Prism and Maddox rod test as a reliable tool for surgical targeting in small-angle AACE

This retrospective study aimed to evaluate the efficacy of the prism and Maddox rod test (PMT) in determining surgical targets for small-angle acute acquired concomitant esotropia (AACE). Thirty-three patients with small-angle AACE who underwent surgical treatment at the First Affiliated Hospital of Fujian Medical University from June 2017 to May 2023 were included. All patients underwent various tests, including the Hirschberg test (HT), PMT, and prism and alternative cover test (PACT). PACT measured the minimum value (PACTmin) and the maximum value (PACTmax) based on different interpretation criteria for examination endpoint. PMT results were used as the surgical target. Unilateral medial rectus recession (MRrec) was performed on all patients, and postoperative follow-up lasted up to 6 months to evaluate deviation angle and binocular vision. Both near and distance measurements from PMT were 23.67 ± 5.44 PD and 24.82 ± 5.49 PD, respectively, which were comparable to PACTmax (23.06 ± 2.65 PD and 23.58 ± 2.35 PD) and significantly higher than PACTmin (15.18 ± 5.12 PD and 15.24 ± 5.06 PD; P < 0.001). Post-surgery, the mean deviation angles for distance and near viewing were reduced to 0.73 ± 1.69 PD and 0.61 ± 1.35 PD (PMT and PACTmin, respectively). All patients achieved excellent surgical outcomes, with no noticeable deviation angles, diplopia disappearance, and restoration of normal binocular vision. Our study demonstrates that PMT serves as a reliable and practical method for determining surgical targets in patients with small-angle AACE. The results highlight its accuracy and consistency in measuring deviation angles, which can effectively guide unilateral MRrec.