Background: The aims of this study are to investigate the expression of the main structural components of the tarsal extracellular matrix (ECM) in floppy eyelid syndrome (FES) focusing on elastic fibres and collagen types I and III, and also to identify possible cell-mediated inflammatory mechanisms in the pathogenesis of this condition.
Methods: A histopathological case control study was conducted using 30 upper lid specimens from patients with FES and 15 undiseased upper lid control specimens. Structural ECM components were assessed using a combination of immunctorial ataining ohistochemical and techniques including antibodies to collagens I and III, Verhöeff's iron haematoxylin, Gomori's aldehyde fuchsin and Lillie's oxidised aldehyde fuchsin. The contribution of different cellular components of the inflammatory response was investigated by immunohistochemical techniques using antibodies to CD3, CD20, CD68. Slide scoring was performed using a semiquantitative technique on an ordinal scale. Statistical analysis was performed using matched ordinal regression analysis.
Results: FES tarsal plate tissue demonstrated a decreased abundance of mature elastic fibres (P ≤ 0.001) and an increased abundance of oxytalan fibres (P = 0.006). Intensity of staining for collagens I (P = 0.012) and III (P < 0.001) was increased. No significant difference in the abundance of CD3, CD20 and CD68 expressing cells was identified.
Conclusions: The findings of altered elastic fibre phenotype and collagen accumulation are consistent with an adaptive response to cyclic mechanical loading of the tarsal plate, rather than an aetiological feature. These findings are important in understanding how the tarsal ECM responds to mechanical loading.