Lower medial resection in Convergence Insufficiency

Purpose: Convergence insufficiency can be treated with converging exercises or base-in prism glasses. Surgery for convergence insufficiency generally includes a medial resection. However, this may cause a secondary esotropia at distance. In this study we present the results of resection of only 2-4 mm of the lower part of the medial rectus. Results are combined from two centers: Houston, Texas, USA and Univrsity of L'Aquila, Italy. Methods: 33 patients who had 10-18XT' at near, 4-10x at distance, had lower part medial resection of 2-4mm. 6/33 had surgery on both medials. 8/33 had lower 2-3mm tenotomies on one or both laterals for XT 6-10 at distance. General guidelines are 2mm for 8-10x', 3mm for 10-12x', and 4mm for 13-16X'. Or perform 2 1/2mm-3mm resection OU for 16-18x'. If scarring was observed on inferior rectus it was removed. If the medial becomes tighter the resection is decreased by 1/2 to 1mm. Results: Xt' at near decreased to 0-6X'. XT at distance usually decreased by 2-4 prism diopters. A few cases had early esophoria at distance and/or near up to 6 prism diopters that resolved with time. Operate on eye with wider palpebral, since resection narrows fissure by 1/2 mm. Conclusion: Lower medial resection allows an effective decrease in the excess exotropia at near, without creating esotropia at distance.