Lower Eyelid Contour in Graves Orbitopathy
Purpose: The aim of the present study was to analyze quantitively the lower lid contour of patients with Graves orbitopathy.
Methods: Bézier curves were manually adjusted to the ciliated and nasal (or lacrimal) portions of the lower lid contour of 41 patients with Graves orbitopathy and 43 normal subjects using National Institute of Health (NIH) ImageJ software. Considering the main coordinates of the Bézier functions, the Matlab software was employed to express the lid contours with 1000 points. The first order numerical derivative of the curves was calculated in order to compare the curvature of the whole lid contour of patients and controls. The same comparison was made for the temporal and nasal contour segments. Other parameters measured included the location of the lowest point on the contours (contour peak); the position of the lateral and medial canthi, as well as the angle formed by the lower lacrimal punctum and the vertex of the inner canthus.
Results: The curvature of the temporal portion of the lid contours of patients and controls correlated with both the height of the lateral canthus and the magnitude of the MRD2. Graves retraction affects the medial and lateral portion of the lid. Both segments were more curved in patients than in controls. The lower punctum was significantly lowered, increasing the angle between the lower punctum and the medial canthus.
Conclusions: The increased lateral curvature of the lower lid seen in patients with Graves disease is a natural geometric effect of the increment of MRD2. The nasal portion of the lid is also significantly lowered by retraction.