[The effect of weakening inferior oblique muscles on the status of ocular torsion].
OBJECTIVE
To understand the clinical significance of subjective and objective examination of cyclodeviations and investigate the effect of weakening inferior oblique muscles on the status of ocular torsion.


METHODS
Twenty patients (40 eyes) with overacting inferior oblique muscles underwent bilateral myotomy or partial myectomy of inferior oblique muscles. Subjective cyclodeviations were measured before surgery as well as one week, two months after surgery by double maddox rod test (DMRT). Objective cyclodeviations were assessed by fundus photography before and 7 days after surgery in 15 cases. The photograph was transferred to a computer, and the fovea-disc angle was measured by means of drawing picture software.


RESULTS
Nine patients with primary overaction of inferior oblique muscles were negative with DMRT before surgery, and only one case revealed incyclotropia 5.0 degrees tested two months after surgery. Four out of 11 patients with secondary overaction of inferior oblique muscles showed excyclotropia 2.5 degrees - 5.0 degrees with DMRT before surgery, and all patients indicated no subjective cyclotropia with DMRT two months after surgery. Fundus photography determination of the right eye revealed extorsion 16.83 degrees +/- 6.39 degrees, the left eye 14.92 degrees +/- 4.51 degrees before surgery. The reduction of the cyclodeviations by weakening inferior oblique muscle for the right and left eye was 13.07 degrees +/- 3.38 degrees and 10.54 degrees +/- 3.75 degrees respectively. The comparison of objective ocular torsion for both eyes showed high significant differences (P < 0.01) pre- and post-operatively.


CONCLUSIONS
The results of subjective and objective examination of cyclodeviations in patients with primary or secondary overacting inferior oblique muscle early after birth were not consistent. Weakening inferior oblique muscle could correct excyclodeviation. There exist complicated compensatory mechanisms for subjective change of ocular torsion after surgery. The changes of subjective and objective cyclodeviations are still inconsistent.
Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, China. ghm44@163.com
Guang-Huan
GH
Mai
Xin-Ping
XP
Yu
Huan-Yun
HY
Yu
Jing-Chang
JC
Chen
Da-Ming
DM
Deng
Xiao-Ming
XM
Lin
Ying
Y
Kang
He-Ping
HP
Wu
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D018908:Muscle Weakness / Q000503:physiopathology*; D015835:Ocular Motility Disorders / Q000503:physiopathology / Q000601:surgery*; D009801:Oculomotor Muscles / Q000503:physiopathology*; D013285:Strabismus / Q000601:surgery; D014102:Torsion Abnormality / Q000601:surgery; D016896:Treatment Outcome