Solanes F, et al. - In the present study, the researchers sought to examine clinical and imaging features of congenital and acquired causes of inferior rectus (IR) underaction. Cases of IR underaction were chosen from data prospectively obtained in a study of orbital imaging in strabismic patients. The review identified 3 cases of congenital IR underaction (2 with bilateral IR aplasia and 1 with unilateral IR hypoplasia), 12 acquired cases, including 4 due to denervation (2 idiopathic, 1 after multiple strabismus surgeries, 1 after head trauma), and 8 cases of direct IR damage (5 with orbital trauma and 3 with previous surgery, including 2 sinus surgery and 1 laser blepharoplasty). In patients with congenital or acquired IR hypofunction, orbital imaging shows a variety of abnormalities, helping to explain the underlying mechanism and guide management.