BACKGROUND: In order to determine the short- and long-term influence of strabismus surgery on corneal curvature, a prospective study was carried out measuring corneal topography before and after operation. PATIENTS AND METHODS: Corneal topography was performed using a computer assisted videokeratoscope. 77 eyes of 74 patients were examined 1 day before and 1 day as well as 3 months after surgery. Data of the semimeridians at 0 degree, 90 degrees, 180 degrees and 270 degrees in the 3-, 5- and 7-mm zone and of the corneal center were analyzed. Objective refraction, induced astigmatism and simulated keratometer reading were evaluated. 39 horizontal recess-resect procedures. 12 inferior rectus recessions, 10 horizontal resections. 10 inferior oblique recessions and 6 other procedures were performed. RESULTS: The spheric equivalent of objective refraction decreased by 0.23 D. The absolute astigmatism increased by 0.16 D, the maximum change was 1 D. Changes of objective refraction were statistically not significant. The simulated keratometer reading increased by 0.2 D postoperatively and returned to the initial value after 3 months. With few exceptions, corneal topographic changes were small, statistically not significant and nearly disappeared after 3 months. Corneal flattening tended to occur in the semimeridian of resection while corneal steepening was observed at the site of recession. CONCLUSIONS: The influence of strabismus surgery on corneal astigmatism is usually small and mostly transitory. In a few cases, however, the induced astigmatism persists. Patients should be informed about this possibility preoperatively.
BACKGROUND: In order to determine the short- and long-term influence of strabismus surgery on corneal curvature, a prospective study was carried out measuring corneal topography before and after operation. PATIENTS AND METHODS: Corneal topography was performed using a computer assisted videokeratoscope. 77 eyes of 74 patients were examined 1 day before and 1 day as well as 3 months after surgery. Data of the semimeridians at 0 degree, 90 degrees, 180 degrees and 270 degrees in the 3-, 5- and 7-mm zone and of the corneal center were analyzed. Objective refraction, induced astigmatism and simulated keratometer reading were evaluated. 39 horizontal recess-resect procedures. 12 inferior rectus recessions, 10 horizontal resections. 10 inferior oblique recessions and 6 other procedures were performed. RESULTS: The spheric equivalent of objective refraction decreased by 0.23 D. The absolute astigmatism increased by 0.16 D, the maximum change was 1 D. Changes of objective refraction were statistically not significant. The simulated keratometer reading increased by 0.2 D postoperatively and returned to the initial value after 3 months. With few exceptions, corneal topographic changes were small, statistically not significant and nearly disappeared after 3 months. Corneal flattening tended to occur in the semimeridian of resection while corneal steepening was observed at the site of recession. CONCLUSIONS: The influence of strabismus surgery on corneal astigmatism is usually small and mostly transitory. In a few cases, however, the induced astigmatism persists. Patients should be informed about this possibility preoperatively.
Authors: J Mehlan; H Thormählen; M K Casagrande; E S Lachmann; V Druchkiv; D Bittersohl; M Spitzer; F Schüttauf Journal: Ophthalmologe Date: 2021-07-08 Impact factor: 1.059