Age differences in ocular demodicosis: Demodex profiles and clinical manifestations

BACKGROUND: Demodex infestation is highly age-dependent. Intriguingly, our previous studies that focused on children and young adult patients suggested that the clinical features of young patients were different from those studies enrolling mainly elderly patients. Whether age plays a role between young and elderly patients with ocular demodicosis remains unclear. METHODS: This prospective comparative study included 91 patients younger than 35 years and 92 older than 45 years with ocular demodicosis. Demodex mite count, symptoms, tear film, and ocular changes were compared between the two groups. Risk factors of meibomian gland loss (MGL) and corneal changes were analysed in the two groups. RESULTS: Demodex counts were comparable between the two groups. Young patients had higher D. brevis counts and overall percentage of D. brevis, while elderly patients had more D. folliculorum (all P<0.05). Irritation and blurred vision were more common in young patients, while eye fatigue and photophobia were more common in elderly patients (both P<0.05). The two groups had comparable tear volume and tear break-up time. Meibomian gland dysfunction was the most common sign in both groups but MGL was significantly more severe in young patients. More prevalent corneal changes and more eyelash disorders were found in young patients (both P<0.05). Female sex, a higher D. brevis percentage, lid margin anomalies, and MGL were associated with corneal change, while a higher D. brevis percentage and lid margin anomalies were related to MGL in young patients. MGL was associated with corneal change, but age was the only predictor of MGL in the elderly group. CONCLUSIONS: Young patients with ocular demodicosis tend to have more D. brevis infestation, more MGL, and more corneal involvement.