EFFECTS OF STRABISMUS SURGERY ON CORNEAL TOPOGRAPHY

Background: Changes in refraction follow surgery on the extraocular mu scles. We examined corneal topography before and after medial or later al rectus muscle recession using a computer-assisted topographic analy sis system. Methods: A total of 36 patients (52 eyes) were examined. M easurements were taken 1 day before surgery and 1, 15, and 30 days aft er surgery. Results: A significant change in astigmatic power was dete cted 1 day after surgery in the meridian of the recessed muscle, evide ncing a localized flattening of the cornea. Induced astigmatism decrea sed over time. At 30 days following surgery, 6% of patients evidenced a residual change higher than 1 diopter (D); 12% evidenced a residual change higher than 0.5 D. Conclusion: The increase of astigmatic power recorded 1 day after surgery is higher for medial rectus muscle reces sion than for lateral rectus muscle recession. Corneal topography chan ges, located mainly in the meridian of the recessed muscle and the opt ical zone, are greatly reduced or gone within 1 month of surgery.