The Prevalence Of Ocular Demodex Folliculorum In The Different Eyes And Eyelid Margins In Healthy Young Males

ObjectiveTo explore the prevalence of Demodex folliculorum in the different eyes and eyelid margins in healthy young males,and further analyze the influencing factors of Demodex folliculorum,and evaluate the relationship between the number of Demodex folliculorum and ocular surface symptoms,which may reveal the prevalence characteristics of ocular Demodex folliculorum in healthy young males,and provide clinical basis for the examination method of Demodex folliculorum in eyelashes.MethodsA cross-sectional study was adopted.In September 2020,3423 male recruits in the18-24 age range(average age 20.38±1.72)in Fujian Province assigned to the 900 th Hospital of PLA were screened by questionnaires about personal details and ophthalmic examinations.All of them were randomly divided into three groups by the edge of the eyelid: internal,median and external.According to different groups,2 eyelashes were taken from each eyelid from each upper eyelid,and 4 for each person.Search and count the Demodex folliculorum under the optical microscope.The sample was defined as positive if at least one Demodex folliculorum were present.The differences of ages among different groups were compared with analysis of variance;the differences of the detection degree of Demodex folliculorum were compared with analysis of KruskalWallis test.The chi-square test was used to evaluate the differences of baseline data and the detection rate of Demodex folliculorum among different groups.Binary logistic regression was used to evaluate the influencing factors of Demodex folliculorum.Spearman correlation analysis was used to evaluate the correlation between the number of Demodex folliculorum and ocular surface symptoms.Results1.In this research,451 males in 3423 samples were positive for Demodex folliculorum,with a detection rate of 13.18%(451/3423).895 mites were found,with a detection degree of 0.50(0.25,0.75)/per eyelash.2.The positive rate of Demodex folliculorum in the group with a history of myopia correction surgery had a statistically significant increase than the group without ocluar surgery(P<0.001).The positive rate of Demodex folliculorum in subjects with ocular symptom was higher than that in the asymptomatic group(P=0.044).The different long-term residence,smoke and drinking habits,facial skin type and acne had no significant influence on the detection rate of Demodex folliculorum(all P>0.05).3.The positive rate for Demodex folliculorum in different eyes: right upper eyelid7.92%(271/3423)vs.left upper eyelid 7.27%(249/3423),and there was no significant difference(P>0.05).4.The positive rate for Demodex folliculorum in different eyelid margins: internal14.17%(195/1190)vs.median 16.39%(162/1143)vs.external 8.62%(94/1090),and the difference was statistically significant(P<0.001).5.The influencing factors of Demodex folliculorum: According to the models of binary logistic regression,the history of myopic surgery were the risk factors for Demodex folliculorum(OR: 1.323,95% CI: 1.078～1.624,P=0.007);and after adjusting for confounding factors,the infection rate risk of Demodex folliculorum in the internal and median eyelash was higher than that in the external eyelash(OR: 1.794,95% CI:1.369～2.351,P<0.001;OR: 2.082,95%CI: 1.602～2.705,P<0.001).6.OSDI had no correlation with the number of Demodex folliculorum(P<0.05).The severity of itching,dryness and foreign body sensation had a positive correlation with the number of Demodex folliculorum(all P<0.05).Conclusion1.The detection rate of Demodex folliculorum in healthy young males was 13.18%,and more attention should be paid to the screening of ocular Demodex folliculorum infection in this population.2.There was no significant difference in the positive rate and detection degree of Demodex folliculorum between right and left upper eyelids.3.The positive rate of Demodex folliculorum in the internal and median eyelashes is higher than the external eyelashes,so the internal and median eyelash should be optimized to improve the detection rate of Demodex folliculorum examination.4.The history of refractive surgery is an important risk factor for Demodex folliculorum,and attention should be paid to prevention of ocular Demodex folliculorum infection in this population.5.Clinical symptoms of ocular Demodex folliculorum are often nonspecific,but the severity of eye itching,dryness,and foreign body sensation are related to the number of Demodex mites.It suggested that the ocular Demodex infection should be checked in the patients with the above symptoms.