[Pathological features of levator aponeurosis in patients with involutional blepharoptosis]

Objective: To observe pathological features of levator aponeurosis in patients with involutional ptosis. Methods: A prospective study. Twenty-nine consecutive patients with involutional blepharoptosis who underwent levator aponeurosis advancement surgery for blepharoptosis correction were enrolled at Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University from 2007 to 2013. Twenty-nine specimens of the levator aponeurosis were obtained during surgery. Hematoxylin-eosin staining, Van Gieson staining, Masson staining, immunohistochemistry and transmission electron microscope observations were performed to observe the features of levator aponeurosis. Twelve normal specimens of fresh levator aponeurosis were obtained from Beijign Tongren Eyebank as control group. Mann-Whitney's U-test and multiple linear regression were used for statistical analysis. Results: Among the enrolled cases, there were 19 males and 10 females;14 cases were diagnosed with moderate ptosis and 15 cases with severe ptosis;9 cases involved with both eyes, 9 cases with right eyes, and 11 cases with left eyes. The mean age was 59 years. Among the 12 normal cases, there were 5 males and 7 females. The mean age was 56 years. Histopathological observation showed fascicle disruption(+++, ++, + 24, 2, 3 vs. 0, Z=-5.666, P<0.001), scarcity of cross-striations(+++, ++, + 23, 2, 4 vs. 0, Z=-5.582,P<0.001), collagen fibers hyperplasia(+++, ++, + 15, 10, 4 vs. 0, Z=-5.223,P<0.001), fatty infiltration(+++, ++, + 24, 5, 0 vs. 0, Z=-5.671,P<0.001), and a decrease of myoglobin expression(+++,++,+,- 9, 1, 1, 15 vs. 8, 1, 0, 0, Z=-3.004, P=0.005) in levator aponeurosis. Transmission electron microscope recorded presence of collagen fiber hyperplasia and cellular degeneration including mitochondria swelling and hyperplasia, vacuoles, lipid droplets, nucleus pycnosis, chromosome condensation, disintegrated organelles, myeloid body and autophagy. Multivariate linear regression showed a correlation between fat infiltration and age(β=0.425, P=0.043) while suspicious related clinical features as independent variables and observed histopathological features as dependent variables. Conclusion: The levator aponeurosis appears to be involved with muscle fiber degeneration, collagen fiber hyperplasia and cellular degeneration in patients with involutional blepharoptosis. (Chin J Ophthalmol, 2018, 54: 671-677).