Objective: This study determined the incidence and density of Demodex species on the eyelashes of subjects with normal eyelids, anterior blepharitis (AB), meibomian-gland dysfunction (MGD), and mixed blepharitis (MB). Methods: Consecutive patients diagnosed with AB, MGD, and MB were recruited, along with 50 normal individuals who served as controls. All underwent a standard eye exam. Data on demographics and ocular symptomatology were gathered. Digital photographs of the lid margins were taken. Lash sampling was done using the modified Coston procedure for epilating lashes. The collected lashes were checked for Demodex based on morphology and motility, and the total number of Demodex identified were tabulated for each eye. Patients with AB and MB had eyelid bacterial culture. Data were subjected to statistical analyses. Results: A total of 167 patients with mean age of 53.7 years were included: 40% with MGD, 12% with AB, 19% with MB, and 30% normal. The overall incidence of Demodex infestation was 73%; 85% for MGD, 95% for AB, 97% for MB, and 34% for control group. The mean density count (MDC) was 13.63 for MB, 8.95 for AB, 4.08 for MGD, and 0.98 for the normal group. The incidence and density of Demodex infestation increased with age. Symptoms of irritation correlated with high MDC (>9 mites) (p <0.04). Asymptomatic patients had low MDC (0 to 2 mites) (p < 0.01). Sixty-eight percent of patients with cylindrical dandruff (p <0.001) and 36.1% with plugged meibomian glands (p < 0.001) had high MDC, while 82.7% with no eyelash findings had low MDC (p < 0.001). Conclusion The incidence and density of Demodex infestation was highest among patients with AB and MGD. Lid irritation and presence of cylindrical dandruff were indicative of high density count. These should alert the clinician to treat concomitant Demodex infestation of the eyelashes.
Meibomian Gland Dysfunction