment and monitoring. If not, a more aggressive treatment regime with an increased frequency of lid cleaning with a higher concentration of TTO can be employed. However, this should be done with caution and in practice.
Figure 2: Proposed treatment algorithm for Demodex blepharitis
Why might this work be important to ECPs?
Certain ocular surface diseases share common physiological mechanisms, which result in overlapping signs and symptoms such as ocular itching, redness and reduced tear stability. This makes the diagnosis and management of the patients difficult. Furthermore, the chronic nature of this condition affects the quality of life of patients.
And in the long run, this could have a significant negative impact on their daily activities. Therefore, a proper diagnosis with a targeted treatment will help resolve this issue.
What are the limitations of the work?
High-quality research in this area is limited, and future research could bring new insights and interesting developments on the subject. There is a lot of novel research being conducted in this area with new treatment options being investigated. Therefore, the treatment recommendation from our study may get modified as new research on the subject becomes available.
What further work still needs to be undertaken in this field?
The effectiveness of other miticidal products and their safety on the ocular surface need to be addressed in the larger population.
Conclusion
Based on the theoretical knowledge and clinical experience of the expert panel, we proposed a pragmatic approach to effectively diagnose and manage Demodex blepharitis in routine clinical practice which includes appropriate magnification on the slit lamp, associated signs, symptoms, risk factors and suggested management options.
- Nikhil Sharma is a full-time lecturer at Glasgow Caledonian University. He holds a PhD in optometry and vision sciences from the same university, where his research was focused on the clinical and microbiological impact of Demodex blepharitis on ocular surface inflammation. Sharma’s ongoing research is centred around anterior eye, including blepharitis, dry eye disease, meibomian gland dysfunction, and contact lenses.
- Dr Eilidh Martin is a lecturer in Vision Sciences. Martin graduated with a BSc(Hons) degree in Optometry from GCU in 2010. She then enjoyed a period working in optometric practice before returning to complete a PhD at GCU. Martin’s PhD focused on the analysis of tear samples in patients with dry eye disease. Following the completion of this Martin undertook a post-doctoral research project looking at different management options for dry eye disease before accepting a lectureship at GCU. Martin’s undergraduate teaching focuses on contact lenses and anterior eye.
Martin’s research focuses on anterior eye and contact lenses, in particular investigating different aspects of dry eye disease and blepharitis. She is also a regional councillor for the Association of Optometrists and a member of the British University and College Contact Lens Educators (BUCCLE) - Full findings were published in: Sharma N, Martin E, Pearce EI, Hagan S. A Delphi approach to establishing consensus on best practice for the diagnosis and treatment of Demodex blepharitis. Contact Lens and Anterior Eye. 2024 Feb 1;47(1):102080.