Evaluation Of lower Eyelid Retraction And Evaluation Of Lower Eyelid Laxity

    Lower eyelid retraction occurs in some patients with thyroid ophthalmopathy. The amount of retraction is measured by the distance from the inferior limbus to the lower eyelid temporally, centrally, and nasally. Normally, the lower eyelid is at the level of the inferior limbus. This measurement is helpful in determining the size of the grafts used to treat lower eyelid retraction.

    Another measurement is the margin reflex distance-2 (MRD2) (Fig. 3-9).5 The MRD2 is the distance from a corneal light reflex to the lower eyelid as the examiner and patient's eyes line up at the same level and the examiner shines a muscle light at the patient's eyes. This distance normally is about 5.5 mm but increases with lower eyelid retraction. The MRD2 also is helpful in determining the size of the grafts used to treat lower eyelid retraction.


    Laxity of the lower eyelid is evaluated when the surgeon pulls the lower eyelid downward and observes how quickly it snaps back to the eye (Fig. 3-10). Pinching full-thickness eyelid tissues together also helps in the evaluation of a redundant eyelid. In cases of marked horizontal lower eyelid laxity, redundant eyelid, or a slowness in the eyelid to snap back after eversion, the surgeon should consider a lower eyelid horizontal shortening/full-thickness temporal eyelid resection, lateral canthal tendon tightening or tarsal strip procedure in order to avoid a postoperative ectropion after resection of skin and fat.

    The examiner measures laxity of the lateral canthal tendon by pulling the lateral canthus nasally (Fig. 3-11). Normally, the lateral canthus moves only minimally with this maneuver; however, if the lateral canthus can easily be pulled to or beyond the lateral limbus of the eye, attenuation of the lateral canthal tendon must be suspected. Similarly, medial canthal tendon attenuation is diagnosed by the ease in pulling the medial canthus temporally. In either case, the surgeon should consider a lateral or medial canthal tendon tuck procedure, combined with a cosmetic blepharoplasty, in order to avoid a postoperative lower lid ectropion.

Figure 3-9 The margin reflex distance-2 (MRD2) is useful for measuring the amount of lower eyelid retracton. This is the distance from a corneal light reflex to the lower eyelid as the examiner and the patient's eye line up with each other and the examiner shines a muscle light at the patient's eyes.

 

Figure 3-10 A, The amount of horizontal laxity of the lower eyelid is determined by pulling the lower eyelid downward. B, Lack of elevation of the lower lid from the everted position on releasing the surgeon's finger indicates that the lower lid is horizontally lax and that an ectropion is likely to complicate lower eyelid cosmetic surgery.

Figure 3-11 Lateral canthal tendon laxity is measured by the ease with which the lateral canthus can be pulled nasally when the lower lid is drawn in this direction. This signifies the need for a lateral canthal tuck.