The correlation between Demodex infestation and meibomian gland dysfunction at different ages

BACKGROUND: This study aimed to explore the associations between Demodex infestation and the ocular surface characteristics of meibomian gland dysfunction (MGD) in different age groups, to further understand the effect of Demodex on MGD. METHODS: A total of 202 consecutive MGD patients aged 18 to 70 years were randomly recruited. All patients were divided into two groups based on their age: young patients (18–40 years) and elderly patients (41–70 years). The main observations were the different relationship between Demodex infestation and ocular surface and meibomian gland (MG) parameters in two age groups. We also compared ocular surface and MG parameters between the young and the elderly groups. Demodex infestation was diagnosed based on expert consensus in China. RESULTS: Our results indicated significant differences among young Demodex-positive, suspicious-positive, and negative patients in MG dropout (P = 0.000), plugging of MG orifices (P = 0.000), lid margin abnormality (P = 0.000), and meibum quality (P = 0.000). In elderly patients, there were significant differences among the Demodex-positive, suspicious-positive, and negative groups in terms of ocular surface disease index (OSDI) (P = 0.037), fluorescein tear film break-up time (FBUT) (P = 0.002), corneal fluorescein staining (CFS) (P = 0.036), MG dropout (P = 0.000), plugging of MG orifices (P = 0.008), lid margin abnormality (P = 0.000), and MG expression (P = 0.037). The mean number of mites in elderly Demodex-positive patients (10.64 ± 7.50) was greater than that of in young patients (7.60 ± 4.71) (P = 0.014). MG dropout (P = 0.000), plugging of MG orifices (P = 0.006), lid margin abnormality (P = 0.000), MG expression(P = 0.001), and meibum quality (P = 0.032) were more severe in elderly Demodex-positive patients. Additionally, FBUT (P = 0.005) was lower and tear film lipid layer thickness (LLT) (P = 0.001) was higher in the elderly. CONCLUSION: The effect of Demodex infestation on the ocular surface and MG parameters of MGD was different in patients of different ages. It is necessary to pay more attention to the diagnosis and treatment of Demodex infestation in MGD.