Comparison of biomicroscopy and light microscopy findings in demodex diagnosis in patients with chronic blepharitis

OBJECTIVES: We aimed to compare the results of biomicroscopic examination and light microscopy in the diagnosis of Demodex infestation in chronic blepharitis cases. METHODS: The study was performed with retrospective data and included patients with chronic blepharitis and who were admitted to the Medipol University Ophthalmology Outpatient Clinic. Biomicroscopic evaluation was performed intentionally under 40x magnification to investigate the presence of Demodex ectoparasites. Three or four pieces of eyelashes were obtained from all cases with epilation technique, and Demodex parasites were examined under ×100 and ×400 magnifications with light microscopy. The presence of one or more Demodex parasites in the examined area under light microscopy was considered to be positive for infestation. We calculated sensitivity, specificity, false-positive rate, false-negative rate, and positive and negative predictive values of biomicroscopic examination compared with those of positive light microscopy. RESULTS: Of the 255 subjects included in the study, 134 (52.5%) were men and 121 (47.5%) were women. The mean age was 43.9±11.9 years. Of the 255 chronic blepharitis cases, 130 (51%) presented Demodex infestation on light microscopy. We calculated the sensitivity, specificity, false-positive rate, false-negative rate, positive predictive value, and negative predictive value and were found to be 83.07%, 90.4%, 9.6%, 16.9%, 90%, and 83.7%, respectively, for the biomicroscopic examination. CONCLUSIONS: Careful biomicroscopic examination can be time-efficient and cost-effective, and the need for more advanced and invasive procedures for the identification of Demodex in patients with chronic blepharitis can be reduced.