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The horizontal dynamic of the medial and lateral canthus
Todd Cook1, Robert Alan Goldberg, Raymond Douglas
1Division of Orbital and Opthalmic Plastic Surgery, Jules Stein Eye Institiute, UCLA School of Medicine, Los Angeles, California 90095, USA.
Purpose:
To identify and quantify the horizontal dynamic movement of the medial and lateral canthus in subjects without previous eyelid surgery.
Methods:
Prospective, experimental study.
Results:
Seventy-two eyes in 36 normal subjects were studied. Frontal view lateral canthal movement with abduction of the globe averaged -0.4 mm (negative numbers mean the canthus moves in the opposite direction of the globe), with a range of -3.8 to 2.1. Profile view lateral canthal movement with abduction of the globe averaged 1.6 mm, with a range of -2.2 to 4.7 mm. Frontal view lateral canthal movement with adduction of the globe averaged -0.3 mm, with a range of -3.7 to 3.9 mm. Profile view lateral canthal movement with adduction of the globe averaged 0.5 mm, with a range of -2.4 to 3.9 mm. Frontal view medial canthal movement with abduction of the globe averaged -0.4 mm, with a range of -3.9 to 1.5 mm. Frontal view medial canthal movement with adduction of the globe averaged 0.1 mm, with a range of -5.2 to 4.6 mm. Intrasubject variation was observed for all measurements.
Conclusions:
The medial canthus and the lateral canthus are dynamic structures that move with horizontal eye movements in patients who have not undergone canthoplasty. The measured movement of the lateral canthus differed, based on the position from which the measurements were made, and was not always in the direction of the globe. The movement of the lateral canthus and the medial canthus differed on the right and left sides of the same subject.