Abstract
Purpose: :
To evaluate age-related Meibomian Glands (MGs) changes by in vivo laser scanning confocal microscopy (LSCM).
Methods: :
One hundred eyes of 100 healthy subjects were enrolled in this study. The subjects were divided into six groups according to age: A (20-30 years; 12 men and 8 women; average age 22,5 ± 3,5), B (30-40 years; 9 men and 6 women; average age 34,5 ± 0.7), C (40-50 years; 6 men and 6 women; average age 45 ± 7,1), D (50-60 years; 8 men and 9 women; average age 53 ± 4,2), E (60-70 years; 7 men and 11 women; average age 63,5 ± 0,7), F (over 70 years; 9 men and 9 women; average age 73 ± 4,2). Inclusion criteria for these volunteers included Ocular Surface Disease Index score < 13. We also enrolled 2 other groups of subjects: G (under 40 years; 6 men and 6 women; average age 31,9 ± 5,4) and H (over 65 years; 8 men and 4 women; average age 75,6 ± 8,5). These groups were enrolled without considering the OSDI score. Exclusion criteria for all groups included blepharitis, ocular allergies, contact lens wear, continuous eye drop use, history of ocular trauma or surgery, systemic or ocular diseases that would interfere with tear film production or function. All the subjects underwent a full ocular surface evaluation. LSCM was used to study MGs in the lower eyelid, quantifying the mean acinar units diameter (manually measured as the longest axis of the acinar unit), density of MGs (manually marked and calculated automatically with the Cell Count software, Heidelberg Engineering GmbH, Dortmund, Germany), diameter of glandular orifices (manually marked as the longest axis of orifice); meibum secretion reflectivity; inhomogeneous appearance of interstice and wall of acinar units.
Results: :
MGs acinar units density decreased with age, with significant differences among the groups A-F (P<0.001; Kruskal Wallis H test). The mean acinar diameter showed significant decrease in E and F groups compared with A-D groups (P<0.01; Mann-Whitney U test). Meibum secrection reflectivity and inhomogeneous appearance of acinar wall increased with age, with significant differences among the groups A-F (P<0.001; Kruskal Wallis H test). Comparing H to G group, we found decreased acinar units density and increased secrection reflectivity and wall inhomogeneous appearance (P<0.01; Mann-Whitney U test). Between these 2 groups, the mean acinar diameter showed no significant difference but very different standard deviations (47.2±9.8 and 45.6±20.15 for G and H groups respectively).
Conclusions: :
LSCM allows to study age-related MGs changes, showing the in vivo histological features underlying the clinically observed MGs dropout. Comparing elderly volunteers with and without mild ocular surface symptoms, we can obtain interesting information about the boundary between physiological and pathological aging.
Keywords: cornea: tears/tear film/dry eye • aging • imaging/image analysis: clinical