Evaluation of graded recession of inferior oblique muscle for correction of different grades of V-pattern strabismus

BACKGROUND: V pattern identification is essential for proper strabismus management. Graded recession is a tailored approach to treat inferior oblique overaction (IOOA). The aim is to evaluate the efficacy of graded recession of inferior oblique muscle for correction of different grades of V pattern. METHODS: Forty patients from 3 to 18 years old with V pattern strabismus and primary IOOA were evaluated by prism cover test to assess the grade of IOOA and amplitude of V-pattern. Graded recession of IO muscle depends on the amplitude of the V-pattern and degree of IOOA. Eight mm recession for amplitude 15 PD to 20 PD and mild IOOA (10 PD-15 PD or + 1) ,10 mm recession for amplitude 20–30 PD and moderate IOOA (15–25 PD or + 2) and maximum recession for amplitude more than 30 PD and marked IOOA (≥ 25 PD or + 3). Simultaneous correction of the horizontal deviation was performed. Follow up after I week,1 month ,3 month and 6-month. Trial Registration Number (TRN) (NCT05786053) on 23/3/2023. RESULTS: The mean age of the study patients was 9 ± 4.261. Twenty patients (50%) had V-pattern esotropia, 12 (30%) exotropia, 4 (10%) orthotropic and four (10%) had Dissociated vertical deviation (DVD). Four cases 10% were of grade 1, 20 cases (50%) grade 2 and 16 cases (40%) were of grade 3. Of eighty eyes, 66 eyes (82.5%) were fully corrected with no residual IOOA, and 14 eyes (17.5%) were under corrected. V-pattern was corrected in 28 cases 70% and only 12cases (30%) had residual V-pattern grade 1. CONCLUSIONS: Graded recession is an effective procedure for correction of V pattern strabismus with various grades of primary inferior oblique overaction. It can be tailored according to the the degree of IO overaction which is significantly related to the grade of V pattern. The 8 mm recession for IO was significantly related to recurrence or inadequate break of the V pattern in our studied cases. The grade of IOOA correlates with the amplitude of V-pattern. The amount of recession was planned according to preoperative IOOA and grade of V-pattern with frequent undercorrections obtained by the standard 8 mm recession. A + 2 overaction merits a 10-mm recession of the inferior oblique. A + 3 or + 4 overaction merits a 14-mm maximal recession.