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Yadan Quan, Tiran Zhang, Minbin Yu, Rong Lu; Quantitative Changes in Corneal Exposure during Vertical Gaze: A Clinical Model for Eyelid Contour Analysis. Invest. Ophthalmol. Vis. Sci. 2018;59(9):97.
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© ARVO (1962-2015); The Authors (2016-present)
We describe a quantifiable computerized method for the measurement of corneal exposure during vertical gaze.
Images of the palpebral fissure were acquired from 24 congenital ptosis patients and 64 volunteers with no history of eye disease in the primary position (0°), upgaze 40°, upgaze 20°, downgaze 20°, and downgaze 40°. Custom programs were used to define eyelid curvature and vertical palpebral fissure height (VPFH), and to calculate the corneal exposure percentage (CEP) at each gaze position.
In ptosis patients, the largest CEP was measured at downgaze 40°, and values decreased progressively with upgaze angle. In contrast, CEP was largest at the primary position in healthy controls and decreased in both vertical gaze directions. The mean VPFH change over the 80° range of vertical gaze was higher in congenital ptosis patients than controls (3.16 vs. 2.06 mm).
Analysis of CEP is an accurate and simple approach to describe eyelid contour. These data support the notion of levator muscle dysfunction in congenital ptosis patients during both upgaze and downgaze, and suggest that congenital ptotic upper eyelids remain relatively still during vertical gaze. However, this results in partial alleviation of visual deprivation from eyelid occlusion during downgaze in patients with congenital ptosis.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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