Evaluating a new surgical dosage calculation method for esotropia.

PURPOSE

To evaluate a simplified method for correction of ocular deviation in patients of infantile and acquired basic esotropia.

MATERIALS AND METHODS

Thirty-six consecutive patients of infantile and acquired basic esotropia were selected for this study. Patients underwent unilateral recession-resection surgery as per the new norm gram. Patients underwent 3.5-7 mm recession of medial rectus (MR) in one eye depending on the pre-operative deviation and patient's age. Together they also underwent 6 or 7 mm resection of the lateral rectus (LR) in the same eye depending on patient's age (6 mm for 3 years and below and 7 mm for older age). In patients 3 years and below, a correction of 6, 7, or 8 PD/mm of recession of MR was expected when the pre-operative deviation was lesser than 30 PD, between 30 and 60 PD, or above 60 PD, respectively. Similarly, these values were 5, 6, and 7 PD/mm of MR recession in patients above 3 years. A ratio between achieved and expected correction was calculated and the calculation was deemed successful for a patient if this ratio fell between 0.9 and 1.1.

METHODS

Thirty-six consecutive patients of infantile and acquired basic esotropia were selected for this study. Patients underwent unilateral recession-resection surgery as per the new norm gram. Patients underwent 3.5-7 mm recession of medial rectus (MR) in one eye depending on the pre-operative deviation and patient's age. Together they also underwent 6 or 7 mm resection of the lateral rectus (LR) in the same eye depending on patient's age (6 mm for 3 years and below and 7 mm for older age). In patients 3 years and below, a correction of 6, 7, or 8 PD/mm of recession of MR was expected when the pre-operative deviation was lesser than 30 PD, between 30 and 60 PD, or above 60 PD, respectively. Similarly, these values were 5, 6, and 7 PD/mm of MR recession in patients above 3 years. A ratio between achieved and expected correction was calculated and the calculation was deemed successful for a patient if this ratio fell between 0.9 and 1.1.

RESULTS

The calculation procedure was successful in 33 out of 36 patients (91%). The two-tailed probability on paired Wilcoxon test was 0.187.

CONCLUSIONS

This simplified method of surgical dosage calculation using MR recession as basis is predictable in patients of infantile and basic Esotropia. It may serve as a useful tool for minimizing variability of surgical results.