Abstract:

Objective To analyze the diagnostic efficiency and reproducibility of modified Coston method, and to compare the detection characteristics of conventional Coston method and modified Coston method in demodex blepharitis patients. Design Diagnostic technique evaluation. Participates 131 patients visiting Beijing Tongren Eye Center, suspected of demodex blepharitis, were continuously collecting in 2018. Methods One eyelash at each of the three positions (medial, central, and lateral side) of palpebral margin from each eyelid (selecting the eyelash closest to the orifice of the meibomian gland) were sampled by both conventional and modified  Coston method. The conventional Coston method was to pull out the eyelashes directly, while the modified Coston method was a spiral pull-out manipulation rotating around the hair follicle. After the eyelashes were removed, the microscopic examination was performed and the total number of demodex of different stages were calculated. From January to July, 78 patients were collected for comparing the detection characteristics between conventional and modified method. 53 patients from August to December were collected for analysis of reproducibility of the modified Coston method. All lashes were sampled by a technician with relevant experience. SPPS 20.0 was applied for descriptive statistics of various parameters, comparing positive rate and detection amount, and calculating intraclass correlation coefficient (ICC) value; R language software was applied to compare area under curve (AUC) values of different sampling combinations. Main Outcome Measures ICC, AUC, positive rate, detection rate and detection amount of demodex folliculorum. Results The ICC of modified method was 0.874, AUC was 0.944. There was no statistically significant difference between the AUC values of sampling of central and lateral sides and that of sampling 3-5 lashes (P<0.05), and the former was most reproducible (ICC=0.897). The positive rate and total detection amount of modified method (82.1%, 499.7 mites) were higher than that of conventional method (66.7%, 437.28 mites) (P=0.028，0.000). Conclusion The modified Coston method of rotating manipulation before epilation with better repeatability can increase the detection rate of demodex. Simplified sampling combination of 2 lashes from central and lateral sides per eyelid had similar diagnostic performance compared with 3 lashes sampled in traditional Coston method.

Key words: blepharitis, demodex, Coston method