Ultrastructural Study on the Overacting Inferior Oblique Muscles.

Choi, Dong Gye; Chang, Bong Leen

Original Article

Journal of the Korean Ophthalmological Society 1993;34(4):337-344.
Published online April 1, 1993.

Ultrastructural Study on the Overacting Inferior Oblique Muscles.

¹Department of Ophthalmology, College of Medicine, Hallym University, Seoul, Korea.
²Department of Ophthalmology, College of Medicine, Seoul National University, Seoul, Korea.

하사근 기능항진시 하사근의 전자현미경적 소견

최동규(Dong Gyu Choi),장봉린(Bong Leen Chang)

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.

Key Words: Electron microscopy;Inferior obligue overaction;Primary;Secondary;Superior oblique palsy