A New Method of Surgical Dosage in Basic Concomitant Esotropia

Siddharth Agrawal

Purpose: To determine the accuracy of a new calculation method for correction of ocular deviation in relation to recession of medial rectus (MR) in patients of basic concomitant esotropia treated by unilateral recession and resection procedure.

Methods: A norm gram developed by the researchers taking into account the various calculation procedures available was studied in selected 36 patients of basic concomitant esotropia undergoing unilateral recession-resection procedure. Patients underwent 3.5 to 7 mm recession of MR in 1 eye depending on the preoperative deviation and patient's age. Together they also underwent 6, 7 or 8 mm resection of the lateral rectus in the same eye depending on the amount of MR recession (larger resection for a larger recession). In patients below 3 years a correction of 6,7 or 8 PD per mm of recession of MR was expected when the preoperative 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 per mm of MR recession in patients above 3 years. A ratio between achieved and expected correction was calculated and the calculation procedure 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.

Conclusions: The calculation procedure developed takes into account the various factors responsible for unpredictable results in concomitant esodeviation surgery. It can serve as a useful tool in patients of basic concomitant esotropia for minimizing variability of surgical results.