Restrictive factors in strabismus

MRI measurements of orbital tissues in dysthyroid ophthalmopathy

“…Marked resistance on passive elevation was found with the force duction test [15]. Length-tension measurements of detached muscles during surgery demonstrated an increased stiffness of the inferior rectus and medial rectus muscles in patients who had marked restriction of elevation and abduction [21].…”

Eye muscle force development and saccadic velocity in thyroid-associated ophthalmopathy

“…The discrepancy between eye-movement velocity and force production in patients with TAO could be the result of an increased innervation to the agonist muscles in order to overcome the resistance to movement in dysthyroid muscles. Fibrosis and loss of elasticity of extraocular muscles have been supposed as importance aetiological factors in limitation of ocular motility [8]. Furthermore, since the steady-state tension was increased for movements in all directions of gaze, both vertically and horizontally, it would seem that the disease process affected all the external eye muscles, at least all the rectus muscles.…”

“…Velocity of saccadic eye movements has been reported to be normal in most cases [10], but decreased in cases involving compression of the optic nerve and possibly also of the nerves to the eye muscles [4]. The force duction test has shown mechanical restriction mainly on passive elevation and abduction [8]. Length-tension measurements of detached muscles during surgery showed increased muscle tension and reduced elasticity of affected eye [11].…”

Amniotic membrane in the management of strabismus reoperations

“…Intraoperative forced duction testing is very important, and it confirms the surgeons' preoperative diagnosis and demonstrates whether surgery has effectively relieved restrictions. Forced duction testing needs to be repeated several times during the surgical procedure to determine whether a restriction has been adequately relieved [17]. In our study, forced duction testing was positive preoperatively and negative at the end of the surgery in all cases except in patients 9 and 11, who had positive forced duction testing at the end of the surgery.…”