Fig. 2
From: Quantitative analysis of the eyelid curvature in patients with blepharoptosis
The formulas for calculating the three evaluated indices. The upper lid contour index (ULCI) was computed by dividing the intercanthal distance by the upper lid margin length (a). To create area circularity index (ACI), a circle was drawn around the eye, with the line connecting the medial and lateral canthi serving as the diameter. The ACI was calculated by dividing the interpalpebral area by the size of the circle (b)