Authors: Zhang Yang, Sun Xuguang
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To analyze the signs of Demodex infection on palpebral margin and to accurately evaluate the indications of the eyelash examination for Demodex, which can provide a reliable basis for the pathogenic diagnosis.
A prospective case observational study was performed.The general status, examine results of eyelash epilation for Demodex and local clinical features of patients clinically diagnosed as Demodex blepharitis from Dececember 2015 to March 2016 at Beijing Tongren Eye Center were collected and analyzed.Logistic regression was applied to analyze the correlation between the positive rate and clinical signs.Chi-square test and Kruskal-Wallis H test were applied to compare the positive rate and the load of Demodex among patients with different clinical traits and different total number of concurrent signs.
Eighty patients (960 eyelashes) were analyzed and 857 mites were detected.The Demodex positive rate of eyelashes with non-cylindrical dandruff (46.1%) and with cylindrical dandruff (45.4%) were higher than that without dandruff (34.4%), the differences were statistically significant (both at P<0.05). Eyelashes with dilated follicular openings, white spots at infundibulum of follicle, misdirected eyelashes and telangiectasia of lid margin around eyelash had higher Demodex positive rate and Demodex load than those without above-mentioned clinical signs, the differences were statistically significant (both at P<0.01). The Demodex positive rate of eyelashes with scale was significantly lower than that without this sign (P=0.023). White spots at infundibulum of follicle and misdirected eyelashes were two major risk factors for mite detection (OR=5.588, P=0.000, OR=5.546, P=0.000). The positive rate and the load of Demodex increased as the total number of concurrent signs increased.
There are limitations in clinical diagnosis of Demodex blepharitis according to signs of cylindrical dandruff.Eyelashes with no cylindrical dandruff, white spots at infundibulum of follicle and misdirected eyelashes are three high-risk clinical indications of pathogenic examination in Demodex blepharitis.Eyelashes with higher total number of concurrent signs have high positive rate and load of Demodex during eyelash epilation.