Graded Partial Tenotomy of Vertical Rectus Muscles for Treatment of Hypertropia

ABSTRACT

PURPOSE: To evaluate the effectiveness of graded (adjustable intraoperatively) partial vertical rectus muscle tenotomy at the insertion in correcting small degrees of hypertropia. METHODS: All patients with best corrected visual acuity of better than 6/30 in both eyes who had undergone only partial tenotomy of vertical rectus muscle(s) over a 30-month period were included. Improvement was evaluated 6 weeks postoperatively as the change in alignment in prism diopters (PD) in primary gaze and in the field of action of the affected rectus muscle(s). Binocular function was evaluated by Titmus stereoacuity and the Worth 4-light tests. RESULTS: All 24 patients who met the inclusion criteria had diplopia preoperatively, and this had resolved in 17 (71%) postoperatively (P<0.005). Prisms were used by 6 preoperatively vs. 2 postoperatively (P<0.05). The average vertical deviation in primary gaze decreased from 8 PD to 2 PD (P<0.005). In the field of action of the treated rectus muscle, hypertropia decreased from an average of 8 PD to 3 PD (P<0.005). For the available pre- and post-operative assessments, stereoacuity improved after 10 of the 18 (56%) procedures and Worth 4-light testing showed improvement or maintenance of fusion after 13 of 19 procedures (68%). CONCLUSIONS: Graded vertical rectus partial tenotomy can effectively reduce small degrees of hypertropia and associated diplopia, improve binocular function, and reduce or eliminate the need for prism correction.