Changes in refractive error and anterior segment parameters after isolated lateral rectus muscle recession

PURPOSE To evaluate the short-term effect of isolated lateral rectos muscle recession surgery on refractive error, corneal measurements, and anterior chamber depth and volume. METHODS Consecutive patients who underwent isolated lateral mails muscle recession from July 2008 to March 2009 were prospectively studied. Refractive error; corneal power, thickness, and volume; and anterior chamber depth and volume were measured (Pentacam) before and at 1 week and 1 month after surgery. Patients who could not maintain reliable fixation and those with sensory strabismus or a history of eye surgery were excluded. Pre- and post-operative measurements were compared by analysis of variance. RESULTS A total of 24 eyes of 24 patients (average age, 8 years) were included. Bilateral lateral rectus muscle recession was performed in 19 patients; unilateral in 5. Overall, patients manifested statistically significant changes in spherical equivalent, horizontal and mean keratometry, corneal astigmatism, anterior chamber volume, and center and peripheral anterior chamber depth at 1 week after surgery (P < 0.05). Changes became progressively smaller during the first month after surgery, although significant changes in spherical equivalent persisted at 1 month. CONCLUSIONS Lateral rectus muscle recession resulted in short-term changes in refractive error in this cohort. The etiology of the refractive change is unknown but could be due to alterations in muscle tension that affect corneal remodeling, segmental interruption of the ciliary body circulation affecting the lens curvature, postoperative tissue edema, and/or other postsurgical factors. The decrease in change after 1 month may be due to the effects of compensation by other quadrants of the eye or resolution of the surgical induced tissue damage. Longer follow-up is necessary to ascertain clinical significance.