J Korean Ophthalmol Soc.  1993 Apr;34(4):337-344.

Ultrastructural Study on the Overacting Inferior Oblique Muscles

• Choi DG
• Chang BL

Abstract

The primary overaction of the inferior oblique(IO) muscle is of unknown cause, whereas the secondary overaction of IO is usually related to the palsy of the ipsilateral superior oblique or contralateral superior rectus. To understand the cause of the primary overaction of the IO, an ultrastructural study on primary and secondary overacting IO muscles was performed by electron microscopy. The most striking abnormalities were aggregations of mitochondria, degeneration of mitochondrial profiles, and increased vacuolization in primary and secondary overacting muscles. These changes were more severe in cases of primary overaction thitn in those of secondary overaction. Many muscle fibers were in different stages of atrophy. Hypertrophy and regeneration of muscle fibers were sometimes visible. The primary and the secondary overacting IO muscles showed similar morphologic alterations. These results suggest that the primary overacting IO muscle might be the result of a paresis of the superior oblique muscle.

Keyword

Electron microscopy; Inferior obligue overaction; Primary; Secondary; Superior oblique palsy

MeSH Terms

Atrophy
Hypertrophy
Microscopy, Electron
Mitochondria
Muscles*
Paralysis
Paresis
Regeneration
Strikes, Employee