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Jeong-Min Hwang, Ji Eun Lee, Hee Kyung Yang; Relationship between Ocular Versions and Superior Oblique Muscle Hypoplasia in Unilateral Superior Oblique Palsy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):608. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate changes of binocular motilities in subjects with unilateral superior oblique palsy (SOP) according to the trochlear nerve absence or congenital/acquired etiologies using magnetic resonance imaging (MRI).
Eighty-seven subjects who had a normal trochlear nerve (present group) and 79 subjects without a trochlear nerve (absent group) who were diagnosed with unilateral SOP and had undergone high-resolution thin-section MRI images were retrospectively reviewed. Cross sectional areas of bilateral SO muscles was analyzed on MRI images at the point of optic nerve-globe junction. The areas of SO muscles and ocular motility parameters were compared in subjects according to the trochlear nerve absence or etiologies.
There was no intergroup difference of ocular motilities according to the trochlear nerve absence or not. The subjects with congenital etiology (congenital group) showed greater degree of ipsilateral underdepression in adduction (-1.4 ± 1.1 vs. -1.0 ± 1.0, P = 0.035) than acquired group. In congenital group, the degree of ipsilateral overelevation in adduction was positively correlated with the ratio of SO area (P/N) (r = 0.219, P = 0.017) which was independent on the trochlear nerve absence. The acquired group that all subjects have a normal trochlear nerve showed absence of correlation between SO size and ocular motilities. The ratio of SO area (P/N) was negatively associated with trochlear nerve absence (P < 0.001) and the hypertropia differences between both tilt (P < 0.001), but positively associated with hypertropia differences between both gazes (P < 0.001).
The ratio of SO area (P/N) which reflects binocular relation might attribute to the alterations of ipsilateral ductions in unilateral congenital SOP rather than the isolated factor such as the paretic SO muscle size. This finding suggests that binocular complex adjustments mediate changes of ocular version in unilateral congenital SOP.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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