BACKGROUND:
The relationship of the position of the globe, the lower eyelid, and the malar prominence is essential in selecting the optimum reconstructive procedure for the lower eyelid in facial paralysis.
METHODS:
45 patients with complete unilateral facial paralysis were evaluated retrospectively for the degree of recurrent paralytic lower eyelid ectropion at two years following the initial fascial sling procedure. All patients had placement of an upper eyelid gold weight loader. Photographic analysis of the eyelids defined the projection of the globe relative to the lower eyelid and malar projection. Negative, neutral, and positive vectors were identified and surgical outcomes were compared with each vector.
RESULTS:
55 % of patients showed a positive vector; 33% showed a neutral vector; 12% showed a negative vector. Recurring symptoms of lower eyelid paralytic ectropion following the achievement of excellent vertical support with fascial sling suspension included increased tearing, increased sensation of dryness, appearance of lagophthalmos, and an ectropion with scleral show. Examination at two years showed 16% recurrence in the positive vector group; 27% recurrence in the neutral group; 80% recurrence in the negative vector group.
Paralytic lagophthalmos results in unopposed action of the levator palpebrae superioris in the upper eyelid. The absence of orbicularis oculi function allows for a sagging lower eyelid secondary to gravity, decreased tone of tissue, and the degree of support provided by the malar bone. Insertion of a gold weight loader over the tarsal plate will initiate upper eyelid descent but is not strong enough to achieve complete closure alone. The lower eyelid must be supported in a vertical direction to achieve full closure and apposition.
Paralysis of the eyelids if untreated, results in epiphora, dryness, and subsequent corneal exposure and ulceration. Patients experience a marked improvement in symptoms once vertical support of the lower eyelid allows complete closure. Recurrence of lower eyelid ectropion can be avoided by attention to the malar and eyelid relationships. A high recurrence rate in patients with a negative vector indicates the need for an additional procedure such as tarsorrhaphy, to supplement the fascial sling, or the use of a composite cartilage graft as a primary procedure. Subsidence of the fascial sling below the apex of the convex contour of the globe in these patients is the cause of early recurrence of ectropion.
CONCLUSIONS:
Preoperative evaluation of lower eyelid/malar vectors will focus attention on mechanical forces that result in progressive loss of reconstructed vertical support in the paralyzed lower eyelid. Correct design of the primary procedure will reduce the recurrence of paralytic lagophthalmos.