The Dry Eye Zone

Rebecca's Blog

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Study: Demodex loads in chronic blepharitis

I really appreciated this Demodex update from Turkey. This is a good reminder that if you are suffering from stubborn recurring blepharitis, make sure your assessment includes being checked for heavy Demodex mite loads and if so, that your treatment addresses that specific issue. 

In this study, they found that (1) Demodex were much more common in people who have blepharitis than people who don't, and (2) symptom scores - that is, itching, foreign body sensation and redness were more common in people who tested positive for Demodex.

J Med Entomol. 2018 Aug 17. doi: 10.1093/jme/tjy143. [Epub ahead of print]
Prevalence and Load of Demodex folliculorum and Demodex brevis (Acari: Demodicidae) in Patients With Chronic Blepharitis in the Province of Erzincan, Turkey.
Zeytun E, Karakurt Y.


Abstract
Chronic blepharitis is an ocular disease frequently encountered by ophthalmologists. Demodex mites can play a role in the pathogenesis of blepharitis along with bacterial agents, especially in treatment-resistant cases or recurrent cases after treatment. This study was performed to determine the prevalence and load of Demodex folliculorum (Simon) and Demodex brevis Akbulutova in chronic blepharitis patients and to assess the relationship between the prevalence and load of Demodex species and ocular symptoms. The study included 365 patients diagnosed with chronic blepharitis in clinical examination, and 175 controls without any chronic or ocular disease. In the study, two eyelashes were sampled from the lower and upper lids of the right and left eyes (a total of eight samples) of the participants. Eyelash samples were examined under a light microscope, and Demodex species were identified and counted. Demodex were detected in 79.2% (95% CI: 75-83%) of patients and 31.4% (95% CI: 24-38%) of controls in this study. D. folliculorum alone (mean: 4.96; min: 1; max: 17; P < 0.001) was detected in 72.3% of patients, in 0.7% D. brevis alone (mean: 1.00, P > 0.05), and in 27% both D. folliculorum and D. brevis (mean: 21.65; min: 2; max: 79; P < 0.001). In Demodex positive controls, only D. folliculorum (mean: 2.38; min: 1; max: 6) was detected while there was no D. brevis. Nevertheless, mean ocular symptom scores were significantly higher in Demodex positive patients than in Demodex negative patients (P < 0.001). Itching, foreign body sensation, and redness were the most common complaints in Demodex positive patients. As a result, Demodex mites were high in numbers in patients with chronic blepharitis in Erzincan. There was a positive correlation between Demodex mites and chronic blepharitis and ocular symptoms. It may be helpful to consider these findings in clinical assessment of blepharitis patients.