Overaction of the inferior oblique(IO) muscle is manifested by elevation of the adducted eye and from the clinical point of view there are two types of overaction. The primary type is of unknown cause, whereas the secondary type is usually related to the palsy of the ipsilateral superior oblique or contralateral superior rectus. An ultrastructural study on the overacting IO muscles was performed compared to normal IO muscles by electron microscopy. Of 16 biopsies of overacting IO muscles, four had primary overacting inferior obliques and twelve had secondary overacting inferior obliques due to paralysis of superior oblique muscle. Additional four IO muscle, obtained from patients with intraocular diseases served as control specimens. The most striking abnormalities were aggregations of mitochondria and degenerating mitochondrial profiles and increased vacuolization in primary and secondary overacting muscles. Many muscle fibers were in different stages of atrophy, and hypertrophy and regeneration of muscle fibers were sometimes visible. The results suggest that the primary overacting IO muscle might be the result of a paresis of the superior oblique muscle.
Biopsy ; Humans ; Mitochondria/ultrastructure ; Ocular Motility Disorders/*pathology ; Oculomotor Muscles/*ultrastructure ; Ophthalmoplegia/pathology ; Vacuoles/ultrastructure

To verify the postoperative ultrastructural changes of the myotendinous nerve endings of feline extraocular muscles, which are known as proprioceptors. Sixteen recti of four cats were used and divided into three groups. In group A, eight lateral recti were recessed. In group B, four medial recti were resected by 10 mm from insertion to include the myotendinous junction. In group C, four medial recti were resected by 4 mm of muscle bellies only, without disturbing the myotendinous junction. Four weeks after surgery, specimens were examined with electron microscopy. In group A, overall neural structures were well maintained with slight axonal degeneration. In group B, only muscle fibers were observed without any regeneration of neural sprouts. In group C, axonal disintegration and shrinkage were evident. These results indicate that myotendinous nerve endings can be damaged in strabismus surgery, and that resection was more invasive than recession in disrupting myotendinous nerve endings.
Animals ; Cats ; Motor Neurons/ultrastructure ; Nerve Endings/*ultrastructure ; Neuromuscular Junction/*ultrastructure ; Oculomotor Muscles/*innervation/surgery ; Oculomotor Nerve/*ultrastructure ; *Ophthalmologic Surgical Procedures ; Receptors, Sensory/ultrastructure ; Strabismus/surgery ; Tendons/*innervation/ultrastructure

OBJECTIVE: To investigate histopathologic and ultrastructural changes of extraocular muscles (EOM) in thyroid associated ophthalmopathy (TAO). METHODS: Twelve EOM specimens from 11 patients with TAO were observed. Each of the specimen was stained with HE and observed by light microscope,and then was sectioned with ultrathin method and observed by transmission electronic microscope. RESULTS: Under the light microscope, sarcoplasm coagulation,granular degeneration, vacuolization and necrosis were found in the extraocular muscular cells.Under the electronic microscope, there were disturbance and disappearance of the Z line in part of muscular fibers and various degrees of sarcoplasmic reticulum dilatation, myofilament lysis and destruction with formation of vacuoles.In severe cases,the muscular cells could be completely destroyed and phagocytosed by macrophages,fibrosis occurred and myofibroblasts were found in some cases. CONCLUSION The extraocular muscles in TAO are destroyed at various degrees,and the muscular cells may be the target cells in TAO.
Adult ; Aged ; Female ; Graves Ophthalmopathy ; pathology ; Humans ; Male ; Middle Aged ; Oculomotor Muscles ; pathology ; ultrastructure

PURPOSE: To analyze innervated myotendinous cylinders (IMCs) in the extraocular muscles (EOMs) of normal subjects and strabismic patients. METHODS: The rectus muscles of 37 subjects were analyzed. Distal myotendinous specimens were obtained from 3 normal subjects, 20 patients with acquired strabismus, 11 with infantile strabismus, and from 3 with congenital nystagmus, and were studied by using light microscopy. Some specimens (6 rectus muscles) were also examined by transmission electron microscopy. RESULTS: IMCs were found in the distal myotendinous regions of EOMs. The IMCs of patients with acquired strabismus showed no significant morphological alterations. However, significant IMCs alterations were observed at the distal myotendinous junction of patients with congenital strabismus and congenital nystagmus. CONCLUSIONS: This study supports the notion that IMCs in human EOMs function mainly as proprioceptors, along with effector properties, and a disturbance of ocular proprioceptors plays an important role in the pathogenesis of oculomotor disorder. We suggest that a proprioceptive feedback system should be stimulated and calibrated early in life for the development of binocular vision.
Adolescent ; Adult ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Microscopy, Electron, Transmission ; Middle Aged ; Oculomotor Muscles/*innervation/physiopathology/ultrastructure ; Proprioception/physiology ; Strabismus/*pathology/physiopathology ; Young Adult