The Change in Ocular Alignment between the First Day and Six Weeks following Eye Muscle Surgery

Abstract

Sixty-four consecutive patients having standard horizontal eye muscle surgery were studied prospectively. Distance (6 m) measurements (double masked) in primary position on the first postoperative day and six weeks later were compared. The magnitude and direction of changes in measurement were analyzed.

There was an average change in alignment during this period of 9 prism diopters, with a range of 0 to 41 prism diopters. The direction of change was usually a return toward the preoperative alignment but there were many exceptions and great variability.

The change was virtually unpredictable with the exception of three groups of patients with good fusion potential: intermittent exotropes drifted an average of 15 prism diopters exo; decompensated accommodative esotropes drifted an average of 10 prism diopters eso; other acquired esotropes averaged no drift. Even within these three groups, there was significant individual variation.

Other patients and especially those with poor fusion potential were found to have such erratic and unpredictable changes in both direction and magnitude of ocular alignment from day one to six weeks later, that no such predictions could be made for them. For infantile esotropes undergoing this surgery, age at time of surgery was more predictive of alignment at 6 weeks, than alignment on day one. Changes of alignment following reoperations for both residual and consecutive deviations, were as a group, the least predictable of all.

• strabismus
• surgery
• fusion
• esotropia
• exotropia
• postoperative drift
• adjustable sutures