AIM:To measure the thickness of the normal levator palpebrae muscle by using ultrasound biomicroscopy(UBM)and to provide clinical guidance for the surgical treatment of blephamptosis.

METHODS:Seventy-five cases(150 eyes)with normal levator palpebrae muscle were collected in our hospital. The normal levator palpebrae muscle was categorized into youth group(aged 20～39), middle-aged group(aged 40～59)and older group(aged >60), 25 cases with 50 eyes in every group. The number of male was 30(60 eyes)and the number of female was 45(90 eyes).UBM was applied to measure the thickness of levator palpebrae muscle of each eye. The results were analyzed statistically and to see if the thickness might be effected by age or gender.

RESULTS:The mean thickness of levator palpebrae muscle in youth group, middle-aged group and older group were 0.833±0.054, 0.723±0.021 and 0.644±0.037mm respectively. The mean thickness was 0.748±0.100mm in females and 0.734±0.078mm in males. By one-way ANOVA, the thicknesses of levator palpebrae muscle among the three different groups were different, and the differences were statistically significant(P<0.01). There was no significant difference on the thickness of the levator muscle between gender.

CONCLUSION:UBM is a covenient,non-invasive test which can be used to measure the thickness of the levator palpebrae muscle. The levator palpebrae muscle becomes thinner gradually as aging, even without senile blepharoptosis, and the gender has nothing to do with the thicknesses of levator palpebrae muscle.