[Graded vertical rectus tenotomy for small angle vertical deviation]

Objective: To observe the effectiveness of the graded vertical rectus tenotomy procedure for small-angle vertical deviation. Methods: Retrospective case series study. Twelve patients, including 8 males and 4 females, with an average age of (48±8) years were treated in Tianjin Eye Hospital from January 2017 to December 2019 for diplopia in primary gaze by strabismus surgery. The disease duration was (15±7) months. MRI/CT scan of the orbits and brain was performed to exclude the orbital and craniocerebral diseases. All patients underwent ocular movement examination, with the prism and alternate cover test to detect the deviation angle in primary gaze and the double Maddox test. Based on the results, the posterior segment of the nasal/temporal superior/inferior rectus muscle was operated. The changes of vertical and cyclotorsion deviation angle and the relationship between the vertical rectus graded tenotomy and corrected vertical deviation angle were observed at 1 day after surgery and the last follow-up. The vertical deviation angle was represented by M (Q₁, Q₃). Friedman test (Bonferroni correction) and linear fitting analysis were used for statistical analysis. Results: The follow-up time of all patients was (7±3) months. The vertical deviation angle in primary gaze before surgery [7.00 (5.25, 7.75) PD] was significantly different from that at 1 day after surgery [1.00 (1.00, 2.00) PD] and the last follow-up [1.50 (1.00, 2.00) PD] (P<0.001, P=0.003). There was no significant difference in postoperative cyclotorsion in all patients. Linear fitting results showed that 50% to 90% vertical rectus tenotomy corrected 5 to 8 PD vertical deviation (R²=0.72; P<0.001). Conclusion: The graded vertical rectus tenotomy procedure can effectively improve the small-angle vertical deviation in primary gaze.