LEVATOR PALPEBRAE SUPERIORIS FIBER SIZE IN NORMALS AND PATIENTS WITH CONGENITAL PTOSIS

A study of the histochemical staining of levator palpebrae superioris (LPS) was undertaken to measure the muscle fibre size in normal indivi duals and in patients with congenital dystrophic ptosis in order to se e whether there is an alteration in muscle fibre size in congenital pt osis. Eight LPS specimens were obtained: 4 from normal patients (3 fro m normal levator divided in a bilateral brow suspension procedure and 1 from an exenteration specimen) and 4 from levator resection procedur es for treatment of unilateral congenital ptosis. Cryostat sections fr om these specimens were stained histochemically to reveal muscle fibre types. The orthogonal diameters were measuring using a computer-gener ated program and the two groups compared using the Mann-Whitney U-test . No statistically significant difference in muscle fibre diameter was found between normals and patients with congenital ptosis. There was also no change in the distribution or range of muscle fibre diameter i n patients with congenital ptosis. Our findings do not support the cla ssification of congenital ptosis as a dystrophy.