Evaluating Therapies for Demodex Blepharitis

Demodex mites, specifically the Folliculorum and Brevis species, are one of the causes of blepharitis and can be found in a high percentage of the population, particularly in individuals over 60 years old. In a study published in Contact Lens and Anterior Eye, researchers investigate treatment approaches and their effectiveness in reducing Demodex counts.

Microscopic examination of eyelash samples can confirm the presence of Demodex mites. Various treatments were used to eradicate these mites, including tea tree oil (TTO) and its derivatives, systemic and topical ivermectin + metronidazole, and other non-TTO treatments. Studies have shown that systemic and topical ivermectin + metronidazole are particularly effective in reducing Demodex counts, while TTO-based treatments may lead to adverse reactions in some cases.

A systematic review and meta-analysis were conducted to assess the effectiveness of these treatments for Demodex blepharitis. The analysis revealed that systemic and topical ivermectin + metronidazole were the most effective in reducing Demodex counts, and pharmacological interventions generally outperformed nonpharmacological ones in achieving total eradication of mites. Adverse reactions, although mostly mild, were more likely to occur in intervention groups, especially with TTO-based treatments.

The study encompassed 8 research investigations involving 29 different treatment approaches, enrolling 1195 participants with a collective 1574 affected eyes demonstrating Demodex Spp infestations. The analysis focused on various parameters, including Demodex counts, total eradication rates, clinical improvement, Ocular Surface Disease Index (OSDI), Tear Break-Up Time, cylindrical dandruff presence, Schirmer test results, osmolarity levels, and the occurrence of adverse reactions. Stratified sub-analyses were conducted to discern specific effects.

The overall findings indicated a mean difference of -2.07 (95 % CI -3.99 to -0.15) p=0.03 for the Demodex count. Moreover, there was a risk ratio of 1.84 (95 % CI 1.27–2.66) p=0.001 for total eradication, demonstrating a significant increase in the likelihood of eliminating Demodex mites. Lastly, the risk difference for adverse reactions was 0.24 (95 % CI 0.08 to 0.41) p=0.005, denoting a higher probability of adverse reactions in the intervention groups.

Because Demodex blepharitis is a common condition with significant economic implications, the most effective treatments involve topical ivermectin + metronidazole, according to researchers. Although researchers suggest health care professions consider potential adverse reactions, "It is necessary to execute long follow-up, prospective studies to determine reinfestation rates for different therapeutic interventions, allowing profiling of long-term effects and refining therapeutic schemes in treating pathology of high frequency, such as Demodex blepharitis," said researchers.

Reference

Martínez-Pulgarín DF, Ávila MY, Rodríguez-Morales AJ. Interventions for Demodex blepharitis and their effectiveness: A systematic review and meta-analysis. Contact Lens and Anterior Eye. Published online May 2021:101453. doi:10.1016/j.clae.2021.101453