Structural features of extraocular muscles of children with strabismus
A. J. Martinez, A. W. Biglan and D. A. Hiles
Ninety extraocular muscle (EOM) biopsy specimens from 80 children with
strabismus and normal ocular alignment were studied by light microscopy,
enzyme histochemistry, and electron microscopy. Light microscopy showed
considerable variation in muscle fiber shape and size with sarcomere
disruption, sharp increases in endomysial and perimysial collagen, numerous
vacuoles and subsarcolemmal inclusions. Electron microscopy showed
disruption of myofilaments, nemaline rods, abnormal mitochondria,
leptomeric profiles, occasional "myelin figures," glycogen, and lipid-like
droplets. Some intramuscular nerves contained long-spacing collagen ("Luse
bodies"). Unlike somatic skeletal muscle, EOM showed a consistent lack of
mosaic pattern and reciprocal stain activity between fiber types noted by
enzyme histochemistry. Quantitative observations indicate that minimal but
consistent morphologic differences exist between strabismic and
nonstrabismic EOM. The role these changes play in the pathogenesis of
strabismus and their significance remains unclear.
