[Ultrasound of the upper eyelid to evaluate tarsal curvature in facial palsy].

BACKGROUND

Treatment of paralytic lagophthalmos involves surgical repair, requiring exact knowledge of eyelid anatomy. While there are extensive studies on anatomical eyelid measurements in healthy eyes, no data exist on the changes in the functional anatomy of the upper eyelid in paralytic lagophthalmos. The aim of this study, was to examine by ultrasound the upper lid tarsus during changes in the patient's line of vision, and to answer the question of whether there are changes in the curvature radius of the tarsus, caused by facial paralysis with resultant lagophthalmos.

MATERIAL AND METHODS

Two groups were formed. The first group consisted of 50 subjects with healthy eyes, and the second contained 47 patients with paralytic lagophthalmos. The upper lid tarsal radius, when looking straight ahead and in the abducted position, was determined by ultrasound with a 7.5 MHz scanner in the non-contact mode, and then compared statistically.

RESULTS

Both groups showed a highly significant difference in the tarsus curvature, when looking straight ahead and in the abduction position. While there was no significant difference between both groups in the abduction position, they differed significantly when looking straight ahead. Also, a significant difference was noted, between the eyes of healthy subjects and the healthy eye in patients with facial palsy.

CONCLUSION

The changes in curvature of the tarsal plate, when looking straight ahead, can be explained by the loss of tone in the paralyzed Orbicularis Occuli muscle. This means, that in addition to the lagophthalmos resulting from facial paralysis, changes occur in the functional anatomy of the upper eyelid, which must be considered during surgical correction. Additionally, the physiological loss of tone of the upper eyelid tarsal plate, which comes with age, has a certain influence.