Erin M. Shriver, Benjamin P. Erickson, Andrea L. Kossler, David T. Tse

To highlight features of lateral canthal tendon disinsertion (LCTD), provide an algorithm for systematic assessment, and describe the anatomic genesis of signs and symptoms. Retrospective case series of consecutive patients with lateral canthal tendon disinsertion, who underwent lateral canthal tendon fixation by a single surgeon (DTT) between 2004 and 2011. One hundred and seventeen eyes in 90 patients underwent lateral canthal tendon fixation. Average age was 69.3 ± 17.9 years. Twenty-three percentage of eyes had undergone lower eyelid blepharoplasty and 52% had undergone lateral canthal tightening; 35% had no previous periocular surgery. Patients with purely involutional lateral canthal tendon disinsertion were significantly older (76.1 ± 7.8 years of age; p < 0.03). Six key features associated with lateral canthal tendon disinsertion were identified. On static evaluation: 1) a blunted or vertically displaced lateral canthal angle; 2) a narrow horizontal fissure with reduced temporal scleral triangle; and 3) pseudo eyelid retraction. On dynamic evaluation with attempted closure: 4) medial and inferior movement of the lateral commissure; 5) incomplete apposition of the eyelid margins in the absence of anterior lamellar shortage; and 6) temporal eyelid imbrication. Improved blink dynamics with manual lateral canthal tendon complex repositioning ("the thumb test") predicted a favorable outcome with surgical tightening in 95.7% of cases. Lateral canthal tendon disinsertion results in altered eyelid fissure symmetry, blink dynamics, and lacrimal pump function. The authors recommend the mnemonic-A.B.C.: for Aperture configuration, Blink dynamics, and eyelid Closure-to structure the examination of all symptomatic patients. Manual restoration of the disinserted lateral canthal tendon with the "thumb test" predicts favorable outcomes with surgical fixation.