Adults With Insufficiency-Type Esotropia May Need Larger-Than-Usual Surgical Doses

Traditionally, adults with esotropia who are treated with bilateral medial rectus recessions usually receive doses based on Marshall Parks’ tables; however, patients undergoing these surgeries for divergence insufficiency-type esotropia may need larger doses.

Study Design

A previously published observational study looked at 10-week and 12-month postsurgical outcomes in 110 adults with divergence insufficiency-type esotropia. This analysis focused on the subgroup of 42 patients who underwent bilateral medial rectus recessions, comparing surgical success rates in those receiving the “standard” surgical dose (per the Parks’ surgical tables) with those receiving a “greater than standard” dose (i.e., a total surgical dose of ≥0.6 mm over the standard dose). In this study, surgical success was defined as the patient reporting that they either “never” or “rarely” saw diplopia in the straight-ahead gaze.

Outcomes

Ten of the patients had doses corresponding to Parks’ dosage tables, while 32 had doses that were greater by a range of 0.6–2.0 mm. At 10 weeks, 67% of those receiving Parks’ dose were considered to have a successful surgical outcome compared with 91% of those receiving a greater than Parks’ dose. At 12 months, success rates were 56% and 78%, respectively, again favoring the greater than Parks’ group. Overall, the average surgical dose for the “successes” was 1.0 mm greater than Parks’ dose, compared with only 0.7 mm greater for the “failures,” at both 10 weeks and 12 months postoperatively.

Limitations

Partly due to the number of participants and the overall small differences in surgical doses, the authors were unable to definitively conclude that a greater than Parks’ dose in bilateral medial rectus recession surgery is superior to the standard Parks’ dose for adults with divergence insufficiency-type esotropia. Moreover, almost all of the patients (14/16) who had the surgery performed with adjustable sutures ended up having greater than Parks’ dosing; the authors noted that this made it difficult for them to independently assess the effects of adjustable sutures.

Clinical Significance

Results of this study suggest that when utilizing bilateral medial rectus recessions to treat divergence insufficiency-type esotropia in adults, clinicians could consider using a slightly greater dose than the standard Parks’ tables recommend.

Financial Disclosures: Dr. Robert Tauscher discloses no financial relationships.