ABSTRACT
ABSTRACT: Purpose: To evaluate the thickness of horizontal rectus muscles in patients with esotropia by using magnetic resonance imaging (MRI), and to determine the effect of amblyopia on muscle tickness. Methods: Eighteen orthotropic volunteers and 50 patients with non-refractive and non-acommodative esotropia underwent orbital imaging prospectively. Esotropic patients were divided into 2 groups according to existance of amblyopia: Group I, 26 patients with amblyopia; group II, 24 patients with good visual acuity and alternating fixation. MRI was performed by using a fixation target and occluding each eye separetely. All MRI images were performed with axial T1 weighting by using 2 mm slice tickness. Mean tickness of horizontal rectus muscles of both groups were compared with that of the control group of the same age and sex. Results: The thickest MR (3.84 0.88 mm) and the thinnest lateral rectus (1.92 0.68 mm) values were with the amblyopic eye of group I. Lateral rectus thickness in the amblyopic eye of group I (1.92 0.68 mm) was thinner than both group II (2.37 0.59 mm) and controls (2.91 0.94 mm) (respectively p 0.029; p 0.000) The difference between the mean tickness of the medial rectus muscles of amblyopic eye of group I (3.84 0.88 mm) and controls (3.16 0.60 mm) was also significant (p 0.001). Conclusions: There are significant morphometric changes of horizontal rectus muscles in patients with non-refractive and non-acommodative esotropia and amblyopia. Further studies are necessary for different types of strabismus, and the correlation between our findings and surgical outcomes.
