Disinsertion of the levator aponeurosis from the tarsus in growing children.

To confirm when the levator aponeurosis is disinserted and how the disinsertion is compensated for in growing children, the earliest and latest photographs of the same children were the subjects of a retrospective comparative study regarding upward displacement of the superior palpebral crease and the eyeball in the palpebral fissure. Ninety-four children (48 boys and 46 girls) were selected from 615 patients with cleft lip and palate who were followed for more than several years at our outpatient clinic and whose 58,000 photographs were digitized. The earliest and latest photographs of the patients were taken in primary gaze position; the former, taken at less than 3 years of age, and the latter, taken at more than 6 years of age, were selected for this study. The intervals between the two photographs ranged from 3 to 14 years (mean, 9.61 years; SD, 3.11). The superior palpebral crease moved upward parallel with the growth of the children (p < 0.0001) as well as with the length of the growth period (p = 0.0141). The lower eyelid did not move downward (p < 0.0001). The eyeball also displaced upward parallel with growth (p < 0.0001) and with the length of the growth period (p = 0.0302). The more the superior palpebral crease was displaced upward, the more the eyeball was displaced upward (p = 0.0005). The levator aponeurosis may be likely to disinsert from the tarsus in growing children, thus requiring compensatory, excessive contraction of the levator muscle, which may cause upward displacement of the superior palpebral crease. Subsequently, excessive contraction of the superior rectus muscle in conjunction of the levator muscle may rotate the eyeball upward, which may incline the head. When the head is not inclined in the primary gaze position, compensatory contraction of the inferior rectus muscle to maintain the horizontal visual axis may displace the eyeball upward in the orbit by means of the inferior suspensory ligament of Lockwood.